| /* |
| * Generic process-grouping system. |
| * |
| * Based originally on the cpuset system, extracted by Paul Menage |
| * Copyright (C) 2006 Google, Inc |
| * |
| * Notifications support |
| * Copyright (C) 2009 Nokia Corporation |
| * Author: Kirill A. Shutemov |
| * |
| * Copyright notices from the original cpuset code: |
| * -------------------------------------------------- |
| * Copyright (C) 2003 BULL SA. |
| * Copyright (C) 2004-2006 Silicon Graphics, Inc. |
| * |
| * Portions derived from Patrick Mochel's sysfs code. |
| * sysfs is Copyright (c) 2001-3 Patrick Mochel |
| * |
| * 2003-10-10 Written by Simon Derr. |
| * 2003-10-22 Updates by Stephen Hemminger. |
| * 2004 May-July Rework by Paul Jackson. |
| * --------------------------------------------------- |
| * |
| * This file is subject to the terms and conditions of the GNU General Public |
| * License. See the file COPYING in the main directory of the Linux |
| * distribution for more details. |
| */ |
| |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| |
| #include <linux/cgroup.h> |
| #include <linux/cred.h> |
| #include <linux/ctype.h> |
| #include <linux/errno.h> |
| #include <linux/init_task.h> |
| #include <linux/kernel.h> |
| #include <linux/list.h> |
| #include <linux/magic.h> |
| #include <linux/mm.h> |
| #include <linux/mutex.h> |
| #include <linux/mount.h> |
| #include <linux/pagemap.h> |
| #include <linux/proc_fs.h> |
| #include <linux/rcupdate.h> |
| #include <linux/sched.h> |
| #include <linux/slab.h> |
| #include <linux/spinlock.h> |
| #include <linux/percpu-rwsem.h> |
| #include <linux/string.h> |
| #include <linux/sort.h> |
| #include <linux/kmod.h> |
| #include <linux/delayacct.h> |
| #include <linux/cgroupstats.h> |
| #include <linux/hashtable.h> |
| #include <linux/pid_namespace.h> |
| #include <linux/idr.h> |
| #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */ |
| #include <linux/kthread.h> |
| #include <linux/delay.h> |
| #include <linux/atomic.h> |
| #include <linux/cpuset.h> |
| #include <linux/proc_ns.h> |
| #include <linux/nsproxy.h> |
| #include <linux/file.h> |
| #include <net/sock.h> |
| |
| /* |
| * pidlists linger the following amount before being destroyed. The goal |
| * is avoiding frequent destruction in the middle of consecutive read calls |
| * Expiring in the middle is a performance problem not a correctness one. |
| * 1 sec should be enough. |
| */ |
| #define CGROUP_PIDLIST_DESTROY_DELAY HZ |
| |
| #define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \ |
| MAX_CFTYPE_NAME + 2) |
| |
| /* |
| * cgroup_mutex is the master lock. Any modification to cgroup or its |
| * hierarchy must be performed while holding it. |
| * |
| * css_set_lock protects task->cgroups pointer, the list of css_set |
| * objects, and the chain of tasks off each css_set. |
| * |
| * These locks are exported if CONFIG_PROVE_RCU so that accessors in |
| * cgroup.h can use them for lockdep annotations. |
| */ |
| #ifdef CONFIG_PROVE_RCU |
| DEFINE_MUTEX(cgroup_mutex); |
| DEFINE_SPINLOCK(css_set_lock); |
| EXPORT_SYMBOL_GPL(cgroup_mutex); |
| EXPORT_SYMBOL_GPL(css_set_lock); |
| #else |
| static DEFINE_MUTEX(cgroup_mutex); |
| static DEFINE_SPINLOCK(css_set_lock); |
| #endif |
| |
| /* |
| * Protects cgroup_idr and css_idr so that IDs can be released without |
| * grabbing cgroup_mutex. |
| */ |
| static DEFINE_SPINLOCK(cgroup_idr_lock); |
| |
| /* |
| * Protects cgroup_file->kn for !self csses. It synchronizes notifications |
| * against file removal/re-creation across css hiding. |
| */ |
| static DEFINE_SPINLOCK(cgroup_file_kn_lock); |
| |
| /* |
| * Protects cgroup_subsys->release_agent_path. Modifying it also requires |
| * cgroup_mutex. Reading requires either cgroup_mutex or this spinlock. |
| */ |
| static DEFINE_SPINLOCK(release_agent_path_lock); |
| |
| struct percpu_rw_semaphore cgroup_threadgroup_rwsem; |
| |
| #define cgroup_assert_mutex_or_rcu_locked() \ |
| RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ |
| !lockdep_is_held(&cgroup_mutex), \ |
| "cgroup_mutex or RCU read lock required"); |
| |
| /* |
| * cgroup destruction makes heavy use of work items and there can be a lot |
| * of concurrent destructions. Use a separate workqueue so that cgroup |
| * destruction work items don't end up filling up max_active of system_wq |
| * which may lead to deadlock. |
| */ |
| static struct workqueue_struct *cgroup_destroy_wq; |
| |
| /* |
| * pidlist destructions need to be flushed on cgroup destruction. Use a |
| * separate workqueue as flush domain. |
| */ |
| static struct workqueue_struct *cgroup_pidlist_destroy_wq; |
| |
| /* generate an array of cgroup subsystem pointers */ |
| #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys, |
| static struct cgroup_subsys *cgroup_subsys[] = { |
| #include <linux/cgroup_subsys.h> |
| }; |
| #undef SUBSYS |
| |
| /* array of cgroup subsystem names */ |
| #define SUBSYS(_x) [_x ## _cgrp_id] = #_x, |
| static const char *cgroup_subsys_name[] = { |
| #include <linux/cgroup_subsys.h> |
| }; |
| #undef SUBSYS |
| |
| /* array of static_keys for cgroup_subsys_enabled() and cgroup_subsys_on_dfl() */ |
| #define SUBSYS(_x) \ |
| DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key); \ |
| DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key); \ |
| EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key); \ |
| EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key); |
| #include <linux/cgroup_subsys.h> |
| #undef SUBSYS |
| |
| #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_enabled_key, |
| static struct static_key_true *cgroup_subsys_enabled_key[] = { |
| #include <linux/cgroup_subsys.h> |
| }; |
| #undef SUBSYS |
| |
| #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_on_dfl_key, |
| static struct static_key_true *cgroup_subsys_on_dfl_key[] = { |
| #include <linux/cgroup_subsys.h> |
| }; |
| #undef SUBSYS |
| |
| /* |
| * The default hierarchy, reserved for the subsystems that are otherwise |
| * unattached - it never has more than a single cgroup, and all tasks are |
| * part of that cgroup. |
| */ |
| struct cgroup_root cgrp_dfl_root; |
| EXPORT_SYMBOL_GPL(cgrp_dfl_root); |
| |
| /* |
| * The default hierarchy always exists but is hidden until mounted for the |
| * first time. This is for backward compatibility. |
| */ |
| static bool cgrp_dfl_visible; |
| |
| /* Controllers blocked by the commandline in v1 */ |
| static u16 cgroup_no_v1_mask; |
| |
| /* some controllers are not supported in the default hierarchy */ |
| static u16 cgrp_dfl_inhibit_ss_mask; |
| |
| /* some controllers are implicitly enabled on the default hierarchy */ |
| static unsigned long cgrp_dfl_implicit_ss_mask; |
| |
| /* The list of hierarchy roots */ |
| |
| static LIST_HEAD(cgroup_roots); |
| static int cgroup_root_count; |
| |
| /* hierarchy ID allocation and mapping, protected by cgroup_mutex */ |
| static DEFINE_IDR(cgroup_hierarchy_idr); |
| |
| /* |
| * Assign a monotonically increasing serial number to csses. It guarantees |
| * cgroups with bigger numbers are newer than those with smaller numbers. |
| * Also, as csses are always appended to the parent's ->children list, it |
| * guarantees that sibling csses are always sorted in the ascending serial |
| * number order on the list. Protected by cgroup_mutex. |
| */ |
| static u64 css_serial_nr_next = 1; |
| |
| /* |
| * These bitmask flags indicate whether tasks in the fork and exit paths have |
| * fork/exit handlers to call. This avoids us having to do extra work in the |
| * fork/exit path to check which subsystems have fork/exit callbacks. |
| */ |
| static u16 have_fork_callback __read_mostly; |
| static u16 have_exit_callback __read_mostly; |
| static u16 have_free_callback __read_mostly; |
| |
| /* cgroup namespace for init task */ |
| struct cgroup_namespace init_cgroup_ns = { |
| .count = { .counter = 2, }, |
| .user_ns = &init_user_ns, |
| .ns.ops = &cgroupns_operations, |
| .ns.inum = PROC_CGROUP_INIT_INO, |
| .root_cset = &init_css_set, |
| }; |
| |
| /* Ditto for the can_fork callback. */ |
| static u16 have_canfork_callback __read_mostly; |
| |
| static struct file_system_type cgroup2_fs_type; |
| static struct cftype cgroup_dfl_base_files[]; |
| static struct cftype cgroup_legacy_base_files[]; |
| |
| static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask); |
| static void cgroup_lock_and_drain_offline(struct cgroup *cgrp); |
| static int cgroup_apply_control(struct cgroup *cgrp); |
| static void cgroup_finalize_control(struct cgroup *cgrp, int ret); |
| static void css_task_iter_advance(struct css_task_iter *it); |
| static int cgroup_destroy_locked(struct cgroup *cgrp); |
| static struct cgroup_subsys_state *css_create(struct cgroup *cgrp, |
| struct cgroup_subsys *ss); |
| static void css_release(struct percpu_ref *ref); |
| static void kill_css(struct cgroup_subsys_state *css); |
| static int cgroup_addrm_files(struct cgroup_subsys_state *css, |
| struct cgroup *cgrp, struct cftype cfts[], |
| bool is_add); |
| |
| /** |
| * cgroup_ssid_enabled - cgroup subsys enabled test by subsys ID |
| * @ssid: subsys ID of interest |
| * |
| * cgroup_subsys_enabled() can only be used with literal subsys names which |
| * is fine for individual subsystems but unsuitable for cgroup core. This |
| * is slower static_key_enabled() based test indexed by @ssid. |
| */ |
| static bool cgroup_ssid_enabled(int ssid) |
| { |
| if (CGROUP_SUBSYS_COUNT == 0) |
| return false; |
| |
| return static_key_enabled(cgroup_subsys_enabled_key[ssid]); |
| } |
| |
| static bool cgroup_ssid_no_v1(int ssid) |
| { |
| return cgroup_no_v1_mask & (1 << ssid); |
| } |
| |
| /** |
| * cgroup_on_dfl - test whether a cgroup is on the default hierarchy |
| * @cgrp: the cgroup of interest |
| * |
| * The default hierarchy is the v2 interface of cgroup and this function |
| * can be used to test whether a cgroup is on the default hierarchy for |
| * cases where a subsystem should behave differnetly depending on the |
| * interface version. |
| * |
| * The set of behaviors which change on the default hierarchy are still |
| * being determined and the mount option is prefixed with __DEVEL__. |
| * |
| * List of changed behaviors: |
| * |
| * - Mount options "noprefix", "xattr", "clone_children", "release_agent" |
| * and "name" are disallowed. |
| * |
| * - When mounting an existing superblock, mount options should match. |
| * |
| * - Remount is disallowed. |
| * |
| * - rename(2) is disallowed. |
| * |
| * - "tasks" is removed. Everything should be at process granularity. Use |
| * "cgroup.procs" instead. |
| * |
| * - "cgroup.procs" is not sorted. pids will be unique unless they got |
| * recycled inbetween reads. |
| * |
| * - "release_agent" and "notify_on_release" are removed. Replacement |
| * notification mechanism will be implemented. |
| * |
| * - "cgroup.clone_children" is removed. |
| * |
| * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup |
| * and its descendants contain no task; otherwise, 1. The file also |
| * generates kernfs notification which can be monitored through poll and |
| * [di]notify when the value of the file changes. |
| * |
| * - cpuset: tasks will be kept in empty cpusets when hotplug happens and |
| * take masks of ancestors with non-empty cpus/mems, instead of being |
| * moved to an ancestor. |
| * |
| * - cpuset: a task can be moved into an empty cpuset, and again it takes |
| * masks of ancestors. |
| * |
| * - memcg: use_hierarchy is on by default and the cgroup file for the flag |
| * is not created. |
| * |
| * - blkcg: blk-throttle becomes properly hierarchical. |
| * |
| * - debug: disallowed on the default hierarchy. |
| */ |
| static bool cgroup_on_dfl(const struct cgroup *cgrp) |
| { |
| return cgrp->root == &cgrp_dfl_root; |
| } |
| |
| /* IDR wrappers which synchronize using cgroup_idr_lock */ |
| static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end, |
| gfp_t gfp_mask) |
| { |
| int ret; |
| |
| idr_preload(gfp_mask); |
| spin_lock_bh(&cgroup_idr_lock); |
| ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_DIRECT_RECLAIM); |
| spin_unlock_bh(&cgroup_idr_lock); |
| idr_preload_end(); |
| return ret; |
| } |
| |
| static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id) |
| { |
| void *ret; |
| |
| spin_lock_bh(&cgroup_idr_lock); |
| ret = idr_replace(idr, ptr, id); |
| spin_unlock_bh(&cgroup_idr_lock); |
| return ret; |
| } |
| |
| static void cgroup_idr_remove(struct idr *idr, int id) |
| { |
| spin_lock_bh(&cgroup_idr_lock); |
| idr_remove(idr, id); |
| spin_unlock_bh(&cgroup_idr_lock); |
| } |
| |
| static struct cgroup *cgroup_parent(struct cgroup *cgrp) |
| { |
| struct cgroup_subsys_state *parent_css = cgrp->self.parent; |
| |
| if (parent_css) |
| return container_of(parent_css, struct cgroup, self); |
| return NULL; |
| } |
| |
| /* subsystems visibly enabled on a cgroup */ |
| static u16 cgroup_control(struct cgroup *cgrp) |
| { |
| struct cgroup *parent = cgroup_parent(cgrp); |
| u16 root_ss_mask = cgrp->root->subsys_mask; |
| |
| if (parent) |
| return parent->subtree_control; |
| |
| if (cgroup_on_dfl(cgrp)) |
| root_ss_mask &= ~(cgrp_dfl_inhibit_ss_mask | |
| cgrp_dfl_implicit_ss_mask); |
| return root_ss_mask; |
| } |
| |
| /* subsystems enabled on a cgroup */ |
| static u16 cgroup_ss_mask(struct cgroup *cgrp) |
| { |
| struct cgroup *parent = cgroup_parent(cgrp); |
| |
| if (parent) |
| return parent->subtree_ss_mask; |
| |
| return cgrp->root->subsys_mask; |
| } |
| |
| /** |
| * cgroup_css - obtain a cgroup's css for the specified subsystem |
| * @cgrp: the cgroup of interest |
| * @ss: the subsystem of interest (%NULL returns @cgrp->self) |
| * |
| * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This |
| * function must be called either under cgroup_mutex or rcu_read_lock() and |
| * the caller is responsible for pinning the returned css if it wants to |
| * keep accessing it outside the said locks. This function may return |
| * %NULL if @cgrp doesn't have @subsys_id enabled. |
| */ |
| static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp, |
| struct cgroup_subsys *ss) |
| { |
| if (ss) |
| return rcu_dereference_check(cgrp->subsys[ss->id], |
| lockdep_is_held(&cgroup_mutex)); |
| else |
| return &cgrp->self; |
| } |
| |
| /** |
| * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem |
| * @cgrp: the cgroup of interest |
| * @ss: the subsystem of interest (%NULL returns @cgrp->self) |
| * |
| * Similar to cgroup_css() but returns the effective css, which is defined |
| * as the matching css of the nearest ancestor including self which has @ss |
| * enabled. If @ss is associated with the hierarchy @cgrp is on, this |
| * function is guaranteed to return non-NULL css. |
| */ |
| static struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp, |
| struct cgroup_subsys *ss) |
| { |
| lockdep_assert_held(&cgroup_mutex); |
| |
| if (!ss) |
| return &cgrp->self; |
| |
| /* |
| * This function is used while updating css associations and thus |
| * can't test the csses directly. Test ss_mask. |
| */ |
| while (!(cgroup_ss_mask(cgrp) & (1 << ss->id))) { |
| cgrp = cgroup_parent(cgrp); |
| if (!cgrp) |
| return NULL; |
| } |
| |
| return cgroup_css(cgrp, ss); |
| } |
| |
| /** |
| * cgroup_get_e_css - get a cgroup's effective css for the specified subsystem |
| * @cgrp: the cgroup of interest |
| * @ss: the subsystem of interest |
| * |
| * Find and get the effective css of @cgrp for @ss. The effective css is |
| * defined as the matching css of the nearest ancestor including self which |
| * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on, |
| * the root css is returned, so this function always returns a valid css. |
| * The returned css must be put using css_put(). |
| */ |
| struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp, |
| struct cgroup_subsys *ss) |
| { |
| struct cgroup_subsys_state *css; |
| |
| rcu_read_lock(); |
| |
| do { |
| css = cgroup_css(cgrp, ss); |
| |
| if (css && css_tryget_online(css)) |
| goto out_unlock; |
| cgrp = cgroup_parent(cgrp); |
| } while (cgrp); |
| |
| css = init_css_set.subsys[ss->id]; |
| css_get(css); |
| out_unlock: |
| rcu_read_unlock(); |
| return css; |
| } |
| |
| /* convenient tests for these bits */ |
| static inline bool cgroup_is_dead(const struct cgroup *cgrp) |
| { |
| return !(cgrp->self.flags & CSS_ONLINE); |
| } |
| |
| static void cgroup_get(struct cgroup *cgrp) |
| { |
| WARN_ON_ONCE(cgroup_is_dead(cgrp)); |
| css_get(&cgrp->self); |
| } |
| |
| static bool cgroup_tryget(struct cgroup *cgrp) |
| { |
| return css_tryget(&cgrp->self); |
| } |
| |
| struct cgroup_subsys_state *of_css(struct kernfs_open_file *of) |
| { |
| struct cgroup *cgrp = of->kn->parent->priv; |
| struct cftype *cft = of_cft(of); |
| |
| /* |
| * This is open and unprotected implementation of cgroup_css(). |
| * seq_css() is only called from a kernfs file operation which has |
| * an active reference on the file. Because all the subsystem |
| * files are drained before a css is disassociated with a cgroup, |
| * the matching css from the cgroup's subsys table is guaranteed to |
| * be and stay valid until the enclosing operation is complete. |
| */ |
| if (cft->ss) |
| return rcu_dereference_raw(cgrp->subsys[cft->ss->id]); |
| else |
| return &cgrp->self; |
| } |
| EXPORT_SYMBOL_GPL(of_css); |
| |
| static int notify_on_release(const struct cgroup *cgrp) |
| { |
| return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
| } |
| |
| /** |
| * for_each_css - iterate all css's of a cgroup |
| * @css: the iteration cursor |
| * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end |
| * @cgrp: the target cgroup to iterate css's of |
| * |
| * Should be called under cgroup_[tree_]mutex. |
| */ |
| #define for_each_css(css, ssid, cgrp) \ |
| for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ |
| if (!((css) = rcu_dereference_check( \ |
| (cgrp)->subsys[(ssid)], \ |
| lockdep_is_held(&cgroup_mutex)))) { } \ |
| else |
| |
| /** |
| * for_each_e_css - iterate all effective css's of a cgroup |
| * @css: the iteration cursor |
| * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end |
| * @cgrp: the target cgroup to iterate css's of |
| * |
| * Should be called under cgroup_[tree_]mutex. |
| */ |
| #define for_each_e_css(css, ssid, cgrp) \ |
| for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ |
| if (!((css) = cgroup_e_css(cgrp, cgroup_subsys[(ssid)]))) \ |
| ; \ |
| else |
| |
| /** |
| * for_each_subsys - iterate all enabled cgroup subsystems |
| * @ss: the iteration cursor |
| * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end |
| */ |
| #define for_each_subsys(ss, ssid) \ |
| for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \ |
| (((ss) = cgroup_subsys[ssid]) || true); (ssid)++) |
| |
| /** |
| * do_each_subsys_mask - filter for_each_subsys with a bitmask |
| * @ss: the iteration cursor |
| * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end |
| * @ss_mask: the bitmask |
| * |
| * The block will only run for cases where the ssid-th bit (1 << ssid) of |
| * @ss_mask is set. |
| */ |
| #define do_each_subsys_mask(ss, ssid, ss_mask) do { \ |
| unsigned long __ss_mask = (ss_mask); \ |
| if (!CGROUP_SUBSYS_COUNT) { /* to avoid spurious gcc warning */ \ |
| (ssid) = 0; \ |
| break; \ |
| } \ |
| for_each_set_bit(ssid, &__ss_mask, CGROUP_SUBSYS_COUNT) { \ |
| (ss) = cgroup_subsys[ssid]; \ |
| { |
| |
| #define while_each_subsys_mask() \ |
| } \ |
| } \ |
| } while (false) |
| |
| /* iterate across the hierarchies */ |
| #define for_each_root(root) \ |
| list_for_each_entry((root), &cgroup_roots, root_list) |
| |
| /* iterate over child cgrps, lock should be held throughout iteration */ |
| #define cgroup_for_each_live_child(child, cgrp) \ |
| list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \ |
| if (({ lockdep_assert_held(&cgroup_mutex); \ |
| cgroup_is_dead(child); })) \ |
| ; \ |
| else |
| |
| /* walk live descendants in preorder */ |
| #define cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) \ |
| css_for_each_descendant_pre((d_css), cgroup_css((cgrp), NULL)) \ |
| if (({ lockdep_assert_held(&cgroup_mutex); \ |
| (dsct) = (d_css)->cgroup; \ |
| cgroup_is_dead(dsct); })) \ |
| ; \ |
| else |
| |
| /* walk live descendants in postorder */ |
| #define cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) \ |
| css_for_each_descendant_post((d_css), cgroup_css((cgrp), NULL)) \ |
| if (({ lockdep_assert_held(&cgroup_mutex); \ |
| (dsct) = (d_css)->cgroup; \ |
| cgroup_is_dead(dsct); })) \ |
| ; \ |
| else |
| |
| static void cgroup_release_agent(struct work_struct *work); |
| static void check_for_release(struct cgroup *cgrp); |
| |
| /* |
| * A cgroup can be associated with multiple css_sets as different tasks may |
| * belong to different cgroups on different hierarchies. In the other |
| * direction, a css_set is naturally associated with multiple cgroups. |
| * This M:N relationship is represented by the following link structure |
| * which exists for each association and allows traversing the associations |
| * from both sides. |
| */ |
| struct cgrp_cset_link { |
| /* the cgroup and css_set this link associates */ |
| struct cgroup *cgrp; |
| struct css_set *cset; |
| |
| /* list of cgrp_cset_links anchored at cgrp->cset_links */ |
| struct list_head cset_link; |
| |
| /* list of cgrp_cset_links anchored at css_set->cgrp_links */ |
| struct list_head cgrp_link; |
| }; |
| |
| /* |
| * The default css_set - used by init and its children prior to any |
| * hierarchies being mounted. It contains a pointer to the root state |
| * for each subsystem. Also used to anchor the list of css_sets. Not |
| * reference-counted, to improve performance when child cgroups |
| * haven't been created. |
| */ |
| struct css_set init_css_set = { |
| .refcount = ATOMIC_INIT(1), |
| .cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links), |
| .tasks = LIST_HEAD_INIT(init_css_set.tasks), |
| .mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks), |
| .mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node), |
| .mg_node = LIST_HEAD_INIT(init_css_set.mg_node), |
| .task_iters = LIST_HEAD_INIT(init_css_set.task_iters), |
| }; |
| |
| static int css_set_count = 1; /* 1 for init_css_set */ |
| |
| /** |
| * css_set_populated - does a css_set contain any tasks? |
| * @cset: target css_set |
| */ |
| static bool css_set_populated(struct css_set *cset) |
| { |
| lockdep_assert_held(&css_set_lock); |
| |
| return !list_empty(&cset->tasks) || !list_empty(&cset->mg_tasks); |
| } |
| |
| /** |
| * cgroup_update_populated - updated populated count of a cgroup |
| * @cgrp: the target cgroup |
| * @populated: inc or dec populated count |
| * |
| * One of the css_sets associated with @cgrp is either getting its first |
| * task or losing the last. Update @cgrp->populated_cnt accordingly. The |
| * count is propagated towards root so that a given cgroup's populated_cnt |
| * is zero iff the cgroup and all its descendants don't contain any tasks. |
| * |
| * @cgrp's interface file "cgroup.populated" is zero if |
| * @cgrp->populated_cnt is zero and 1 otherwise. When @cgrp->populated_cnt |
| * changes from or to zero, userland is notified that the content of the |
| * interface file has changed. This can be used to detect when @cgrp and |
| * its descendants become populated or empty. |
| */ |
| static void cgroup_update_populated(struct cgroup *cgrp, bool populated) |
| { |
| lockdep_assert_held(&css_set_lock); |
| |
| do { |
| bool trigger; |
| |
| if (populated) |
| trigger = !cgrp->populated_cnt++; |
| else |
| trigger = !--cgrp->populated_cnt; |
| |
| if (!trigger) |
| break; |
| |
| check_for_release(cgrp); |
| cgroup_file_notify(&cgrp->events_file); |
| |
| cgrp = cgroup_parent(cgrp); |
| } while (cgrp); |
| } |
| |
| /** |
| * css_set_update_populated - update populated state of a css_set |
| * @cset: target css_set |
| * @populated: whether @cset is populated or depopulated |
| * |
| * @cset is either getting the first task or losing the last. Update the |
| * ->populated_cnt of all associated cgroups accordingly. |
| */ |
| static void css_set_update_populated(struct css_set *cset, bool populated) |
| { |
| struct cgrp_cset_link *link; |
| |
| lockdep_assert_held(&css_set_lock); |
| |
| list_for_each_entry(link, &cset->cgrp_links, cgrp_link) |
| cgroup_update_populated(link->cgrp, populated); |
| } |
| |
| /** |
| * css_set_move_task - move a task from one css_set to another |
| * @task: task being moved |
| * @from_cset: css_set @task currently belongs to (may be NULL) |
| * @to_cset: new css_set @task is being moved to (may be NULL) |
| * @use_mg_tasks: move to @to_cset->mg_tasks instead of ->tasks |
| * |
| * Move @task from @from_cset to @to_cset. If @task didn't belong to any |
| * css_set, @from_cset can be NULL. If @task is being disassociated |
| * instead of moved, @to_cset can be NULL. |
| * |
| * This function automatically handles populated_cnt updates and |
| * css_task_iter adjustments but the caller is responsible for managing |
| * @from_cset and @to_cset's reference counts. |
| */ |
| static void css_set_move_task(struct task_struct *task, |
| struct css_set *from_cset, struct css_set *to_cset, |
| bool use_mg_tasks) |
| { |
| lockdep_assert_held(&css_set_lock); |
| |
| if (to_cset && !css_set_populated(to_cset)) |
| css_set_update_populated(to_cset, true); |
| |
| if (from_cset) { |
| struct css_task_iter *it, *pos; |
| |
| WARN_ON_ONCE(list_empty(&task->cg_list)); |
| |
| /* |
| * @task is leaving, advance task iterators which are |
| * pointing to it so that they can resume at the next |
| * position. Advancing an iterator might remove it from |
| * the list, use safe walk. See css_task_iter_advance*() |
| * for details. |
| */ |
| list_for_each_entry_safe(it, pos, &from_cset->task_iters, |
| iters_node) |
| if (it->task_pos == &task->cg_list) |
| css_task_iter_advance(it); |
| |
| list_del_init(&task->cg_list); |
| if (!css_set_populated(from_cset)) |
| css_set_update_populated(from_cset, false); |
| } else { |
| WARN_ON_ONCE(!list_empty(&task->cg_list)); |
| } |
| |
| if (to_cset) { |
| /* |
| * We are synchronized through cgroup_threadgroup_rwsem |
| * against PF_EXITING setting such that we can't race |
| * against cgroup_exit() changing the css_set to |
| * init_css_set and dropping the old one. |
| */ |
| WARN_ON_ONCE(task->flags & PF_EXITING); |
| |
| rcu_assign_pointer(task->cgroups, to_cset); |
| list_add_tail(&task->cg_list, use_mg_tasks ? &to_cset->mg_tasks : |
| &to_cset->tasks); |
| } |
| } |
| |
| /* |
| * hash table for cgroup groups. This improves the performance to find |
| * an existing css_set. This hash doesn't (currently) take into |
| * account cgroups in empty hierarchies. |
| */ |
| #define CSS_SET_HASH_BITS 7 |
| static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS); |
| |
| static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) |
| { |
| unsigned long key = 0UL; |
| struct cgroup_subsys *ss; |
| int i; |
| |
| for_each_subsys(ss, i) |
| key += (unsigned long)css[i]; |
| key = (key >> 16) ^ key; |
| |
| return key; |
| } |
| |
| static void put_css_set_locked(struct css_set *cset) |
| { |
| struct cgrp_cset_link *link, *tmp_link; |
| struct cgroup_subsys *ss; |
| int ssid; |
| |
| lockdep_assert_held(&css_set_lock); |
| |
| if (!atomic_dec_and_test(&cset->refcount)) |
| return; |
| |
| /* This css_set is dead. unlink it and release cgroup and css refs */ |
| for_each_subsys(ss, ssid) { |
| list_del(&cset->e_cset_node[ssid]); |
| css_put(cset->subsys[ssid]); |
| } |
| hash_del(&cset->hlist); |
| css_set_count--; |
| |
| list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) { |
| list_del(&link->cset_link); |
| list_del(&link->cgrp_link); |
| if (cgroup_parent(link->cgrp)) |
| cgroup_put(link->cgrp); |
| kfree(link); |
| } |
| |
| kfree_rcu(cset, rcu_head); |
| } |
| |
| static void put_css_set(struct css_set *cset) |
| { |
| unsigned long flags; |
| |
| /* |
| * Ensure that the refcount doesn't hit zero while any readers |
| * can see it. Similar to atomic_dec_and_lock(), but for an |
| * rwlock |
| */ |
| if (atomic_add_unless(&cset->refcount, -1, 1)) |
| return; |
| |
| spin_lock_irqsave(&css_set_lock, flags); |
| put_css_set_locked(cset); |
| spin_unlock_irqrestore(&css_set_lock, flags); |
| } |
| |
| /* |
| * refcounted get/put for css_set objects |
| */ |
| static inline void get_css_set(struct css_set *cset) |
| { |
| atomic_inc(&cset->refcount); |
| } |
| |
| /** |
| * compare_css_sets - helper function for find_existing_css_set(). |
| * @cset: candidate css_set being tested |
| * @old_cset: existing css_set for a task |
| * @new_cgrp: cgroup that's being entered by the task |
| * @template: desired set of css pointers in css_set (pre-calculated) |
| * |
| * Returns true if "cset" matches "old_cset" except for the hierarchy |
| * which "new_cgrp" belongs to, for which it should match "new_cgrp". |
| */ |
| static bool compare_css_sets(struct css_set *cset, |
| struct css_set *old_cset, |
| struct cgroup *new_cgrp, |
| struct cgroup_subsys_state *template[]) |
| { |
| struct list_head *l1, *l2; |
| |
| /* |
| * On the default hierarchy, there can be csets which are |
| * associated with the same set of cgroups but different csses. |
| * Let's first ensure that csses match. |
| */ |
| if (memcmp(template, cset->subsys, sizeof(cset->subsys))) |
| return false; |
| |
| /* |
| * Compare cgroup pointers in order to distinguish between |
| * different cgroups in hierarchies. As different cgroups may |
| * share the same effective css, this comparison is always |
| * necessary. |
| */ |
| l1 = &cset->cgrp_links; |
| l2 = &old_cset->cgrp_links; |
| while (1) { |
| struct cgrp_cset_link *link1, *link2; |
| struct cgroup *cgrp1, *cgrp2; |
| |
| l1 = l1->next; |
| l2 = l2->next; |
| /* See if we reached the end - both lists are equal length. */ |
| if (l1 == &cset->cgrp_links) { |
| BUG_ON(l2 != &old_cset->cgrp_links); |
| break; |
| } else { |
| BUG_ON(l2 == &old_cset->cgrp_links); |
| } |
| /* Locate the cgroups associated with these links. */ |
| link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link); |
| link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link); |
| cgrp1 = link1->cgrp; |
| cgrp2 = link2->cgrp; |
| /* Hierarchies should be linked in the same order. */ |
| BUG_ON(cgrp1->root != cgrp2->root); |
| |
| /* |
| * If this hierarchy is the hierarchy of the cgroup |
| * that's changing, then we need to check that this |
| * css_set points to the new cgroup; if it's any other |
| * hierarchy, then this css_set should point to the |
| * same cgroup as the old css_set. |
| */ |
| if (cgrp1->root == new_cgrp->root) { |
| if (cgrp1 != new_cgrp) |
| return false; |
| } else { |
| if (cgrp1 != cgrp2) |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| /** |
| * find_existing_css_set - init css array and find the matching css_set |
| * @old_cset: the css_set that we're using before the cgroup transition |
| * @cgrp: the cgroup that we're moving into |
| * @template: out param for the new set of csses, should be clear on entry |
| */ |
| static struct css_set *find_existing_css_set(struct css_set *old_cset, |
| struct cgroup *cgrp, |
| struct cgroup_subsys_state *template[]) |
| { |
| struct cgroup_root *root = cgrp->root; |
| struct cgroup_subsys *ss; |
| struct css_set *cset; |
| unsigned long key; |
| int i; |
| |
| /* |
| * Build the set of subsystem state objects that we want to see in the |
| * new css_set. while subsystems can change globally, the entries here |
| * won't change, so no need for locking. |
| */ |
| for_each_subsys(ss, i) { |
| if (root->subsys_mask & (1UL << i)) { |
| /* |
| * @ss is in this hierarchy, so we want the |
| * effective css from @cgrp. |
| */ |
| template[i] = cgroup_e_css(cgrp, ss); |
| } else { |
| /* |
| * @ss is not in this hierarchy, so we don't want |
| * to change the css. |
| */ |
| template[i] = old_cset->subsys[i]; |
| } |
| } |
| |
| key = css_set_hash(template); |
| hash_for_each_possible(css_set_table, cset, hlist, key) { |
| if (!compare_css_sets(cset, old_cset, cgrp, template)) |
| continue; |
| |
| /* This css_set matches what we need */ |
| return cset; |
| } |
| |
| /* No existing cgroup group matched */ |
| return NULL; |
| } |
| |
| static void free_cgrp_cset_links(struct list_head *links_to_free) |
| { |
| struct cgrp_cset_link *link, *tmp_link; |
| |
| list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) { |
| list_del(&link->cset_link); |
| kfree(link); |
| } |
| } |
| |
| /** |
| * allocate_cgrp_cset_links - allocate cgrp_cset_links |
| * @count: the number of links to allocate |
| * @tmp_links: list_head the allocated links are put on |
| * |
| * Allocate @count cgrp_cset_link structures and chain them on @tmp_links |
| * through ->cset_link. Returns 0 on success or -errno. |
| */ |
| static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links) |
| { |
| struct cgrp_cset_link *link; |
| int i; |
| |
| INIT_LIST_HEAD(tmp_links); |
| |
| for (i = 0; i < count; i++) { |
| link = kzalloc(sizeof(*link), GFP_KERNEL); |
| if (!link) { |
| free_cgrp_cset_links(tmp_links); |
| return -ENOMEM; |
| } |
| list_add(&link->cset_link, tmp_links); |
| } |
| return 0; |
| } |
| |
| /** |
| * link_css_set - a helper function to link a css_set to a cgroup |
| * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links() |
| * @cset: the css_set to be linked |
| * @cgrp: the destination cgroup |
| */ |
| static void link_css_set(struct list_head *tmp_links, struct css_set *cset, |
| struct cgroup *cgrp) |
| { |
| struct cgrp_cset_link *link; |
| |
| BUG_ON(list_empty(tmp_links)); |
| |
| if (cgroup_on_dfl(cgrp)) |
| cset->dfl_cgrp = cgrp; |
| |
| link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link); |
| link->cset = cset; |
| link->cgrp = cgrp; |
| |
| /* |
| * Always add links to the tail of the lists so that the lists are |
| * in choronological order. |
| */ |
| list_move_tail(&link->cset_link, &cgrp->cset_links); |
| list_add_tail(&link->cgrp_link, &cset->cgrp_links); |
| |
| if (cgroup_parent(cgrp)) |
| cgroup_get(cgrp); |
| } |
| |
| /** |
| * find_css_set - return a new css_set with one cgroup updated |
| * @old_cset: the baseline css_set |
| * @cgrp: the cgroup to be updated |
| * |
| * Return a new css_set that's equivalent to @old_cset, but with @cgrp |
| * substituted into the appropriate hierarchy. |
| */ |
| static struct css_set *find_css_set(struct css_set *old_cset, |
| struct cgroup *cgrp) |
| { |
| struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { }; |
| struct css_set *cset; |
| struct list_head tmp_links; |
| struct cgrp_cset_link *link; |
| struct cgroup_subsys *ss; |
| unsigned long key; |
| int ssid; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| /* First see if we already have a cgroup group that matches |
| * the desired set */ |
| spin_lock_irq(&css_set_lock); |
| cset = find_existing_css_set(old_cset, cgrp, template); |
| if (cset) |
| get_css_set(cset); |
| spin_unlock_irq(&css_set_lock); |
| |
| if (cset) |
| return cset; |
| |
| cset = kzalloc(sizeof(*cset), GFP_KERNEL); |
| if (!cset) |
| return NULL; |
| |
| /* Allocate all the cgrp_cset_link objects that we'll need */ |
| if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) { |
| kfree(cset); |
| return NULL; |
| } |
| |
| atomic_set(&cset->refcount, 1); |
| INIT_LIST_HEAD(&cset->cgrp_links); |
| INIT_LIST_HEAD(&cset->tasks); |
| INIT_LIST_HEAD(&cset->mg_tasks); |
| INIT_LIST_HEAD(&cset->mg_preload_node); |
| INIT_LIST_HEAD(&cset->mg_node); |
| INIT_LIST_HEAD(&cset->task_iters); |
| INIT_HLIST_NODE(&cset->hlist); |
| |
| /* Copy the set of subsystem state objects generated in |
| * find_existing_css_set() */ |
| memcpy(cset->subsys, template, sizeof(cset->subsys)); |
| |
| spin_lock_irq(&css_set_lock); |
| /* Add reference counts and links from the new css_set. */ |
| list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) { |
| struct cgroup *c = link->cgrp; |
| |
| if (c->root == cgrp->root) |
| c = cgrp; |
| link_css_set(&tmp_links, cset, c); |
| } |
| |
| BUG_ON(!list_empty(&tmp_links)); |
| |
| css_set_count++; |
| |
| /* Add @cset to the hash table */ |
| key = css_set_hash(cset->subsys); |
| hash_add(css_set_table, &cset->hlist, key); |
| |
| for_each_subsys(ss, ssid) { |
| struct cgroup_subsys_state *css = cset->subsys[ssid]; |
| |
| list_add_tail(&cset->e_cset_node[ssid], |
| &css->cgroup->e_csets[ssid]); |
| css_get(css); |
| } |
| |
| spin_unlock_irq(&css_set_lock); |
| |
| return cset; |
| } |
| |
| static struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root) |
| { |
| struct cgroup *root_cgrp = kf_root->kn->priv; |
| |
| return root_cgrp->root; |
| } |
| |
| static int cgroup_init_root_id(struct cgroup_root *root) |
| { |
| int id; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 0, 0, GFP_KERNEL); |
| if (id < 0) |
| return id; |
| |
| root->hierarchy_id = id; |
| return 0; |
| } |
| |
| static void cgroup_exit_root_id(struct cgroup_root *root) |
| { |
| lockdep_assert_held(&cgroup_mutex); |
| |
| idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id); |
| } |
| |
| static void cgroup_free_root(struct cgroup_root *root) |
| { |
| if (root) { |
| idr_destroy(&root->cgroup_idr); |
| kfree(root); |
| } |
| } |
| |
| static void cgroup_destroy_root(struct cgroup_root *root) |
| { |
| struct cgroup *cgrp = &root->cgrp; |
| struct cgrp_cset_link *link, *tmp_link; |
| |
| cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp); |
| |
| BUG_ON(atomic_read(&root->nr_cgrps)); |
| BUG_ON(!list_empty(&cgrp->self.children)); |
| |
| /* Rebind all subsystems back to the default hierarchy */ |
| WARN_ON(rebind_subsystems(&cgrp_dfl_root, root->subsys_mask)); |
| |
| /* |
| * Release all the links from cset_links to this hierarchy's |
| * root cgroup |
| */ |
| spin_lock_irq(&css_set_lock); |
| |
| list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) { |
| list_del(&link->cset_link); |
| list_del(&link->cgrp_link); |
| kfree(link); |
| } |
| |
| spin_unlock_irq(&css_set_lock); |
| |
| if (!list_empty(&root->root_list)) { |
| list_del(&root->root_list); |
| cgroup_root_count--; |
| } |
| |
| cgroup_exit_root_id(root); |
| |
| mutex_unlock(&cgroup_mutex); |
| |
| kernfs_destroy_root(root->kf_root); |
| cgroup_free_root(root); |
| } |
| |
| /* |
| * look up cgroup associated with current task's cgroup namespace on the |
| * specified hierarchy |
| */ |
| static struct cgroup * |
| current_cgns_cgroup_from_root(struct cgroup_root *root) |
| { |
| struct cgroup *res = NULL; |
| struct css_set *cset; |
| |
| lockdep_assert_held(&css_set_lock); |
| |
| rcu_read_lock(); |
| |
| cset = current->nsproxy->cgroup_ns->root_cset; |
| if (cset == &init_css_set) { |
| res = &root->cgrp; |
| } else { |
| struct cgrp_cset_link *link; |
| |
| list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { |
| struct cgroup *c = link->cgrp; |
| |
| if (c->root == root) { |
| res = c; |
| break; |
| } |
| } |
| } |
| rcu_read_unlock(); |
| |
| BUG_ON(!res); |
| return res; |
| } |
| |
| /* look up cgroup associated with given css_set on the specified hierarchy */ |
| static struct cgroup *cset_cgroup_from_root(struct css_set *cset, |
| struct cgroup_root *root) |
| { |
| struct cgroup *res = NULL; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| lockdep_assert_held(&css_set_lock); |
| |
| if (cset == &init_css_set) { |
| res = &root->cgrp; |
| } else { |
| struct cgrp_cset_link *link; |
| |
| list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { |
| struct cgroup *c = link->cgrp; |
| |
| if (c->root == root) { |
| res = c; |
| break; |
| } |
| } |
| } |
| |
| BUG_ON(!res); |
| return res; |
| } |
| |
| /* |
| * Return the cgroup for "task" from the given hierarchy. Must be |
| * called with cgroup_mutex and css_set_lock held. |
| */ |
| static struct cgroup *task_cgroup_from_root(struct task_struct *task, |
| struct cgroup_root *root) |
| { |
| /* |
| * No need to lock the task - since we hold cgroup_mutex the |
| * task can't change groups, so the only thing that can happen |
| * is that it exits and its css is set back to init_css_set. |
| */ |
| return cset_cgroup_from_root(task_css_set(task), root); |
| } |
| |
| /* |
| * A task must hold cgroup_mutex to modify cgroups. |
| * |
| * Any task can increment and decrement the count field without lock. |
| * So in general, code holding cgroup_mutex can't rely on the count |
| * field not changing. However, if the count goes to zero, then only |
| * cgroup_attach_task() can increment it again. Because a count of zero |
| * means that no tasks are currently attached, therefore there is no |
| * way a task attached to that cgroup can fork (the other way to |
| * increment the count). So code holding cgroup_mutex can safely |
| * assume that if the count is zero, it will stay zero. Similarly, if |
| * a task holds cgroup_mutex on a cgroup with zero count, it |
| * knows that the cgroup won't be removed, as cgroup_rmdir() |
| * needs that mutex. |
| * |
| * A cgroup can only be deleted if both its 'count' of using tasks |
| * is zero, and its list of 'children' cgroups is empty. Since all |
| * tasks in the system use _some_ cgroup, and since there is always at |
| * least one task in the system (init, pid == 1), therefore, root cgroup |
| * always has either children cgroups and/or using tasks. So we don't |
| * need a special hack to ensure that root cgroup cannot be deleted. |
| * |
| * P.S. One more locking exception. RCU is used to guard the |
| * update of a tasks cgroup pointer by cgroup_attach_task() |
| */ |
| |
| static struct kernfs_syscall_ops cgroup_kf_syscall_ops; |
| static const struct file_operations proc_cgroupstats_operations; |
| |
| static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft, |
| char *buf) |
| { |
| struct cgroup_subsys *ss = cft->ss; |
| |
| if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) && |
| !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) |
| snprintf(buf, CGROUP_FILE_NAME_MAX, "%s.%s", |
| cgroup_on_dfl(cgrp) ? ss->name : ss->legacy_name, |
| cft->name); |
| else |
| strncpy(buf, cft->name, CGROUP_FILE_NAME_MAX); |
| return buf; |
| } |
| |
| /** |
| * cgroup_file_mode - deduce file mode of a control file |
| * @cft: the control file in question |
| * |
| * S_IRUGO for read, S_IWUSR for write. |
| */ |
| static umode_t cgroup_file_mode(const struct cftype *cft) |
| { |
| umode_t mode = 0; |
| |
| if (cft->read_u64 || cft->read_s64 || cft->seq_show) |
| mode |= S_IRUGO; |
| |
| if (cft->write_u64 || cft->write_s64 || cft->write) { |
| if (cft->flags & CFTYPE_WORLD_WRITABLE) |
| mode |= S_IWUGO; |
| else |
| mode |= S_IWUSR; |
| } |
| |
| return mode; |
| } |
| |
| /** |
| * cgroup_calc_subtree_ss_mask - calculate subtree_ss_mask |
| * @subtree_control: the new subtree_control mask to consider |
| * @this_ss_mask: available subsystems |
| * |
| * On the default hierarchy, a subsystem may request other subsystems to be |
| * enabled together through its ->depends_on mask. In such cases, more |
| * subsystems than specified in "cgroup.subtree_control" may be enabled. |
| * |
| * This function calculates which subsystems need to be enabled if |
| * @subtree_control is to be applied while restricted to @this_ss_mask. |
| */ |
| static u16 cgroup_calc_subtree_ss_mask(u16 subtree_control, u16 this_ss_mask) |
| { |
| u16 cur_ss_mask = subtree_control; |
| struct cgroup_subsys *ss; |
| int ssid; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| cur_ss_mask |= cgrp_dfl_implicit_ss_mask; |
| |
| while (true) { |
| u16 new_ss_mask = cur_ss_mask; |
| |
| do_each_subsys_mask(ss, ssid, cur_ss_mask) { |
| new_ss_mask |= ss->depends_on; |
| } while_each_subsys_mask(); |
| |
| /* |
| * Mask out subsystems which aren't available. This can |
| * happen only if some depended-upon subsystems were bound |
| * to non-default hierarchies. |
| */ |
| new_ss_mask &= this_ss_mask; |
| |
| if (new_ss_mask == cur_ss_mask) |
| break; |
| cur_ss_mask = new_ss_mask; |
| } |
| |
| return cur_ss_mask; |
| } |
| |
| /** |
| * cgroup_kn_unlock - unlocking helper for cgroup kernfs methods |
| * @kn: the kernfs_node being serviced |
| * |
| * This helper undoes cgroup_kn_lock_live() and should be invoked before |
| * the method finishes if locking succeeded. Note that once this function |
| * returns the cgroup returned by cgroup_kn_lock_live() may become |
| * inaccessible any time. If the caller intends to continue to access the |
| * cgroup, it should pin it before invoking this function. |
| */ |
| static void cgroup_kn_unlock(struct kernfs_node *kn) |
| { |
| struct cgroup *cgrp; |
| |
| if (kernfs_type(kn) == KERNFS_DIR) |
| cgrp = kn->priv; |
| else |
| cgrp = kn->parent->priv; |
| |
| mutex_unlock(&cgroup_mutex); |
| |
| kernfs_unbreak_active_protection(kn); |
| cgroup_put(cgrp); |
| } |
| |
| /** |
| * cgroup_kn_lock_live - locking helper for cgroup kernfs methods |
| * @kn: the kernfs_node being serviced |
| * @drain_offline: perform offline draining on the cgroup |
| * |
| * This helper is to be used by a cgroup kernfs method currently servicing |
| * @kn. It breaks the active protection, performs cgroup locking and |
| * verifies that the associated cgroup is alive. Returns the cgroup if |
| * alive; otherwise, %NULL. A successful return should be undone by a |
| * matching cgroup_kn_unlock() invocation. If @drain_offline is %true, the |
| * cgroup is drained of offlining csses before return. |
| * |
| * Any cgroup kernfs method implementation which requires locking the |
| * associated cgroup should use this helper. It avoids nesting cgroup |
| * locking under kernfs active protection and allows all kernfs operations |
| * including self-removal. |
| */ |
| static struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, |
| bool drain_offline) |
| { |
| struct cgroup *cgrp; |
| |
| if (kernfs_type(kn) == KERNFS_DIR) |
| cgrp = kn->priv; |
| else |
| cgrp = kn->parent->priv; |
| |
| /* |
| * We're gonna grab cgroup_mutex which nests outside kernfs |
| * active_ref. cgroup liveliness check alone provides enough |
| * protection against removal. Ensure @cgrp stays accessible and |
| * break the active_ref protection. |
| */ |
| if (!cgroup_tryget(cgrp)) |
| return NULL; |
| kernfs_break_active_protection(kn); |
| |
| if (drain_offline) |
| cgroup_lock_and_drain_offline(cgrp); |
| else |
| mutex_lock(&cgroup_mutex); |
| |
| if (!cgroup_is_dead(cgrp)) |
| return cgrp; |
| |
| cgroup_kn_unlock(kn); |
| return NULL; |
| } |
| |
| static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) |
| { |
| char name[CGROUP_FILE_NAME_MAX]; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| if (cft->file_offset) { |
| struct cgroup_subsys_state *css = cgroup_css(cgrp, cft->ss); |
| struct cgroup_file *cfile = (void *)css + cft->file_offset; |
| |
| spin_lock_irq(&cgroup_file_kn_lock); |
| cfile->kn = NULL; |
| spin_unlock_irq(&cgroup_file_kn_lock); |
| } |
| |
| kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name)); |
| } |
| |
| /** |
| * css_clear_dir - remove subsys files in a cgroup directory |
| * @css: taget css |
| */ |
| static void css_clear_dir(struct cgroup_subsys_state *css) |
| { |
| struct cgroup *cgrp = css->cgroup; |
| struct cftype *cfts; |
| |
| if (!(css->flags & CSS_VISIBLE)) |
| return; |
| |
| css->flags &= ~CSS_VISIBLE; |
| |
| list_for_each_entry(cfts, &css->ss->cfts, node) |
| cgroup_addrm_files(css, cgrp, cfts, false); |
| } |
| |
| /** |
| * css_populate_dir - create subsys files in a cgroup directory |
| * @css: target css |
| * |
| * On failure, no file is added. |
| */ |
| static int css_populate_dir(struct cgroup_subsys_state *css) |
| { |
| struct cgroup *cgrp = css->cgroup; |
| struct cftype *cfts, *failed_cfts; |
| int ret; |
| |
| if ((css->flags & CSS_VISIBLE) || !cgrp->kn) |
| return 0; |
| |
| if (!css->ss) { |
| if (cgroup_on_dfl(cgrp)) |
| cfts = cgroup_dfl_base_files; |
| else |
| cfts = cgroup_legacy_base_files; |
| |
| return cgroup_addrm_files(&cgrp->self, cgrp, cfts, true); |
| } |
| |
| list_for_each_entry(cfts, &css->ss->cfts, node) { |
| ret = cgroup_addrm_files(css, cgrp, cfts, true); |
| if (ret < 0) { |
| failed_cfts = cfts; |
| goto err; |
| } |
| } |
| |
| css->flags |= CSS_VISIBLE; |
| |
| return 0; |
| err: |
| list_for_each_entry(cfts, &css->ss->cfts, node) { |
| if (cfts == failed_cfts) |
| break; |
| cgroup_addrm_files(css, cgrp, cfts, false); |
| } |
| return ret; |
| } |
| |
| static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask) |
| { |
| struct cgroup *dcgrp = &dst_root->cgrp; |
| struct cgroup_subsys *ss; |
| int ssid, i, ret; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| do_each_subsys_mask(ss, ssid, ss_mask) { |
| /* |
| * If @ss has non-root csses attached to it, can't move. |
| * If @ss is an implicit controller, it is exempt from this |
| * rule and can be stolen. |
| */ |
| if (css_next_child(NULL, cgroup_css(&ss->root->cgrp, ss)) && |
| !ss->implicit_on_dfl) |
| return -EBUSY; |
| |
| /* can't move between two non-dummy roots either */ |
| if (ss->root != &cgrp_dfl_root && dst_root != &cgrp_dfl_root) |
| return -EBUSY; |
| } while_each_subsys_mask(); |
| |
| do_each_subsys_mask(ss, ssid, ss_mask) { |
| struct cgroup_root *src_root = ss->root; |
| struct cgroup *scgrp = &src_root->cgrp; |
| struct cgroup_subsys_state *css = cgroup_css(scgrp, ss); |
| struct css_set *cset; |
| |
| WARN_ON(!css || cgroup_css(dcgrp, ss)); |
| |
| /* disable from the source */ |
| src_root->subsys_mask &= ~(1 << ssid); |
| WARN_ON(cgroup_apply_control(scgrp)); |
| cgroup_finalize_control(scgrp, 0); |
| |
| /* rebind */ |
| RCU_INIT_POINTER(scgrp->subsys[ssid], NULL); |
| rcu_assign_pointer(dcgrp->subsys[ssid], css); |
| ss->root = dst_root; |
| css->cgroup = dcgrp; |
| |
| spin_lock_irq(&css_set_lock); |
| hash_for_each(css_set_table, i, cset, hlist) |
| list_move_tail(&cset->e_cset_node[ss->id], |
| &dcgrp->e_csets[ss->id]); |
| spin_unlock_irq(&css_set_lock); |
| |
| /* default hierarchy doesn't enable controllers by default */ |
| dst_root->subsys_mask |= 1 << ssid; |
| if (dst_root == &cgrp_dfl_root) { |
| static_branch_enable(cgroup_subsys_on_dfl_key[ssid]); |
| } else { |
| dcgrp->subtree_control |= 1 << ssid; |
| static_branch_disable(cgroup_subsys_on_dfl_key[ssid]); |
| } |
| |
| ret = cgroup_apply_control(dcgrp); |
| if (ret) |
| pr_warn("partial failure to rebind %s controller (err=%d)\n", |
| ss->name, ret); |
| |
| if (ss->bind) |
| ss->bind(css); |
| } while_each_subsys_mask(); |
| |
| kernfs_activate(dcgrp->kn); |
| return 0; |
| } |
| |
| static int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node, |
| struct kernfs_root *kf_root) |
| { |
| int len = 0; |
| char *buf = NULL; |
| struct cgroup_root *kf_cgroot = cgroup_root_from_kf(kf_root); |
| struct cgroup *ns_cgroup; |
| |
| buf = kmalloc(PATH_MAX, GFP_KERNEL); |
| if (!buf) |
| return -ENOMEM; |
| |
| spin_lock_irq(&css_set_lock); |
| ns_cgroup = current_cgns_cgroup_from_root(kf_cgroot); |
| len = kernfs_path_from_node(kf_node, ns_cgroup->kn, buf, PATH_MAX); |
| spin_unlock_irq(&css_set_lock); |
| |
| if (len >= PATH_MAX) |
| len = -ERANGE; |
| else if (len > 0) { |
| seq_escape(sf, buf, " \t\n\\"); |
| len = 0; |
| } |
| kfree(buf); |
| return len; |
| } |
| |
| static int cgroup_show_options(struct seq_file *seq, |
| struct kernfs_root *kf_root) |
| { |
| struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
| struct cgroup_subsys *ss; |
| int ssid; |
| |
| if (root != &cgrp_dfl_root) |
| for_each_subsys(ss, ssid) |
| if (root->subsys_mask & (1 << ssid)) |
| seq_show_option(seq, ss->legacy_name, NULL); |
| if (root->flags & CGRP_ROOT_NOPREFIX) |
| seq_puts(seq, ",noprefix"); |
| if (root->flags & CGRP_ROOT_XATTR) |
| seq_puts(seq, ",xattr"); |
| |
| spin_lock(&release_agent_path_lock); |
| if (strlen(root->release_agent_path)) |
| seq_show_option(seq, "release_agent", |
| root->release_agent_path); |
| spin_unlock(&release_agent_path_lock); |
| |
| if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags)) |
| seq_puts(seq, ",clone_children"); |
| if (strlen(root->name)) |
| seq_show_option(seq, "name", root->name); |
| return 0; |
| } |
| |
| struct cgroup_sb_opts { |
| u16 subsys_mask; |
| unsigned int flags; |
| char *release_agent; |
| bool cpuset_clone_children; |
| char *name; |
| /* User explicitly requested empty subsystem */ |
| bool none; |
| }; |
| |
| static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) |
| { |
| char *token, *o = data; |
| bool all_ss = false, one_ss = false; |
| u16 mask = U16_MAX; |
| struct cgroup_subsys *ss; |
| int nr_opts = 0; |
| int i; |
| |
| #ifdef CONFIG_CPUSETS |
| mask = ~((u16)1 << cpuset_cgrp_id); |
| #endif |
| |
| memset(opts, 0, sizeof(*opts)); |
| |
| while ((token = strsep(&o, ",")) != NULL) { |
| nr_opts++; |
| |
| if (!*token) |
| return -EINVAL; |
| if (!strcmp(token, "none")) { |
| /* Explicitly have no subsystems */ |
| opts->none = true; |
| continue; |
| } |
| if (!strcmp(token, "all")) { |
| /* Mutually exclusive option 'all' + subsystem name */ |
| if (one_ss) |
| return -EINVAL; |
| all_ss = true; |
| continue; |
| } |
| if (!strcmp(token, "noprefix")) { |
| opts->flags |= CGRP_ROOT_NOPREFIX; |
| continue; |
| } |
| if (!strcmp(token, "clone_children")) { |
| opts->cpuset_clone_children = true; |
| continue; |
| } |
| if (!strcmp(token, "xattr")) { |
| opts->flags |= CGRP_ROOT_XATTR; |
| continue; |
| } |
| if (!strncmp(token, "release_agent=", 14)) { |
| /* Specifying two release agents is forbidden */ |
| if (opts->release_agent) |
| return -EINVAL; |
| opts->release_agent = |
| kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL); |
| if (!opts->release_agent) |
| return -ENOMEM; |
| continue; |
| } |
| if (!strncmp(token, "name=", 5)) { |
| const char *name = token + 5; |
| /* Can't specify an empty name */ |
| if (!strlen(name)) |
| return -EINVAL; |
| /* Must match [\w.-]+ */ |
| for (i = 0; i < strlen(name); i++) { |
| char c = name[i]; |
| if (isalnum(c)) |
| continue; |
| if ((c == '.') || (c == '-') || (c == '_')) |
| continue; |
| return -EINVAL; |
| } |
| /* Specifying two names is forbidden */ |
| if (opts->name) |
| return -EINVAL; |
| opts->name = kstrndup(name, |
| MAX_CGROUP_ROOT_NAMELEN - 1, |
| GFP_KERNEL); |
| if (!opts->name) |
| return -ENOMEM; |
| |
| continue; |
| } |
| |
| for_each_subsys(ss, i) { |
| if (strcmp(token, ss->legacy_name)) |
| continue; |
| if (!cgroup_ssid_enabled(i)) |
| continue; |
| if (cgroup_ssid_no_v1(i)) |
| continue; |
| |
| /* Mutually exclusive option 'all' + subsystem name */ |
| if (all_ss) |
| return -EINVAL; |
| opts->subsys_mask |= (1 << i); |
| one_ss = true; |
| |
| break; |
| } |
| if (i == CGROUP_SUBSYS_COUNT) |
| return -ENOENT; |
| } |
| |
| /* |
| * If the 'all' option was specified select all the subsystems, |
| * otherwise if 'none', 'name=' and a subsystem name options were |
| * not specified, let's default to 'all' |
| */ |
| if (all_ss || (!one_ss && !opts->none && !opts->name)) |
| for_each_subsys(ss, i) |
| if (cgroup_ssid_enabled(i) && !cgroup_ssid_no_v1(i)) |
| opts->subsys_mask |= (1 << i); |
| |
| /* |
| * We either have to specify by name or by subsystems. (So all |
| * empty hierarchies must have a name). |
| */ |
| if (!opts->subsys_mask && !opts->name) |
| return -EINVAL; |
| |
| /* |
| * Option noprefix was introduced just for backward compatibility |
| * with the old cpuset, so we allow noprefix only if mounting just |
| * the cpuset subsystem. |
| */ |
| if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask)) |
| return -EINVAL; |
| |
| /* Can't specify "none" and some subsystems */ |
| if (opts->subsys_mask && opts->none) |
| return -EINVAL; |
| |
| return 0; |
| } |
| |
| static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data) |
| { |
| int ret = 0; |
| struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
| struct cgroup_sb_opts opts; |
| u16 added_mask, removed_mask; |
| |
| if (root == &cgrp_dfl_root) { |
| pr_err("remount is not allowed\n"); |
| return -EINVAL; |
| } |
| |
| cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp); |
| |
| /* See what subsystems are wanted */ |
| ret = parse_cgroupfs_options(data, &opts); |
| if (ret) |
| goto out_unlock; |
| |
| if (opts.subsys_mask != root->subsys_mask || opts.release_agent) |
| pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n", |
| task_tgid_nr(current), current->comm); |
| |
| added_mask = opts.subsys_mask & ~root->subsys_mask; |
| removed_mask = root->subsys_mask & ~opts.subsys_mask; |
| |
| /* Don't allow flags or name to change at remount */ |
| if ((opts.flags ^ root->flags) || |
| (opts.name && strcmp(opts.name, root->name))) { |
| pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n", |
| opts.flags, opts.name ?: "", root->flags, root->name); |
| ret = -EINVAL; |
| goto out_unlock; |
| } |
| |
| /* remounting is not allowed for populated hierarchies */ |
| if (!list_empty(&root->cgrp.self.children)) { |
| ret = -EBUSY; |
| goto out_unlock; |
| } |
| |
| ret = rebind_subsystems(root, added_mask); |
| if (ret) |
| goto out_unlock; |
| |
| WARN_ON(rebind_subsystems(&cgrp_dfl_root, removed_mask)); |
| |
| if (opts.release_agent) { |
| spin_lock(&release_agent_path_lock); |
| strcpy(root->release_agent_path, opts.release_agent); |
| spin_unlock(&release_agent_path_lock); |
| } |
| out_unlock: |
| kfree(opts.release_agent); |
| kfree(opts.name); |
| mutex_unlock(&cgroup_mutex); |
| return ret; |
| } |
| |
| /* |
| * To reduce the fork() overhead for systems that are not actually using |
| * their cgroups capability, we don't maintain the lists running through |
| * each css_set to its tasks until we see the list actually used - in other |
| * words after the first mount. |
| */ |
| static bool use_task_css_set_links __read_mostly; |
| |
| static void cgroup_enable_task_cg_lists(void) |
| { |
| struct task_struct *p, *g; |
| |
| spin_lock_irq(&css_set_lock); |
| |
| if (use_task_css_set_links) |
| goto out_unlock; |
| |
| use_task_css_set_links = true; |
| |
| /* |
| * We need tasklist_lock because RCU is not safe against |
| * while_each_thread(). Besides, a forking task that has passed |
| * cgroup_post_fork() without seeing use_task_css_set_links = 1 |
| * is not guaranteed to have its child immediately visible in the |
| * tasklist if we walk through it with RCU. |
| */ |
| read_lock(&tasklist_lock); |
| do_each_thread(g, p) { |
| WARN_ON_ONCE(!list_empty(&p->cg_list) || |
| task_css_set(p) != &init_css_set); |
| |
| /* |
| * We should check if the process is exiting, otherwise |
| * it will race with cgroup_exit() in that the list |
| * entry won't be deleted though the process has exited. |
| * Do it while holding siglock so that we don't end up |
| * racing against cgroup_exit(). |
| * |
| * Interrupts were already disabled while acquiring |
| * the css_set_lock, so we do not need to disable it |
| * again when acquiring the sighand->siglock here. |
| */ |
| spin_lock(&p->sighand->siglock); |
| if (!(p->flags & PF_EXITING)) { |
| struct css_set *cset = task_css_set(p); |
| |
| if (!css_set_populated(cset)) |
| css_set_update_populated(cset, true); |
| list_add_tail(&p->cg_list, &cset->tasks); |
| get_css_set(cset); |
| } |
| spin_unlock(&p->sighand->siglock); |
| } while_each_thread(g, p); |
| read_unlock(&tasklist_lock); |
| out_unlock: |
| spin_unlock_irq(&css_set_lock); |
| } |
| |
| static void init_cgroup_housekeeping(struct cgroup *cgrp) |
| { |
| struct cgroup_subsys *ss; |
| int ssid; |
| |
| INIT_LIST_HEAD(&cgrp->self.sibling); |
| INIT_LIST_HEAD(&cgrp->self.children); |
| INIT_LIST_HEAD(&cgrp->cset_links); |
| INIT_LIST_HEAD(&cgrp->pidlists); |
| mutex_init(&cgrp->pidlist_mutex); |
| cgrp->self.cgroup = cgrp; |
| cgrp->self.flags |= CSS_ONLINE; |
| |
| for_each_subsys(ss, ssid) |
| INIT_LIST_HEAD(&cgrp->e_csets[ssid]); |
| |
| init_waitqueue_head(&cgrp->offline_waitq); |
| INIT_WORK(&cgrp->release_agent_work, cgroup_release_agent); |
| } |
| |
| static void init_cgroup_root(struct cgroup_root *root, |
| struct cgroup_sb_opts *opts) |
| { |
| struct cgroup *cgrp = &root->cgrp; |
| |
| INIT_LIST_HEAD(&root->root_list); |
| atomic_set(&root->nr_cgrps, 1); |
| cgrp->root = root; |
| init_cgroup_housekeeping(cgrp); |
| idr_init(&root->cgroup_idr); |
| |
| root->flags = opts->flags; |
| if (opts->release_agent) |
| strcpy(root->release_agent_path, opts->release_agent); |
| if (opts->name) |
| strcpy(root->name, opts->name); |
| if (opts->cpuset_clone_children) |
| set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags); |
| } |
| |
| static int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask) |
| { |
| LIST_HEAD(tmp_links); |
| struct cgroup *root_cgrp = &root->cgrp; |
| struct css_set *cset; |
| int i, ret; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| ret = cgroup_idr_alloc(&root->cgroup_idr, root_cgrp, 1, 2, GFP_KERNEL); |
| if (ret < 0) |
| goto out; |
| root_cgrp->id = ret; |
| root_cgrp->ancestor_ids[0] = ret; |
| |
| ret = percpu_ref_init(&root_cgrp->self.refcnt, css_release, 0, |
| GFP_KERNEL); |
| if (ret) |
| goto out; |
| |
| /* |
| * We're accessing css_set_count without locking css_set_lock here, |
| * but that's OK - it can only be increased by someone holding |
| * cgroup_lock, and that's us. Later rebinding may disable |
| * controllers on the default hierarchy and thus create new csets, |
| * which can't be more than the existing ones. Allocate 2x. |
| */ |
| ret = allocate_cgrp_cset_links(2 * css_set_count, &tmp_links); |
| if (ret) |
| goto cancel_ref; |
| |
| ret = cgroup_init_root_id(root); |
| if (ret) |
| goto cancel_ref; |
| |
| root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops, |
| KERNFS_ROOT_CREATE_DEACTIVATED, |
| root_cgrp); |
| if (IS_ERR(root->kf_root)) { |
| ret = PTR_ERR(root->kf_root); |
| goto exit_root_id; |
| } |
| root_cgrp->kn = root->kf_root->kn; |
| |
| ret = css_populate_dir(&root_cgrp->self); |
| if (ret) |
| goto destroy_root; |
| |
| ret = rebind_subsystems(root, ss_mask); |
| if (ret) |
| goto destroy_root; |
| |
| /* |
| * There must be no failure case after here, since rebinding takes |
| * care of subsystems' refcounts, which are explicitly dropped in |
| * the failure exit path. |
| */ |
| list_add(&root->root_list, &cgroup_roots); |
| cgroup_root_count++; |
| |
| /* |
| * Link the root cgroup in this hierarchy into all the css_set |
| * objects. |
| */ |
| spin_lock_irq(&css_set_lock); |
| hash_for_each(css_set_table, i, cset, hlist) { |
| link_css_set(&tmp_links, cset, root_cgrp); |
| if (css_set_populated(cset)) |
| cgroup_update_populated(root_cgrp, true); |
| } |
| spin_unlock_irq(&css_set_lock); |
| |
| BUG_ON(!list_empty(&root_cgrp->self.children)); |
| BUG_ON(atomic_read(&root->nr_cgrps) != 1); |
| |
| kernfs_activate(root_cgrp->kn); |
| ret = 0; |
| goto out; |
| |
| destroy_root: |
| kernfs_destroy_root(root->kf_root); |
| root->kf_root = NULL; |
| exit_root_id: |
| cgroup_exit_root_id(root); |
| cancel_ref: |
| percpu_ref_exit(&root_cgrp->self.refcnt); |
| out: |
| free_cgrp_cset_links(&tmp_links); |
| return ret; |
| } |
| |
| static struct dentry *cgroup_mount(struct file_system_type *fs_type, |
| int flags, const char *unused_dev_name, |
| void *data) |
| { |
| bool is_v2 = fs_type == &cgroup2_fs_type; |
| struct super_block *pinned_sb = NULL; |
| struct cgroup_namespace *ns = current->nsproxy->cgroup_ns; |
| struct cgroup_subsys *ss; |
| struct cgroup_root *root; |
| struct cgroup_sb_opts opts; |
| struct dentry *dentry; |
| int ret; |
| int i; |
| bool new_sb; |
| |
| get_cgroup_ns(ns); |
| |
| /* Check if the caller has permission to mount. */ |
| if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN)) { |
| put_cgroup_ns(ns); |
| return ERR_PTR(-EPERM); |
| } |
| |
| /* |
| * The first time anyone tries to mount a cgroup, enable the list |
| * linking each css_set to its tasks and fix up all existing tasks. |
| */ |
| if (!use_task_css_set_links) |
| cgroup_enable_task_cg_lists(); |
| |
| if (is_v2) { |
| if (data) { |
| pr_err("cgroup2: unknown option \"%s\"\n", (char *)data); |
| put_cgroup_ns(ns); |
| return ERR_PTR(-EINVAL); |
| } |
| cgrp_dfl_visible = true; |
| root = &cgrp_dfl_root; |
| cgroup_get(&root->cgrp); |
| goto out_mount; |
| } |
| |
| cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp); |
| |
| /* First find the desired set of subsystems */ |
| ret = parse_cgroupfs_options(data, &opts); |
| if (ret) |
| goto out_unlock; |
| |
| /* |
| * Destruction of cgroup root is asynchronous, so subsystems may |
| * still be dying after the previous unmount. Let's drain the |
| * dying subsystems. We just need to ensure that the ones |
| * unmounted previously finish dying and don't care about new ones |
| * starting. Testing ref liveliness is good enough. |
| */ |
| for_each_subsys(ss, i) { |
| if (!(opts.subsys_mask & (1 << i)) || |
| ss->root == &cgrp_dfl_root) |
| continue; |
| |
| if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) { |
| mutex_unlock(&cgroup_mutex); |
| msleep(10); |
| ret = restart_syscall(); |
| goto out_free; |
| } |
| cgroup_put(&ss->root->cgrp); |
| } |
| |
| for_each_root(root) { |
| bool name_match = false; |
| |
| if (root == &cgrp_dfl_root) |
| continue; |
| |
| /* |
| * If we asked for a name then it must match. Also, if |
| * name matches but sybsys_mask doesn't, we should fail. |
| * Remember whether name matched. |
| */ |
| if (opts.name) { |
| if (strcmp(opts.name, root->name)) |
| continue; |
| name_match = true; |
| } |
| |
| /* |
| * If we asked for subsystems (or explicitly for no |
| * subsystems) then they must match. |
| */ |
| if ((opts.subsys_mask || opts.none) && |
| (opts.subsys_mask != root->subsys_mask)) { |
| if (!name_match) |
| continue; |
| ret = -EBUSY; |
| goto out_unlock; |
| } |
| |
| if (root->flags ^ opts.flags) |
| pr_warn("new mount options do not match the existing superblock, will be ignored\n"); |
| |
| /* |
| * We want to reuse @root whose lifetime is governed by its |
| * ->cgrp. Let's check whether @root is alive and keep it |
| * that way. As cgroup_kill_sb() can happen anytime, we |
| * want to block it by pinning the sb so that @root doesn't |
| * get killed before mount is complete. |
| * |
| * With the sb pinned, tryget_live can reliably indicate |
| * whether @root can be reused. If it's being killed, |
| * drain it. We can use wait_queue for the wait but this |
| * path is super cold. Let's just sleep a bit and retry. |
| */ |
| pinned_sb = kernfs_pin_sb(root->kf_root, NULL); |
| if (IS_ERR(pinned_sb) || |
| !percpu_ref_tryget_live(&root->cgrp.self.refcnt)) { |
| mutex_unlock(&cgroup_mutex); |
| if (!IS_ERR_OR_NULL(pinned_sb)) |
| deactivate_super(pinned_sb); |
| msleep(10); |
| ret = restart_syscall(); |
| goto out_free; |
| } |
| |
| ret = 0; |
| goto out_unlock; |
| } |
| |
| /* |
| * No such thing, create a new one. name= matching without subsys |
| * specification is allowed for already existing hierarchies but we |
| * can't create new one without subsys specification. |
| */ |
| if (!opts.subsys_mask && !opts.none) { |
| ret = -EINVAL; |
| goto out_unlock; |
| } |
| |
| /* Hierarchies may only be created in the initial cgroup namespace. */ |
| if (ns != &init_cgroup_ns) { |
| ret = -EPERM; |
| goto out_unlock; |
| } |
| |
| root = kzalloc(sizeof(*root), GFP_KERNEL); |
| if (!root) { |
| ret = -ENOMEM; |
| goto out_unlock; |
| } |
| |
| init_cgroup_root(root, &opts); |
| |
| ret = cgroup_setup_root(root, opts.subsys_mask); |
| if (ret) |
| cgroup_free_root(root); |
| |
| out_unlock: |
| mutex_unlock(&cgroup_mutex); |
| out_free: |
| kfree(opts.release_agent); |
| kfree(opts.name); |
| |
| if (ret) { |
| put_cgroup_ns(ns); |
| return ERR_PTR(ret); |
| } |
| out_mount: |
| dentry = kernfs_mount(fs_type, flags, root->kf_root, |
| is_v2 ? CGROUP2_SUPER_MAGIC : CGROUP_SUPER_MAGIC, |
| &new_sb); |
| |
| /* |
| * In non-init cgroup namespace, instead of root cgroup's |
| * dentry, we return the dentry corresponding to the |
| * cgroupns->root_cgrp. |
| */ |
| if (!IS_ERR(dentry) && ns != &init_cgroup_ns) { |
| struct dentry *nsdentry; |
| struct cgroup *cgrp; |
| |
| mutex_lock(&cgroup_mutex); |
| spin_lock_irq(&css_set_lock); |
| |
| cgrp = cset_cgroup_from_root(ns->root_cset, root); |
| |
| spin_unlock_irq(&css_set_lock); |
| mutex_unlock(&cgroup_mutex); |
| |
| nsdentry = kernfs_node_dentry(cgrp->kn, dentry->d_sb); |
| dput(dentry); |
| dentry = nsdentry; |
| } |
| |
| if (IS_ERR(dentry) || !new_sb) |
| cgroup_put(&root->cgrp); |
| |
| /* |
| * If @pinned_sb, we're reusing an existing root and holding an |
| * extra ref on its sb. Mount is complete. Put the extra ref. |
| */ |
| if (pinned_sb) { |
| WARN_ON(new_sb); |
| deactivate_super(pinned_sb); |
| } |
| |
| put_cgroup_ns(ns); |
| return dentry; |
| } |
| |
| static void cgroup_kill_sb(struct super_block *sb) |
| { |
| struct kernfs_root *kf_root = kernfs_root_from_sb(sb); |
| struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
| |
| /* |
| * If @root doesn't have any mounts or children, start killing it. |
| * This prevents new mounts by disabling percpu_ref_tryget_live(). |
| * cgroup_mount() may wait for @root's release. |
| * |
| * And don't kill the default root. |
| */ |
| if (!list_empty(&root->cgrp.self.children) || |
| root == &cgrp_dfl_root) |
| cgroup_put(&root->cgrp); |
| else |
| percpu_ref_kill(&root->cgrp.self.refcnt); |
| |
| kernfs_kill_sb(sb); |
| } |
| |
| static struct file_system_type cgroup_fs_type = { |
| .name = "cgroup", |
| .mount = cgroup_mount, |
| .kill_sb = cgroup_kill_sb, |
| .fs_flags = FS_USERNS_MOUNT, |
| }; |
| |
| static struct file_system_type cgroup2_fs_type = { |
| .name = "cgroup2", |
| .mount = cgroup_mount, |
| .kill_sb = cgroup_kill_sb, |
| .fs_flags = FS_USERNS_MOUNT, |
| }; |
| |
| static char *cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen, |
| struct cgroup_namespace *ns) |
| { |
| struct cgroup *root = cset_cgroup_from_root(ns->root_cset, cgrp->root); |
| int ret; |
| |
| ret = kernfs_path_from_node(cgrp->kn, root->kn, buf, buflen); |
| if (ret < 0 || ret >= buflen) |
| return NULL; |
| return buf; |
| } |
| |
| char *cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen, |
| struct cgroup_namespace *ns) |
| { |
| char *ret; |
| |
| mutex_lock(&cgroup_mutex); |
| spin_lock_irq(&css_set_lock); |
| |
| ret = cgroup_path_ns_locked(cgrp, buf, buflen, ns); |
| |
| spin_unlock_irq(&css_set_lock); |
| mutex_unlock(&cgroup_mutex); |
| |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(cgroup_path_ns); |
| |
| /** |
| * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy |
| * @task: target task |
| * @buf: the buffer to write the path into |
| * @buflen: the length of the buffer |
| * |
| * Determine @task's cgroup on the first (the one with the lowest non-zero |
| * hierarchy_id) cgroup hierarchy and copy its path into @buf. This |
| * function grabs cgroup_mutex and shouldn't be used inside locks used by |
| * cgroup controller callbacks. |
| * |
| * Return value is the same as kernfs_path(). |
| */ |
| char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen) |
| { |
| struct cgroup_root *root; |
| struct cgroup *cgrp; |
| int hierarchy_id = 1; |
| char *path = NULL; |
| |
| mutex_lock(&cgroup_mutex); |
| spin_lock_irq(&css_set_lock); |
| |
| root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id); |
| |
| if (root) { |
| cgrp = task_cgroup_from_root(task, root); |
| path = cgroup_path_ns_locked(cgrp, buf, buflen, &init_cgroup_ns); |
| } else { |
| /* if no hierarchy exists, everyone is in "/" */ |
| if (strlcpy(buf, "/", buflen) < buflen) |
| path = buf; |
| } |
| |
| spin_unlock_irq(&css_set_lock); |
| mutex_unlock(&cgroup_mutex); |
| return path; |
| } |
| EXPORT_SYMBOL_GPL(task_cgroup_path); |
| |
| /* used to track tasks and other necessary states during migration */ |
| struct cgroup_taskset { |
| /* the src and dst cset list running through cset->mg_node */ |
| struct list_head src_csets; |
| struct list_head dst_csets; |
| |
| /* the subsys currently being processed */ |
| int ssid; |
| |
| /* |
| * Fields for cgroup_taskset_*() iteration. |
| * |
| * Before migration is committed, the target migration tasks are on |
| * ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of |
| * the csets on ->dst_csets. ->csets point to either ->src_csets |
| * or ->dst_csets depending on whether migration is committed. |
| * |
| * ->cur_csets and ->cur_task point to the current task position |
| * during iteration. |
| */ |
| struct list_head *csets; |
| struct css_set *cur_cset; |
| struct task_struct *cur_task; |
| }; |
| |
| #define CGROUP_TASKSET_INIT(tset) (struct cgroup_taskset){ \ |
| .src_csets = LIST_HEAD_INIT(tset.src_csets), \ |
| .dst_csets = LIST_HEAD_INIT(tset.dst_csets), \ |
| .csets = &tset.src_csets, \ |
| } |
| |
| /** |
| * cgroup_taskset_add - try to add a migration target task to a taskset |
| * @task: target task |
| * @tset: target taskset |
| * |
| * Add @task, which is a migration target, to @tset. This function becomes |
| * noop if @task doesn't need to be migrated. @task's css_set should have |
| * been added as a migration source and @task->cg_list will be moved from |
| * the css_set's tasks list to mg_tasks one. |
| */ |
| static void cgroup_taskset_add(struct task_struct *task, |
| struct cgroup_taskset *tset) |
| { |
| struct css_set *cset; |
| |
| lockdep_assert_held(&css_set_lock); |
| |
| /* @task either already exited or can't exit until the end */ |
| if (task->flags & PF_EXITING) |
| return; |
| |
| /* leave @task alone if post_fork() hasn't linked it yet */ |
| if (list_empty(&task->cg_list)) |
| return; |
| |
| cset = task_css_set(task); |
| if (!cset->mg_src_cgrp) |
| return; |
| |
| list_move_tail(&task->cg_list, &cset->mg_tasks); |
| if (list_empty(&cset->mg_node)) |
| list_add_tail(&cset->mg_node, &tset->src_csets); |
| if (list_empty(&cset->mg_dst_cset->mg_node)) |
| list_move_tail(&cset->mg_dst_cset->mg_node, |
| &tset->dst_csets); |
| } |
| |
| /** |
| * cgroup_taskset_first - reset taskset and return the first task |
| * @tset: taskset of interest |
| * @dst_cssp: output variable for the destination css |
| * |
| * @tset iteration is initialized and the first task is returned. |
| */ |
| struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset, |
| struct cgroup_subsys_state **dst_cssp) |
| { |
| tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node); |
| tset->cur_task = NULL; |
| |
| return cgroup_taskset_next(tset, dst_cssp); |
| } |
| |
| /** |
| * cgroup_taskset_next - iterate to the next task in taskset |
| * @tset: taskset of interest |
| * @dst_cssp: output variable for the destination css |
| * |
| * Return the next task in @tset. Iteration must have been initialized |
| * with cgroup_taskset_first(). |
| */ |
| struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset, |
| struct cgroup_subsys_state **dst_cssp) |
| { |
| struct css_set *cset = tset->cur_cset; |
| struct task_struct *task = tset->cur_task; |
| |
| while (&cset->mg_node != tset->csets) { |
| if (!task) |
| task = list_first_entry(&cset->mg_tasks, |
| struct task_struct, cg_list); |
| else |
| task = list_next_entry(task, cg_list); |
| |
| if (&task->cg_list != &cset->mg_tasks) { |
| tset->cur_cset = cset; |
| tset->cur_task = task; |
| |
| /* |
| * This function may be called both before and |
| * after cgroup_taskset_migrate(). The two cases |
| * can be distinguished by looking at whether @cset |
| * has its ->mg_dst_cset set. |
| */ |
| if (cset->mg_dst_cset) |
| *dst_cssp = cset->mg_dst_cset->subsys[tset->ssid]; |
| else |
| *dst_cssp = cset->subsys[tset->ssid]; |
| |
| return task; |
| } |
| |
| cset = list_next_entry(cset, mg_node); |
| task = NULL; |
| } |
| |
| return NULL; |
| } |
| |
| /** |
| * cgroup_taskset_migrate - migrate a taskset |
| * @tset: taget taskset |
| * @root: cgroup root the migration is taking place on |
| * |
| * Migrate tasks in @tset as setup by migration preparation functions. |
| * This function fails iff one of the ->can_attach callbacks fails and |
| * guarantees that either all or none of the tasks in @tset are migrated. |
| * @tset is consumed regardless of success. |
| */ |
| static int cgroup_taskset_migrate(struct cgroup_taskset *tset, |
| struct cgroup_root *root) |
| { |
| struct cgroup_subsys *ss; |
| struct task_struct *task, *tmp_task; |
| struct css_set *cset, *tmp_cset; |
| int ssid, failed_ssid, ret; |
| |
| /* methods shouldn't be called if no task is actually migrating */ |
| if (list_empty(&tset->src_csets)) |
| return 0; |
| |
| /* check that we can legitimately attach to the cgroup */ |
| do_each_subsys_mask(ss, ssid, root->subsys_mask) { |
| if (ss->can_attach) { |
| tset->ssid = ssid; |
| ret = ss->can_attach(tset); |
| if (ret) { |
| failed_ssid = ssid; |
| goto out_cancel_attach; |
| } |
| } |
| } while_each_subsys_mask(); |
| |
| /* |
| * Now that we're guaranteed success, proceed to move all tasks to |
| * the new cgroup. There are no failure cases after here, so this |
| * is the commit point. |
| */ |
| spin_lock_irq(&css_set_lock); |
| list_for_each_entry(cset, &tset->src_csets, mg_node) { |
| list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list) { |
| struct css_set *from_cset = task_css_set(task); |
| struct css_set *to_cset = cset->mg_dst_cset; |
| |
| get_css_set(to_cset); |
| css_set_move_task(task, from_cset, to_cset, true); |
| put_css_set_locked(from_cset); |
| } |
| } |
| spin_unlock_irq(&css_set_lock); |
| |
| /* |
| * Migration is committed, all target tasks are now on dst_csets. |
| * Nothing is sensitive to fork() after this point. Notify |
| * controllers that migration is complete. |
| */ |
| tset->csets = &tset->dst_csets; |
| |
| do_each_subsys_mask(ss, ssid, root->subsys_mask) { |
| if (ss->attach) { |
| tset->ssid = ssid; |
| ss->attach(tset); |
| } |
| } while_each_subsys_mask(); |
| |
| ret = 0; |
| goto out_release_tset; |
| |
| out_cancel_attach: |
| do_each_subsys_mask(ss, ssid, root->subsys_mask) { |
| if (ssid == failed_ssid) |
| break; |
| if (ss->cancel_attach) { |
| tset->ssid = ssid; |
| ss->cancel_attach(tset); |
| } |
| } while_each_subsys_mask(); |
| out_release_tset: |
| spin_lock_irq(&css_set_lock); |
| list_splice_init(&tset->dst_csets, &tset->src_csets); |
| list_for_each_entry_safe(cset, tmp_cset, &tset->src_csets, mg_node) { |
| list_splice_tail_init(&cset->mg_tasks, &cset->tasks); |
| list_del_init(&cset->mg_node); |
| } |
| spin_unlock_irq(&css_set_lock); |
| return ret; |
| } |
| |
| /** |
| * cgroup_may_migrate_to - verify whether a cgroup can be migration destination |
| * @dst_cgrp: destination cgroup to test |
| * |
| * On the default hierarchy, except for the root, subtree_control must be |
| * zero for migration destination cgroups with tasks so that child cgroups |
| * don't compete against tasks. |
| */ |
| static bool cgroup_may_migrate_to(struct cgroup *dst_cgrp) |
| { |
| return !cgroup_on_dfl(dst_cgrp) || !cgroup_parent(dst_cgrp) || |
| !dst_cgrp->subtree_control; |
| } |
| |
| /** |
| * cgroup_migrate_finish - cleanup after attach |
| * @preloaded_csets: list of preloaded css_sets |
| * |
| * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See |
| * those functions for details. |
| */ |
| static void cgroup_migrate_finish(struct list_head *preloaded_csets) |
| { |
| struct css_set *cset, *tmp_cset; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| spin_lock_irq(&css_set_lock); |
| list_for_each_entry_safe(cset, tmp_cset, preloaded_csets, mg_preload_node) { |
| cset->mg_src_cgrp = NULL; |
| cset->mg_dst_cgrp = NULL; |
| cset->mg_dst_cset = NULL; |
| list_del_init(&cset->mg_preload_node); |
| put_css_set_locked(cset); |
| } |
| spin_unlock_irq(&css_set_lock); |
| } |
| |
| /** |
| * cgroup_migrate_add_src - add a migration source css_set |
| * @src_cset: the source css_set to add |
| * @dst_cgrp: the destination cgroup |
| * @preloaded_csets: list of preloaded css_sets |
| * |
| * Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin |
| * @src_cset and add it to @preloaded_csets, which should later be cleaned |
| * up by cgroup_migrate_finish(). |
| * |
| * This function may be called without holding cgroup_threadgroup_rwsem |
| * even if the target is a process. Threads may be created and destroyed |
| * but as long as cgroup_mutex is not dropped, no new css_set can be put |
| * into play and the preloaded css_sets are guaranteed to cover all |
| * migrations. |
| */ |
| static void cgroup_migrate_add_src(struct css_set *src_cset, |
| struct cgroup *dst_cgrp, |
| struct list_head *preloaded_csets) |
| { |
| struct cgroup *src_cgrp; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| lockdep_assert_held(&css_set_lock); |
| |
| /* |
| * If ->dead, @src_set is associated with one or more dead cgroups |
| * and doesn't contain any migratable tasks. Ignore it early so |
| * that the rest of migration path doesn't get confused by it. |
| */ |
| if (src_cset->dead) |
| return; |
| |
| src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root); |
| |
| if (!list_empty(&src_cset->mg_preload_node)) |
| return; |
| |
| WARN_ON(src_cset->mg_src_cgrp); |
| WARN_ON(src_cset->mg_dst_cgrp); |
| WARN_ON(!list_empty(&src_cset->mg_tasks)); |
| WARN_ON(!list_empty(&src_cset->mg_node)); |
| |
| src_cset->mg_src_cgrp = src_cgrp; |
| src_cset->mg_dst_cgrp = dst_cgrp; |
| get_css_set(src_cset); |
| list_add(&src_cset->mg_preload_node, preloaded_csets); |
| } |
| |
| /** |
| * cgroup_migrate_prepare_dst - prepare destination css_sets for migration |
| * @preloaded_csets: list of preloaded source css_sets |
| * |
| * Tasks are about to be moved and all the source css_sets have been |
| * preloaded to @preloaded_csets. This function looks up and pins all |
| * destination css_sets, links each to its source, and append them to |
| * @preloaded_csets. |
| * |
| * This function must be called after cgroup_migrate_add_src() has been |
| * called on each migration source css_set. After migration is performed |
| * using cgroup_migrate(), cgroup_migrate_finish() must be called on |
| * @preloaded_csets. |
| */ |
| static int cgroup_migrate_prepare_dst(struct list_head *preloaded_csets) |
| { |
| LIST_HEAD(csets); |
| struct css_set *src_cset, *tmp_cset; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| /* look up the dst cset for each src cset and link it to src */ |
| list_for_each_entry_safe(src_cset, tmp_cset, preloaded_csets, mg_preload_node) { |
| struct css_set *dst_cset; |
| |
| dst_cset = find_css_set(src_cset, src_cset->mg_dst_cgrp); |
| if (!dst_cset) |
| goto err; |
| |
| WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset); |
| |
| /* |
| * If src cset equals dst, it's noop. Drop the src. |
| * cgroup_migrate() will skip the cset too. Note that we |
| * can't handle src == dst as some nodes are used by both. |
| */ |
| if (src_cset == dst_cset) { |
| src_cset->mg_src_cgrp = NULL; |
| src_cset->mg_dst_cgrp = NULL; |
| list_del_init(&src_cset->mg_preload_node); |
| put_css_set(src_cset); |
| put_css_set(dst_cset); |
| continue; |
| } |
| |
| src_cset->mg_dst_cset = dst_cset; |
| |
| if (list_empty(&dst_cset->mg_preload_node)) |
| list_add(&dst_cset->mg_preload_node, &csets); |
| else |
| put_css_set(dst_cset); |
| } |
| |
| list_splice_tail(&csets, preloaded_csets); |
| return 0; |
| err: |
| cgroup_migrate_finish(&csets); |
| return -ENOMEM; |
| } |
| |
| /** |
| * cgroup_migrate - migrate a process or task to a cgroup |
| * @leader: the leader of the process or the task to migrate |
| * @threadgroup: whether @leader points to the whole process or a single task |
| * @root: cgroup root migration is taking place on |
| * |
| * Migrate a process or task denoted by @leader. If migrating a process, |
| * the caller must be holding cgroup_threadgroup_rwsem. The caller is also |
| * responsible for invoking cgroup_migrate_add_src() and |
| * cgroup_migrate_prepare_dst() on the targets before invoking this |
| * function and following up with cgroup_migrate_finish(). |
| * |
| * As long as a controller's ->can_attach() doesn't fail, this function is |
| * guaranteed to succeed. This means that, excluding ->can_attach() |
| * failure, when migrating multiple targets, the success or failure can be |
| * decided for all targets by invoking group_migrate_prepare_dst() before |
| * actually starting migrating. |
| */ |
| static int cgroup_migrate(struct task_struct *leader, bool threadgroup, |
| struct cgroup_root *root) |
| { |
| struct cgroup_taskset tset = CGROUP_TASKSET_INIT(tset); |
| struct task_struct *task; |
| |
| /* |
| * Prevent freeing of tasks while we take a snapshot. Tasks that are |
| * already PF_EXITING could be freed from underneath us unless we |
| * take an rcu_read_lock. |
| */ |
| spin_lock_irq(&css_set_lock); |
| rcu_read_lock(); |
| task = leader; |
| do { |
| cgroup_taskset_add(task, &tset); |
| if (!threadgroup) |
| break; |
| } while_each_thread(leader, task); |
| rcu_read_unlock(); |
| spin_unlock_irq(&css_set_lock); |
| |
| return cgroup_taskset_migrate(&tset, root); |
| } |
| |
| /** |
| * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup |
| * @dst_cgrp: the cgroup to attach to |
| * @leader: the task or the leader of the threadgroup to be attached |
| * @threadgroup: attach the whole threadgroup? |
| * |
| * Call holding cgroup_mutex and cgroup_threadgroup_rwsem. |
| */ |
| static int cgroup_attach_task(struct cgroup *dst_cgrp, |
| struct task_struct *leader, bool threadgroup) |
| { |
| LIST_HEAD(preloaded_csets); |
| struct task_struct *task; |
| int ret; |
| |
| if (!cgroup_may_migrate_to(dst_cgrp)) |
| return -EBUSY; |
| |
| /* look up all src csets */ |
| spin_lock_irq(&css_set_lock); |
| rcu_read_lock(); |
| task = leader; |
| do { |
| cgroup_migrate_add_src(task_css_set(task), dst_cgrp, |
| &preloaded_csets); |
| if (!threadgroup) |
| break; |
| } while_each_thread(leader, task); |
| rcu_read_unlock(); |
| spin_unlock_irq(&css_set_lock); |
| |
| /* prepare dst csets and commit */ |
| ret = cgroup_migrate_prepare_dst(&preloaded_csets); |
| if (!ret) |
| ret = cgroup_migrate(leader, threadgroup, dst_cgrp->root); |
| |
| cgroup_migrate_finish(&preloaded_csets); |
| return ret; |
| } |
| |
| static int cgroup_procs_write_permission(struct task_struct *task, |
| struct cgroup *dst_cgrp, |
| struct kernfs_open_file *of) |
| { |
| const struct cred *cred = current_cred(); |
| const struct cred *tcred = get_task_cred(task); |
| int ret = 0; |
| |
| /* |
| * even if we're attaching all tasks in the thread group, we only |
| * need to check permissions on one of them. |
| */ |
| if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) && |
| !uid_eq(cred->euid, tcred->uid) && |
| !uid_eq(cred->euid, tcred->suid)) |
| ret = -EACCES; |
| |
| if (!ret && cgroup_on_dfl(dst_cgrp)) { |
| struct super_block *sb = of->file->f_path.dentry->d_sb; |
| struct cgroup *cgrp; |
| struct inode *inode; |
| |
| spin_lock_irq(&css_set_lock); |
| cgrp = task_cgroup_from_root(task, &cgrp_dfl_root); |
| spin_unlock_irq(&css_set_lock); |
| |
| while (!cgroup_is_descendant(dst_cgrp, cgrp)) |
| cgrp = cgroup_parent(cgrp); |
| |
| ret = -ENOMEM; |
| inode = kernfs_get_inode(sb, cgrp->procs_file.kn); |
| if (inode) { |
| ret = inode_permission(inode, MAY_WRITE); |
| iput(inode); |
| } |
| } |
| |
| put_cred(tcred); |
| return ret; |
| } |
| |
| /* |
| * Find the task_struct of the task to attach by vpid and pass it along to the |
| * function to attach either it or all tasks in its threadgroup. Will lock |
| * cgroup_mutex and threadgroup. |
| */ |
| static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf, |
| size_t nbytes, loff_t off, bool threadgroup) |
| { |
| struct task_struct *tsk; |
| struct cgroup_subsys *ss; |
| struct cgroup *cgrp; |
| pid_t pid; |
| int ssid, ret; |
| |
| if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0) |
| return -EINVAL; |
| |
| cgrp = cgroup_kn_lock_live(of->kn, false); |
| if (!cgrp) |
| return -ENODEV; |
| |
| percpu_down_write(&cgroup_threadgroup_rwsem); |
| rcu_read_lock(); |
| if (pid) { |
| tsk = find_task_by_vpid(pid); |
| if (!tsk) { |
| ret = -ESRCH; |
| goto out_unlock_rcu; |
| } |
| } else { |
| tsk = current; |
| } |
| |
| if (threadgroup) |
| tsk = tsk->group_leader; |
| |
| /* |
| * Workqueue threads may acquire PF_NO_SETAFFINITY and become |
| * trapped in a cpuset, or RT worker may be born in a cgroup |
| * with no rt_runtime allocated. Just say no. |
| */ |
| if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) { |
| ret = -EINVAL; |
| goto out_unlock_rcu; |
| } |
| |
| get_task_struct(tsk); |
| rcu_read_unlock(); |
| |
| ret = cgroup_procs_write_permission(tsk, cgrp, of); |
| if (!ret) |
| ret = cgroup_attach_task(cgrp, tsk, threadgroup); |
| |
| put_task_struct(tsk); |
| goto out_unlock_threadgroup; |
| |
| out_unlock_rcu: |
| rcu_read_unlock(); |
| out_unlock_threadgroup: |
| percpu_up_write(&cgroup_threadgroup_rwsem); |
| for_each_subsys(ss, ssid) |
| if (ss->post_attach) |
| ss->post_attach(); |
| cgroup_kn_unlock(of->kn); |
| return ret ?: nbytes; |
| } |
| |
| /** |
| * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' |
| * @from: attach to all cgroups of a given task |
| * @tsk: the task to be attached |
| */ |
| int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) |
| { |
| struct cgroup_root *root; |
| int retval = 0; |
| |
| mutex_lock(&cgroup_mutex); |
| percpu_down_write(&cgroup_threadgroup_rwsem); |
| for_each_root(root) { |
| struct cgroup *from_cgrp; |
| |
| if (root == &cgrp_dfl_root) |
| continue; |
| |
| spin_lock_irq(&css_set_lock); |
| from_cgrp = task_cgroup_from_root(from, root); |
| spin_unlock_irq(&css_set_lock); |
| |
| retval = cgroup_attach_task(from_cgrp, tsk, false); |
| if (retval) |
| break; |
| } |
| percpu_up_write(&cgroup_threadgroup_rwsem); |
| mutex_unlock(&cgroup_mutex); |
| |
| return retval; |
| } |
| EXPORT_SYMBOL_GPL(cgroup_attach_task_all); |
| |
| static ssize_t cgroup_tasks_write(struct kernfs_open_file *of, |
| char *buf, size_t nbytes, loff_t off) |
| { |
| return __cgroup_procs_write(of, buf, nbytes, off, false); |
| } |
| |
| static ssize_t cgroup_procs_write(struct kernfs_open_file *of, |
| char *buf, size_t nbytes, loff_t off) |
| { |
| return __cgroup_procs_write(of, buf, nbytes, off, true); |
| } |
| |
| static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of, |
| char *buf, size_t nbytes, loff_t off) |
| { |
| struct cgroup *cgrp; |
| |
| BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); |
| |
| cgrp = cgroup_kn_lock_live(of->kn, false); |
| if (!cgrp) |
| return -ENODEV; |
| spin_lock(&release_agent_path_lock); |
| strlcpy(cgrp->root->release_agent_path, strstrip(buf), |
| sizeof(cgrp->root->release_agent_path)); |
| spin_unlock(&release_agent_path_lock); |
| cgroup_kn_unlock(of->kn); |
| return nbytes; |
| } |
| |
| static int cgroup_release_agent_show(struct seq_file *seq, void *v) |
| { |
| struct cgroup *cgrp = seq_css(seq)->cgroup; |
| |
| spin_lock(&release_agent_path_lock); |
| seq_puts(seq, cgrp->root->release_agent_path); |
| spin_unlock(&release_agent_path_lock); |
| seq_putc(seq, '\n'); |
| return 0; |
| } |
| |
| static int cgroup_sane_behavior_show(struct seq_file *seq, void *v) |
| { |
| seq_puts(seq, "0\n"); |
| return 0; |
| } |
| |
| static void cgroup_print_ss_mask(struct seq_file *seq, u16 ss_mask) |
| { |
| struct cgroup_subsys *ss; |
| bool printed = false; |
| int ssid; |
| |
| do_each_subsys_mask(ss, ssid, ss_mask) { |
| if (printed) |
| seq_putc(seq, ' '); |
| seq_printf(seq, "%s", ss->name); |
| printed = true; |
| } while_each_subsys_mask(); |
| if (printed) |
| seq_putc(seq, '\n'); |
| } |
| |
| /* show controllers which are enabled from the parent */ |
| static int cgroup_controllers_show(struct seq_file *seq, void *v) |
| { |
| struct cgroup *cgrp = seq_css(seq)->cgroup; |
| |
| cgroup_print_ss_mask(seq, cgroup_control(cgrp)); |
| return 0; |
| } |
| |
| /* show controllers which are enabled for a given cgroup's children */ |
| static int cgroup_subtree_control_show(struct seq_file *seq, void *v) |
| { |
| struct cgroup *cgrp = seq_css(seq)->cgroup; |
| |
| cgroup_print_ss_mask(seq, cgrp->subtree_control); |
| return 0; |
| } |
| |
| /** |
| * cgroup_update_dfl_csses - update css assoc of a subtree in default hierarchy |
| * @cgrp: root of the subtree to update csses for |
| * |
| * @cgrp's control masks have changed and its subtree's css associations |
| * need to be updated accordingly. This function looks up all css_sets |
| * which are attached to the subtree, creates the matching updated css_sets |
| * and migrates the tasks to the new ones. |
| */ |
| static int cgroup_update_dfl_csses(struct cgroup *cgrp) |
| { |
| LIST_HEAD(preloaded_csets); |
| struct cgroup_taskset tset = CGROUP_TASKSET_INIT(tset); |
| struct cgroup_subsys_state *d_css; |
| struct cgroup *dsct; |
| struct css_set *src_cset; |
| int ret; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| percpu_down_write(&cgroup_threadgroup_rwsem); |
| |
| /* look up all csses currently attached to @cgrp's subtree */ |
| spin_lock_irq(&css_set_lock); |
| cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) { |
| struct cgrp_cset_link *link; |
| |
| list_for_each_entry(link, &dsct->cset_links, cset_link) |
| cgroup_migrate_add_src(link->cset, dsct, |
| &preloaded_csets); |
| } |
| spin_unlock_irq(&css_set_lock); |
| |
| /* NULL dst indicates self on default hierarchy */ |
| ret = cgroup_migrate_prepare_dst(&preloaded_csets); |
| if (ret) |
| goto out_finish; |
| |
| spin_lock_irq(&css_set_lock); |
| list_for_each_entry(src_cset, &preloaded_csets, mg_preload_node) { |
| struct task_struct *task, *ntask; |
| |
| /* src_csets precede dst_csets, break on the first dst_cset */ |
| if (!src_cset->mg_src_cgrp) |
| break; |
| |
| /* all tasks in src_csets need to be migrated */ |
| list_for_each_entry_safe(task, ntask, &src_cset->tasks, cg_list) |
| cgroup_taskset_add(task, &tset); |
| } |
| spin_unlock_irq(&css_set_lock); |
| |
| ret = cgroup_taskset_migrate(&tset, cgrp->root); |
| out_finish: |
| cgroup_migrate_finish(&preloaded_csets); |
| percpu_up_write(&cgroup_threadgroup_rwsem); |
| return ret; |
| } |
| |
| /** |
| * cgroup_lock_and_drain_offline - lock cgroup_mutex and drain offlined csses |
| * @cgrp: root of the target subtree |
| * |
| * Because css offlining is asynchronous, userland may try to re-enable a |
| * controller while the previous css is still around. This function grabs |
| * cgroup_mutex and drains the previous css instances of @cgrp's subtree. |
| */ |
| static void cgroup_lock_and_drain_offline(struct cgroup *cgrp) |
| __acquires(&cgroup_mutex) |
| { |
| struct cgroup *dsct; |
| struct cgroup_subsys_state *d_css; |
| struct cgroup_subsys *ss; |
| int ssid; |
| |
| restart: |
| mutex_lock(&cgroup_mutex); |
| |
| cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) { |
| for_each_subsys(ss, ssid) { |
| struct cgroup_subsys_state *css = cgroup_css(dsct, ss); |
| DEFINE_WAIT(wait); |
| |
| if (!css || !percpu_ref_is_dying(&css->refcnt)) |
| continue; |
| |
| cgroup_get(dsct); |
| prepare_to_wait(&dsct->offline_waitq, &wait, |
| TASK_UNINTERRUPTIBLE); |
| |
| mutex_unlock(&cgroup_mutex); |
| schedule(); |
| finish_wait(&dsct->offline_waitq, &wait); |
| |
| cgroup_put(dsct); |
| goto restart; |
| } |
| } |
| } |
| |
| /** |
| * cgroup_save_control - save control masks of a subtree |
| * @cgrp: root of the target subtree |
| * |
| * Save ->subtree_control and ->subtree_ss_mask to the respective old_ |
| * prefixed fields for @cgrp's subtree including @cgrp itself. |
| */ |
| static void cgroup_save_control(struct cgroup *cgrp) |
| { |
| struct cgroup *dsct; |
| struct cgroup_subsys_state *d_css; |
| |
| cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) { |
| dsct->old_subtree_control = dsct->subtree_control; |
| dsct->old_subtree_ss_mask = dsct->subtree_ss_mask; |
| } |
| } |
| |
| /** |
| * cgroup_propagate_control - refresh control masks of a subtree |
| * @cgrp: root of the target subtree |
| * |
| * For @cgrp and its subtree, ensure ->subtree_ss_mask matches |
| * ->subtree_control and propagate controller availability through the |
| * subtree so that descendants don't have unavailable controllers enabled. |
| */ |
| static void cgroup_propagate_control(struct cgroup *cgrp) |
| { |
| struct cgroup *dsct; |
| struct cgroup_subsys_state *d_css; |
| |
| cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) { |
| dsct->subtree_control &= cgroup_control(dsct); |
| dsct->subtree_ss_mask = |
| cgroup_calc_subtree_ss_mask(dsct->subtree_control, |
| cgroup_ss_mask(dsct)); |
| } |
| } |
| |
| /** |
| * cgroup_restore_control - restore control masks of a subtree |
| * @cgrp: root of the target subtree |
| * |
| * Restore ->subtree_control and ->subtree_ss_mask from the respective old_ |
| * prefixed fields for @cgrp's subtree including @cgrp itself. |
| */ |
| static void cgroup_restore_control(struct cgroup *cgrp) |
| { |
| struct cgroup *dsct; |
| struct cgroup_subsys_state *d_css; |
| |
| cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) { |
| dsct->subtree_control = dsct->old_subtree_control; |
| dsct->subtree_ss_mask = dsct->old_subtree_ss_mask; |
| } |
| } |
| |
| static bool css_visible(struct cgroup_subsys_state *css) |
| { |
| struct cgroup_subsys *ss = css->ss; |
| struct cgroup *cgrp = css->cgroup; |
| |
| if (cgroup_control(cgrp) & (1 << ss->id)) |
| return true; |
| if (!(cgroup_ss_mask(cgrp) & (1 << ss->id))) |
| return false; |
| return cgroup_on_dfl(cgrp) && ss->implicit_on_dfl; |
| } |
| |
| /** |
| * cgroup_apply_control_enable - enable or show csses according to control |
| * @cgrp: root of the target subtree |
| * |
| * Walk @cgrp's subtree and create new csses or make the existing ones |
| * visible. A css is created invisible if it's being implicitly enabled |
| * through dependency. An invisible css is made visible when the userland |
| * explicitly enables it. |
| * |
| * Returns 0 on success, -errno on failure. On failure, csses which have |
| * been processed already aren't cleaned up. The caller is responsible for |
| * cleaning up with cgroup_apply_control_disble(). |
| */ |
| static int cgroup_apply_control_enable(struct cgroup *cgrp) |
| { |
| struct cgroup *dsct; |
| struct cgroup_subsys_state *d_css; |
| struct cgroup_subsys *ss; |
| int ssid, ret; |
| |
| cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) { |
| for_each_subsys(ss, ssid) { |
| struct cgroup_subsys_state *css = cgroup_css(dsct, ss); |
| |
| WARN_ON_ONCE(css && percpu_ref_is_dying(&css->refcnt)); |
| |
| if (!(cgroup_ss_mask(dsct) & (1 << ss->id))) |
| continue; |
| |
| if (!css) { |
| css = css_create(dsct, ss); |
| if (IS_ERR(css)) |
| return PTR_ERR(css); |
| } |
| |
| if (css_visible(css)) { |
| ret = css_populate_dir(css); |
| if (ret) |
| return ret; |
| } |
| } |
| } |
| |
| return 0; |
| } |
| |
| /** |
| * cgroup_apply_control_disable - kill or hide csses according to control |
| * @cgrp: root of the target subtree |
| * |
| * Walk @cgrp's subtree and kill and hide csses so that they match |
| * cgroup_ss_mask() and cgroup_visible_mask(). |
| * |
| * A css is hidden when the userland requests it to be disabled while other |
| * subsystems are still depending on it. The css must not actively control |
| * resources and be in the vanilla state if it's made visible again later. |
| * Controllers which may be depended upon should provide ->css_reset() for |
| * this purpose. |
| */ |
| static void cgroup_apply_control_disable(struct cgroup *cgrp) |
| { |
| struct cgroup *dsct; |
| struct cgroup_subsys_state *d_css; |
| struct cgroup_subsys *ss; |
| int ssid; |
| |
| cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) { |
| for_each_subsys(ss, ssid) { |
| struct cgroup_subsys_state *css = cgroup_css(dsct, ss); |
| |
| WARN_ON_ONCE(css && percpu_ref_is_dying(&css->refcnt)); |
| |
| if (!css) |
| continue; |
| |
| if (css->parent && |
| !(cgroup_ss_mask(dsct) & (1 << ss->id))) { |
| kill_css(css); |
| } else if (!css_visible(css)) { |
| css_clear_dir(css); |
| if (ss->css_reset) |
| ss->css_reset(css); |
| } |
| } |
| } |
| } |
| |
| /** |
| * cgroup_apply_control - apply control mask updates to the subtree |
| * @cgrp: root of the target subtree |
| * |
| * subsystems can be enabled and disabled in a subtree using the following |
| * steps. |
| * |
| * 1. Call cgroup_save_control() to stash the current state. |
| * 2. Update ->subtree_control masks in the subtree as desired. |
| * 3. Call cgroup_apply_control() to apply the changes. |
| * 4. Optionally perform other related operations. |
| * 5. Call cgroup_finalize_control() to finish up. |
| * |
| * This function implements step 3 and propagates the mask changes |
| * throughout @cgrp's subtree, updates csses accordingly and perform |
| * process migrations. |
| */ |
| static int cgroup_apply_control(struct cgroup *cgrp) |
| { |
| int ret; |
| |
| cgroup_propagate_control(cgrp); |
| |
| ret = cgroup_apply_control_enable(cgrp); |
| if (ret) |
| return ret; |
| |
| /* |
| * At this point, cgroup_e_css() results reflect the new csses |
| * making the following cgroup_update_dfl_csses() properly update |
| * css associations of all tasks in the subtree. |
| */ |
| ret = cgroup_update_dfl_csses(cgrp); |
| if (ret) |
| return ret; |
| |
| return 0; |
| } |
| |
| /** |
| * cgroup_finalize_control - finalize control mask update |
| * @cgrp: root of the target subtree |
| * @ret: the result of the update |
| * |
| * Finalize control mask update. See cgroup_apply_control() for more info. |
| */ |
| static void cgroup_finalize_control(struct cgroup *cgrp, int ret) |
| { |
| if (ret) { |
| cgroup_restore_control(cgrp); |
| cgroup_propagate_control(cgrp); |
| } |
| |
| cgroup_apply_control_disable(cgrp); |
| } |
| |
| /* change the enabled child controllers for a cgroup in the default hierarchy */ |
| static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, |
| char *buf, size_t nbytes, |
| loff_t off) |
| { |
| u16 enable = 0, disable = 0; |
| struct cgroup *cgrp, *child; |
| struct cgroup_subsys *ss; |
| char *tok; |
| int ssid, ret; |
| |
| /* |
| * Parse input - space separated list of subsystem names prefixed |
| * with either + or -. |
| */ |
| buf = strstrip(buf); |
| while ((tok = strsep(&buf, " "))) { |
| if (tok[0] == '\0') |
| continue; |
| do_each_subsys_mask(ss, ssid, ~cgrp_dfl_inhibit_ss_mask) { |
| if (!cgroup_ssid_enabled(ssid) || |
| strcmp(tok + 1, ss->name)) |
| continue; |
| |
| if (*tok == '+') { |
| enable |= 1 << ssid; |
| disable &= ~(1 << ssid); |
| } else if (*tok == '-') { |
| disable |= 1 << ssid; |
| enable &= ~(1 << ssid); |
| } else { |
| return -EINVAL; |
| } |
| break; |
| } while_each_subsys_mask(); |
| if (ssid == CGROUP_SUBSYS_COUNT) |
| return -EINVAL; |
| } |
| |
| cgrp = cgroup_kn_lock_live(of->kn, true); |
| if (!cgrp) |
| return -ENODEV; |
| |
| for_each_subsys(ss, ssid) { |
| if (enable & (1 << ssid)) { |
| if (cgrp->subtree_control & (1 << ssid)) { |
| enable &= ~(1 << ssid); |
| continue; |
| } |
| |
| if (!(cgroup_control(cgrp) & (1 << ssid))) { |
| ret = -ENOENT; |
| goto out_unlock; |
| } |
| } else if (disable & (1 << ssid)) { |
| if (!(cgrp->subtree_control & (1 << ssid))) { |
| disable &= ~(1 << ssid); |
| continue; |
| } |
| |
| /* a child has it enabled? */ |
| cgroup_for_each_live_child(child, cgrp) { |
| if (child->subtree_control & (1 << ssid)) { |
| ret = -EBUSY; |
| goto out_unlock; |
| } |
| } |
| } |
| } |
| |
| if (!enable && !disable) { |
| ret = 0; |
| goto out_unlock; |
| } |
| |
| /* |
| * Except for the root, subtree_control must be zero for a cgroup |
| * with tasks so that child cgroups don't compete against tasks. |
| */ |
| if (enable && cgroup_parent(cgrp)) { |
| struct cgrp_cset_link *link; |
| |
| /* |
| * Because namespaces pin csets too, @cgrp->cset_links |
| * might not be empty even when @cgrp is empty. Walk and |
| * verify each cset. |
| */ |
| spin_lock_irq(&css_set_lock); |
| |
| ret = 0; |
| list_for_each_entry(link, &cgrp->cset_links, cset_link) { |
| if (css_set_populated(link->cset)) { |
| ret = -EBUSY; |
| break; |
| } |
| } |
| |
| spin_unlock_irq(&css_set_lock); |
| |
| if (ret) |
| goto out_unlock; |
| } |
| |
| /* save and update control masks and prepare csses */ |
| cgroup_save_control(cgrp); |
| |
| cgrp->subtree_control |= enable; |
| cgrp->subtree_control &= ~disable; |
| |
| ret = cgroup_apply_control(cgrp); |
| |
| cgroup_finalize_control(cgrp, ret); |
| |
| kernfs_activate(cgrp->kn); |
| ret = 0; |
| out_unlock: |
| cgroup_kn_unlock(of->kn); |
| return ret ?: nbytes; |
| } |
| |
| static int cgroup_events_show(struct seq_file *seq, void *v) |
| { |
| seq_printf(seq, "populated %d\n", |
| cgroup_is_populated(seq_css(seq)->cgroup)); |
| return 0; |
| } |
| |
| static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf, |
| size_t nbytes, loff_t off) |
| { |
| struct cgroup *cgrp = of->kn->parent->priv; |
| struct cftype *cft = of->kn->priv; |
| struct cgroup_subsys_state *css; |
| int ret; |
| |
| if (cft->write) |
| return cft->write(of, buf, nbytes, off); |
| |
| /* |
| * kernfs guarantees that a file isn't deleted with operations in |
| * flight, which means that the matching css is and stays alive and |
| * doesn't need to be pinned. The RCU locking is not necessary |
| * either. It's just for the convenience of using cgroup_css(). |
| */ |
| rcu_read_lock(); |
| css = cgroup_css(cgrp, cft->ss); |
| rcu_read_unlock(); |
| |
| if (cft->write_u64) { |
| unsigned long long v; |
| ret = kstrtoull(buf, 0, &v); |
| if (!ret) |
| ret = cft->write_u64(css, cft, v); |
| } else if (cft->write_s64) { |
| long long v; |
| ret = kstrtoll(buf, 0, &v); |
| if (!ret) |
| ret = cft->write_s64(css, cft, v); |
| } else { |
| ret = -EINVAL; |
| } |
| |
| return ret ?: nbytes; |
| } |
| |
| static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos) |
| { |
| return seq_cft(seq)->seq_start(seq, ppos); |
| } |
| |
| static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos) |
| { |
| return seq_cft(seq)->seq_next(seq, v, ppos); |
| } |
| |
| static void cgroup_seqfile_stop(struct seq_file *seq, void *v) |
| { |
| seq_cft(seq)->seq_stop(seq, v); |
| } |
| |
| static int cgroup_seqfile_show(struct seq_file *m, void *arg) |
| { |
| struct cftype *cft = seq_cft(m); |
| struct cgroup_subsys_state *css = seq_css(m); |
| |
| if (cft->seq_show) |
| return cft->seq_show(m, arg); |
| |
| if (cft->read_u64) |
| seq_printf(m, "%llu\n", cft->read_u64(css, cft)); |
| else if (cft->read_s64) |
| seq_printf(m, "%lld\n", cft->read_s64(css, cft)); |
| else |
| return -EINVAL; |
| return 0; |
| } |
| |
| static struct kernfs_ops cgroup_kf_single_ops = { |
| .atomic_write_len = PAGE_SIZE, |
| .write = cgroup_file_write, |
| .seq_show = cgroup_seqfile_show, |
| }; |
| |
| static struct kernfs_ops cgroup_kf_ops = { |
| .atomic_write_len = PAGE_SIZE, |
| .write = cgroup_file_write, |
| .seq_start = cgroup_seqfile_start, |
| .seq_next = cgroup_seqfile_next, |
| .seq_stop = cgroup_seqfile_stop, |
| .seq_show = cgroup_seqfile_show, |
| }; |
| |
| /* |
| * cgroup_rename - Only allow simple rename of directories in place. |
| */ |
| static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent, |
| const char *new_name_str) |
| { |
| struct cgroup *cgrp = kn->priv; |
| int ret; |
| |
| if (kernfs_type(kn) != KERNFS_DIR) |
| return -ENOTDIR; |
| if (kn->parent != new_parent) |
| return -EIO; |
| |
| /* |
| * This isn't a proper migration and its usefulness is very |
| * limited. Disallow on the default hierarchy. |
| */ |
| if (cgroup_on_dfl(cgrp)) |
| return -EPERM; |
| |
| /* |
| * We're gonna grab cgroup_mutex which nests outside kernfs |
| * active_ref. kernfs_rename() doesn't require active_ref |
| * protection. Break them before grabbing cgroup_mutex. |
| */ |
| kernfs_break_active_protection(new_parent); |
| kernfs_break_active_protection(kn); |
| |
| mutex_lock(&cgroup_mutex); |
| |
| ret = kernfs_rename(kn, new_parent, new_name_str); |
| |
| mutex_unlock(&cgroup_mutex); |
| |
| kernfs_unbreak_active_protection(kn); |
| kernfs_unbreak_active_protection(new_parent); |
| return ret; |
| } |
| |
| /* set uid and gid of cgroup dirs and files to that of the creator */ |
| static int cgroup_kn_set_ugid(struct kernfs_node *kn) |
| { |
| struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID, |
| .ia_uid = current_fsuid(), |
| .ia_gid = current_fsgid(), }; |
| |
| if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) && |
| gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID)) |
| return 0; |
| |
| return kernfs_setattr(kn, &iattr); |
| } |
| |
| static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp, |
| struct cftype *cft) |
| { |
| char name[CGROUP_FILE_NAME_MAX]; |
| struct kernfs_node *kn; |
| struct lock_class_key *key = NULL; |
| int ret; |
| |
| #ifdef CONFIG_DEBUG_LOCK_ALLOC |
| key = &cft->lockdep_key; |
| #endif |
| kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name), |
| cgroup_file_mode(cft), 0, cft->kf_ops, cft, |
| NULL, key); |
| if (IS_ERR(kn)) |
| return PTR_ERR(kn); |
| |
| ret = cgroup_kn_set_ugid(kn); |
| if (ret) { |
| kernfs_remove(kn); |
| return ret; |
| } |
| |
| if (cft->file_offset) { |
| struct cgroup_file *cfile = (void *)css + cft->file_offset; |
| |
| spin_lock_irq(&cgroup_file_kn_lock); |
| cfile->kn = kn; |
| spin_unlock_irq(&cgroup_file_kn_lock); |
| } |
| |
| return 0; |
| } |
| |
| /** |
| * cgroup_addrm_files - add or remove files to a cgroup directory |
| * @css: the target css |
| * @cgrp: the target cgroup (usually css->cgroup) |
| * @cfts: array of cftypes to be added |
| * @is_add: whether to add or remove |
| * |
| * Depending on @is_add, add or remove files defined by @cfts on @cgrp. |
| * For removals, this function never fails. |
| */ |
| static int cgroup_addrm_files(struct cgroup_subsys_state *css, |
| struct cgroup *cgrp, struct cftype cfts[], |
| bool is_add) |
| { |
| struct cftype *cft, *cft_end = NULL; |
| int ret = 0; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| restart: |
| for (cft = cfts; cft != cft_end && cft->name[0] != '\0'; cft++) { |
| /* does cft->flags tell us to skip this file on @cgrp? */ |
| if ((cft->flags & __CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp)) |
| continue; |
| if ((cft->flags & __CFTYPE_NOT_ON_DFL) && cgroup_on_dfl(cgrp)) |
| continue; |
| if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgroup_parent(cgrp)) |
| continue; |
| if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgroup_parent(cgrp)) |
| continue; |
| |
| if (is_add) { |
| ret = cgroup_add_file(css, cgrp, cft); |
| if (ret) { |
| pr_warn("%s: failed to add %s, err=%d\n", |
| __func__, cft->name, ret); |
| cft_end = cft; |
| is_add = false; |
| goto restart; |
| } |
| } else { |
| cgroup_rm_file(cgrp, cft); |
| } |
| } |
| return ret; |
| } |
| |
| static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add) |
| { |
| LIST_HEAD(pending); |
| struct cgroup_subsys *ss = cfts[0].ss; |
| struct cgroup *root = &ss->root->cgrp; |
| struct cgroup_subsys_state *css; |
| int ret = 0; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| /* add/rm files for all cgroups created before */ |
| css_for_each_descendant_pre(css, cgroup_css(root, ss)) { |
| struct cgroup *cgrp = css->cgroup; |
| |
| if (!(css->flags & CSS_VISIBLE)) |
| continue; |
| |
| ret = cgroup_addrm_files(css, cgrp, cfts, is_add); |
| if (ret) |
| break; |
| } |
| |
| if (is_add && !ret) |
| kernfs_activate(root->kn); |
| return ret; |
| } |
| |
| static void cgroup_exit_cftypes(struct cftype *cfts) |
| { |
| struct cftype *cft; |
| |
| for (cft = cfts; cft->name[0] != '\0'; cft++) { |
| /* free copy for custom atomic_write_len, see init_cftypes() */ |
| if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) |
| kfree(cft->kf_ops); |
| cft->kf_ops = NULL; |
| cft->ss = NULL; |
| |
| /* revert flags set by cgroup core while adding @cfts */ |
| cft->flags &= ~(__CFTYPE_ONLY_ON_DFL | __CFTYPE_NOT_ON_DFL); |
| } |
| } |
| |
| static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
| { |
| struct cftype *cft; |
| |
| for (cft = cfts; cft->name[0] != '\0'; cft++) { |
| struct kernfs_ops *kf_ops; |
| |
| WARN_ON(cft->ss || cft->kf_ops); |
| |
| if (cft->seq_start) |
| kf_ops = &cgroup_kf_ops; |
| else |
| kf_ops = &cgroup_kf_single_ops; |
| |
| /* |
| * Ugh... if @cft wants a custom max_write_len, we need to |
| * make a copy of kf_ops to set its atomic_write_len. |
| */ |
| if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) { |
| kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL); |
| if (!kf_ops) { |
| cgroup_exit_cftypes(cfts); |
| return -ENOMEM; |
| } |
| kf_ops->atomic_write_len = cft->max_write_len; |
| } |
| |
| cft->kf_ops = kf_ops; |
| cft->ss = ss; |
| } |
| |
| return 0; |
| } |
| |
| static int cgroup_rm_cftypes_locked(struct cftype *cfts) |
| { |
| lockdep_assert_held(&cgroup_mutex); |
| |
| if (!cfts || !cfts[0].ss) |
| return -ENOENT; |
| |
| list_del(&cfts->node); |
| cgroup_apply_cftypes(cfts, false); |
| cgroup_exit_cftypes(cfts); |
| return 0; |
| } |
| |
| /** |
| * cgroup_rm_cftypes - remove an array of cftypes from a subsystem |
| * @cfts: zero-length name terminated array of cftypes |
| * |
| * Unregister @cfts. Files described by @cfts are removed from all |
| * existing cgroups and all future cgroups won't have them either. This |
| * function can be called anytime whether @cfts' subsys is attached or not. |
| * |
| * Returns 0 on successful unregistration, -ENOENT if @cfts is not |
| * registered. |
| */ |
| int cgroup_rm_cftypes(struct cftype *cfts) |
| { |
| int ret; |
| |
| mutex_lock(&cgroup_mutex); |
| ret = cgroup_rm_cftypes_locked(cfts); |
| mutex_unlock(&cgroup_mutex); |
| return ret; |
| } |
| |
| /** |
| * cgroup_add_cftypes - add an array of cftypes to a subsystem |
| * @ss: target cgroup subsystem |
| * @cfts: zero-length name terminated array of cftypes |
| * |
| * Register @cfts to @ss. Files described by @cfts are created for all |
| * existing cgroups to which @ss is attached and all future cgroups will |
| * have them too. This function can be called anytime whether @ss is |
| * attached or not. |
| * |
| * Returns 0 on successful registration, -errno on failure. Note that this |
| * function currently returns 0 as long as @cfts registration is successful |
| * even if some file creation attempts on existing cgroups fail. |
| */ |
| static int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
| { |
| int ret; |
| |
| if (!cgroup_ssid_enabled(ss->id)) |
| return 0; |
| |
| if (!cfts || cfts[0].name[0] == '\0') |
| return 0; |
| |
| ret = cgroup_init_cftypes(ss, cfts); |
| if (ret) |
| return ret; |
| |
| mutex_lock(&cgroup_mutex); |
| |
| list_add_tail(&cfts->node, &ss->cfts); |
| ret = cgroup_apply_cftypes(cfts, true); |
| if (ret) |
| cgroup_rm_cftypes_locked(cfts); |
| |
| mutex_unlock(&cgroup_mutex); |
| return ret; |
| } |
| |
| /** |
| * cgroup_add_dfl_cftypes - add an array of cftypes for default hierarchy |
| * @ss: target cgroup subsystem |
| * @cfts: zero-length name terminated array of cftypes |
| * |
| * Similar to cgroup_add_cftypes() but the added files are only used for |
| * the default hierarchy. |
| */ |
| int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
| { |
| struct cftype *cft; |
| |
| for (cft = cfts; cft && cft->name[0] != '\0'; cft++) |
| cft->flags |= __CFTYPE_ONLY_ON_DFL; |
| return cgroup_add_cftypes(ss, cfts); |
| } |
| |
| /** |
| * cgroup_add_legacy_cftypes - add an array of cftypes for legacy hierarchies |
| * @ss: target cgroup subsystem |
| * @cfts: zero-length name terminated array of cftypes |
| * |
| * Similar to cgroup_add_cftypes() but the added files are only used for |
| * the legacy hierarchies. |
| */ |
| int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
| { |
| struct cftype *cft; |
| |
| for (cft = cfts; cft && cft->name[0] != '\0'; cft++) |
| cft->flags |= __CFTYPE_NOT_ON_DFL; |
| return cgroup_add_cftypes(ss, cfts); |
| } |
| |
| /** |
| * cgroup_file_notify - generate a file modified event for a cgroup_file |
| * @cfile: target cgroup_file |
| * |
| * @cfile must have been obtained by setting cftype->file_offset. |
| */ |
| void cgroup_file_notify(struct cgroup_file *cfile) |
| { |
| unsigned long flags; |
| |
| spin_lock_irqsave(&cgroup_file_kn_lock, flags); |
| if (cfile->kn) |
| kernfs_notify(cfile->kn); |
| spin_unlock_irqrestore(&cgroup_file_kn_lock, flags); |
| } |
| |
| /** |
| * cgroup_task_count - count the number of tasks in a cgroup. |
| * @cgrp: the cgroup in question |
| * |
| * Return the number of tasks in the cgroup. The returned number can be |
| * higher than the actual number of tasks due to css_set references from |
| * namespace roots and temporary usages. |
| */ |
| static int cgroup_task_count(const struct cgroup *cgrp) |
| { |
| int count = 0; |
| struct cgrp_cset_link *link; |
| |
| spin_lock_irq(&css_set_lock); |
| list_for_each_entry(link, &cgrp->cset_links, cset_link) |
| count += atomic_read(&link->cset->refcount); |
| spin_unlock_irq(&css_set_lock); |
| return count; |
| } |
| |
| /** |
| * css_next_child - find the next child of a given css |
| * @pos: the current position (%NULL to initiate traversal) |
| * @parent: css whose children to walk |
| * |
| * This function returns the next child of @parent and should be called |
| * under either cgroup_mutex or RCU read lock. The only requirement is |
| * that @parent and @pos are accessible. The next sibling is guaranteed to |
| * be returned regardless of their states. |
| * |
| * If a subsystem synchronizes ->css_online() and the start of iteration, a |
| * css which finished ->css_online() is guaranteed to be visible in the |
| * future iterations and will stay visible until the last reference is put. |
| * A css which hasn't finished ->css_online() or already finished |
| * ->css_offline() may show up during traversal. It's each subsystem's |
| * responsibility to synchronize against on/offlining. |
| */ |
| struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos, |
| struct cgroup_subsys_state *parent) |
| { |
| struct cgroup_subsys_state *next; |
| |
| cgroup_assert_mutex_or_rcu_locked(); |
| |
| /* |
| * @pos could already have been unlinked from the sibling list. |
| * Once a cgroup is removed, its ->sibling.next is no longer |
| * updated when its next sibling changes. CSS_RELEASED is set when |
| * @pos is taken off list, at which time its next pointer is valid, |
| * and, as releases are serialized, the one pointed to by the next |
| * pointer is guaranteed to not have started release yet. This |
| * implies that if we observe !CSS_RELEASED on @pos in this RCU |
| * critical section, the one pointed to by its next pointer is |
| * guaranteed to not have finished its RCU grace period even if we |
| * have dropped rcu_read_lock() inbetween iterations. |
| * |
| * If @pos has CSS_RELEASED set, its next pointer can't be |
| * dereferenced; however, as each css is given a monotonically |
| * increasing unique serial number and always appended to the |
| * sibling list, the next one can be found by walking the parent's |
| * children until the first css with higher serial number than |
| * @pos's. While this path can be slower, it happens iff iteration |
| * races against release and the race window is very small. |
| */ |
| if (!pos) { |
| next = list_entry_rcu(parent->children.next, struct cgroup_subsys_state, sibling); |
| } else if (likely(!(pos->flags & CSS_RELEASED))) { |
| next = list_entry_rcu(pos->sibling.next, struct cgroup_subsys_state, sibling); |
| } else { |
| list_for_each_entry_rcu(next, &parent->children, sibling) |
| if (next->serial_nr > pos->serial_nr) |
| break; |
| } |
| |
| /* |
| * @next, if not pointing to the head, can be dereferenced and is |
| * the next sibling. |
| */ |
| if (&next->sibling != &parent->children) |
| return next; |
| return NULL; |
| } |
| |
| /** |
| * css_next_descendant_pre - find the next descendant for pre-order walk |
| * @pos: the current position (%NULL to initiate traversal) |
| * @root: css whose descendants to walk |
| * |
| * To be used by css_for_each_descendant_pre(). Find the next descendant |
| * to visit for pre-order traversal of @root's descendants. @root is |
| * included in the iteration and the first node to be visited. |
| * |
| * While this function requires cgroup_mutex or RCU read locking, it |
| * doesn't require the whole traversal to be contained in a single critical |
| * section. This function will return the correct next descendant as long |
| * as both @pos and @root are accessible and @pos is a descendant of @root. |
| * |
| * If a subsystem synchronizes ->css_online() and the start of iteration, a |
| * css which finished ->css_online() is guaranteed to be visible in the |
| * future iterations and will stay visible until the last reference is put. |
| * A css which hasn't finished ->css_online() or already finished |
| * ->css_offline() may show up during traversal. It's each subsystem's |
| * responsibility to synchronize against on/offlining. |
| */ |
| struct cgroup_subsys_state * |
| css_next_descendant_pre(struct cgroup_subsys_state *pos, |
| struct cgroup_subsys_state *root) |
| { |
| struct cgroup_subsys_state *next; |
| |
| cgroup_assert_mutex_or_rcu_locked(); |
| |
| /* if first iteration, visit @root */ |
| if (!pos) |
| return root; |
| |
| /* visit the first child if exists */ |
| next = css_next_child(NULL, pos); |
| if (next) |
| return next; |
| |
| /* no child, visit my or the closest ancestor's next sibling */ |
| while (pos != root) { |
| next = css_next_child(pos, pos->parent); |
| if (next) |
| return next; |
| pos = pos->parent; |
| } |
| |
| return NULL; |
| } |
| |
| /** |
| * css_rightmost_descendant - return the rightmost descendant of a css |
| * @pos: css of interest |
| * |
| * Return the rightmost descendant of @pos. If there's no descendant, @pos |
| * is returned. This can be used during pre-order traversal to skip |
| * subtree of @pos. |
| * |
| * While this function requires cgroup_mutex or RCU read locking, it |
| * doesn't require the whole traversal to be contained in a single critical |
| * section. This function will return the correct rightmost descendant as |
| * long as @pos is accessible. |
| */ |
| struct cgroup_subsys_state * |
| css_rightmost_descendant(struct cgroup_subsys_state *pos) |
| { |
| struct cgroup_subsys_state *last, *tmp; |
| |
| cgroup_assert_mutex_or_rcu_locked(); |
| |
| do { |
| last = pos; |
| /* ->prev isn't RCU safe, walk ->next till the end */ |
| pos = NULL; |
| css_for_each_child(tmp, last) |
| pos = tmp; |
| } while (pos); |
| |
| return last; |
| } |
| |
| static struct cgroup_subsys_state * |
| css_leftmost_descendant(struct cgroup_subsys_state *pos) |
| { |
| struct cgroup_subsys_state *last; |
| |
| do { |
| last = pos; |
| pos = css_next_child(NULL, pos); |
| } while (pos); |
| |
| return last; |
| } |
| |
| /** |
| * css_next_descendant_post - find the next descendant for post-order walk |
| * @pos: the current position (%NULL to initiate traversal) |
| * @root: css whose descendants to walk |
| * |
| * To be used by css_for_each_descendant_post(). Find the next descendant |
| * to visit for post-order traversal of @root's descendants. @root is |
| * included in the iteration and the last node to be visited. |
| * |
| * While this function requires cgroup_mutex or RCU read locking, it |
| * doesn't require the whole traversal to be contained in a single critical |
| * section. This function will return the correct next descendant as long |
| * as both @pos and @cgroup are accessible and @pos is a descendant of |
| * @cgroup. |
| * |
| * If a subsystem synchronizes ->css_online() and the start of iteration, a |
| * css which finished ->css_online() is guaranteed to be visible in the |
| * future iterations and will stay visible until the last reference is put. |
| * A css which hasn't finished ->css_online() or already finished |
| * ->css_offline() may show up during traversal. It's each subsystem's |
| * responsibility to synchronize against on/offlining. |
| */ |
| struct cgroup_subsys_state * |
| css_next_descendant_post(struct cgroup_subsys_state *pos, |
| struct cgroup_subsys_state *root) |
| { |
| struct cgroup_subsys_state *next; |
| |
| cgroup_assert_mutex_or_rcu_locked(); |
| |
| /* if first iteration, visit leftmost descendant which may be @root */ |
| if (!pos) |
| return css_leftmost_descendant(root); |
| |
| /* if we visited @root, we're done */ |
| if (pos == root) |
| return NULL; |
| |
| /* if there's an unvisited sibling, visit its leftmost descendant */ |
| next = css_next_child(pos, pos->parent); |
| if (next) |
| return css_leftmost_descendant(next); |
| |
| /* no sibling left, visit parent */ |
| return pos->parent; |
| } |
| |
| /** |
| * css_has_online_children - does a css have online children |
| * @css: the target css |
| * |
| * Returns %true if @css has any online children; otherwise, %false. This |
| * function can be called from any context but the caller is responsible |
| * for synchronizing against on/offlining as necessary. |
| */ |
| bool css_has_online_children(struct cgroup_subsys_state *css) |
| { |
| struct cgroup_subsys_state *child; |
| bool ret = false; |
| |
| rcu_read_lock(); |
| css_for_each_child(child, css) { |
| if (child->flags & CSS_ONLINE) { |
| ret = true; |
| break; |
| } |
| } |
| rcu_read_unlock(); |
| return ret; |
| } |
| |
| /** |
| * css_task_iter_advance_css_set - advance a task itererator to the next css_set |
| * @it: the iterator to advance |
| * |
| * Advance @it to the next css_set to walk. |
| */ |
| static void css_task_iter_advance_css_set(struct css_task_iter *it) |
| { |
| struct list_head *l = it->cset_pos; |
| struct cgrp_cset_link *link; |
| struct css_set *cset; |
| |
| lockdep_assert_held(&css_set_lock); |
| |
| /* Advance to the next non-empty css_set */ |
| do { |
| l = l->next; |
| if (l == it->cset_head) { |
| it->cset_pos = NULL; |
| it->task_pos = NULL; |
| return; |
| } |
| |
| if (it->ss) { |
| cset = container_of(l, struct css_set, |
| e_cset_node[it->ss->id]); |
| } else { |
| link = list_entry(l, struct cgrp_cset_link, cset_link); |
| cset = link->cset; |
| } |
| } while (!css_set_populated(cset)); |
| |
| it->cset_pos = l; |
| |
| if (!list_empty(&cset->tasks)) |
| it->task_pos = cset->tasks.next; |
| else |
| it->task_pos = cset->mg_tasks.next; |
| |
| it->tasks_head = &cset->tasks; |
| it->mg_tasks_head = &cset->mg_tasks; |
| |
| /* |
| * We don't keep css_sets locked across iteration steps and thus |
| * need to take steps to ensure that iteration can be resumed after |
| * the lock is re-acquired. Iteration is performed at two levels - |
| * css_sets and tasks in them. |
| * |
| * Once created, a css_set never leaves its cgroup lists, so a |
| * pinned css_set is guaranteed to stay put and we can resume |
| * iteration afterwards. |
| * |
| * Tasks may leave @cset across iteration steps. This is resolved |
| * by registering each iterator with the css_set currently being |
| * walked and making css_set_move_task() advance iterators whose |
| * next task is leaving. |
| */ |
| if (it->cur_cset) { |
| list_del(&it->iters_node); |
| put_css_set_locked(it->cur_cset); |
| } |
| get_css_set(cset); |
| it->cur_cset = cset; |
| list_add(&it->iters_node, &cset->task_iters); |
| } |
| |
| static void css_task_iter_advance(struct css_task_iter *it) |
| { |
| struct list_head *l = it->task_pos; |
| |
| lockdep_assert_held(&css_set_lock); |
| WARN_ON_ONCE(!l); |
| |
| /* |
| * Advance iterator to find next entry. cset->tasks is consumed |
| * first and then ->mg_tasks. After ->mg_tasks, we move onto the |
| * next cset. |
| */ |
| l = l->next; |
| |
| if (l == it->tasks_head) |
| l = it->mg_tasks_head->next; |
| |
| if (l == it->mg_tasks_head) |
| css_task_iter_advance_css_set(it); |
| else |
| it->task_pos = l; |
| } |
| |
| /** |
| * css_task_iter_start - initiate task iteration |
| * @css: the css to walk tasks of |
| * @it: the task iterator to use |
| * |
| * Initiate iteration through the tasks of @css. The caller can call |
| * css_task_iter_next() to walk through the tasks until the function |
| * returns NULL. On completion of iteration, css_task_iter_end() must be |
| * called. |
| */ |
| void css_task_iter_start(struct cgroup_subsys_state *css, |
| struct css_task_iter *it) |
| { |
| /* no one should try to iterate before mounting cgroups */ |
| WARN_ON_ONCE(!use_task_css_set_links); |
| |
| memset(it, 0, sizeof(*it)); |
| |
| spin_lock_irq(&css_set_lock); |
| |
| it->ss = css->ss; |
| |
| if (it->ss) |
| it->cset_pos = &css->cgroup->e_csets[css->ss->id]; |
| else |
| it->cset_pos = &css->cgroup->cset_links; |
| |
| it->cset_head = it->cset_pos; |
| |
| css_task_iter_advance_css_set(it); |
| |
| spin_unlock_irq(&css_set_lock); |
| } |
| |
| /** |
| * css_task_iter_next - return the next task for the iterator |
| * @it: the task iterator being iterated |
| * |
| * The "next" function for task iteration. @it should have been |
| * initialized via css_task_iter_start(). Returns NULL when the iteration |
| * reaches the end. |
| */ |
| struct task_struct *css_task_iter_next(struct css_task_iter *it) |
| { |
| if (it->cur_task) { |
| put_task_struct(it->cur_task); |
| it->cur_task = NULL; |
| } |
| |
| spin_lock_irq(&css_set_lock); |
| |
| if (it->task_pos) { |
| it->cur_task = list_entry(it->task_pos, struct task_struct, |
| cg_list); |
| get_task_struct(it->cur_task); |
| css_task_iter_advance(it); |
| } |
| |
| spin_unlock_irq(&css_set_lock); |
| |
| return it->cur_task; |
| } |
| |
| /** |
| * css_task_iter_end - finish task iteration |
| * @it: the task iterator to finish |
| * |
| * Finish task iteration started by css_task_iter_start(). |
| */ |
| void css_task_iter_end(struct css_task_iter *it) |
| { |
| if (it->cur_cset) { |
| spin_lock_irq(&css_set_lock); |
| list_del(&it->iters_node); |
| put_css_set_locked(it->cur_cset); |
| spin_unlock_irq(&css_set_lock); |
| } |
| |
| if (it->cur_task) |
| put_task_struct(it->cur_task); |
| } |
| |
| /** |
| * cgroup_trasnsfer_tasks - move tasks from one cgroup to another |
| * @to: cgroup to which the tasks will be moved |
| * @from: cgroup in which the tasks currently reside |
| * |
| * Locking rules between cgroup_post_fork() and the migration path |
| * guarantee that, if a task is forking while being migrated, the new child |
| * is guaranteed to be either visible in the source cgroup after the |
| * parent's migration is complete or put into the target cgroup. No task |
| * can slip out of migration through forking. |
| */ |
| int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) |
| { |
| LIST_HEAD(preloaded_csets); |
| struct cgrp_cset_link *link; |
| struct css_task_iter it; |
| struct task_struct *task; |
| int ret; |
| |
| if (!cgroup_may_migrate_to(to)) |
| return -EBUSY; |
| |
| mutex_lock(&cgroup_mutex); |
| |
| percpu_down_write(&cgroup_threadgroup_rwsem); |
| |
| /* all tasks in @from are being moved, all csets are source */ |
| spin_lock_irq(&css_set_lock); |
| list_for_each_entry(link, &from->cset_links, cset_link) |
| cgroup_migrate_add_src(link->cset, to, &preloaded_csets); |
| spin_unlock_irq(&css_set_lock); |
| |
| ret = cgroup_migrate_prepare_dst(&preloaded_csets); |
| if (ret) |
| goto out_err; |
| |
| /* |
| * Migrate tasks one-by-one until @from is empty. This fails iff |
| * ->can_attach() fails. |
| */ |
| do { |
| css_task_iter_start(&from->self, &it); |
| task = css_task_iter_next(&it); |
| if (task) |
| get_task_struct(task); |
| css_task_iter_end(&it); |
| |
| if (task) { |
| ret = cgroup_migrate(task, false, to->root); |
| put_task_struct(task); |
| } |
| } while (task && !ret); |
| out_err: |
| cgroup_migrate_finish(&preloaded_csets); |
| percpu_up_write(&cgroup_threadgroup_rwsem); |
| mutex_unlock(&cgroup_mutex); |
| return ret; |
| } |
| |
| /* |
| * Stuff for reading the 'tasks'/'procs' files. |
| * |
| * Reading this file can return large amounts of data if a cgroup has |
| * *lots* of attached tasks. So it may need several calls to read(), |
| * but we cannot guarantee that the information we produce is correct |
| * unless we produce it entirely atomically. |
| * |
| */ |
| |
| /* which pidlist file are we talking about? */ |
| enum cgroup_filetype { |
| CGROUP_FILE_PROCS, |
| CGROUP_FILE_TASKS, |
| }; |
| |
| /* |
| * A pidlist is a list of pids that virtually represents the contents of one |
| * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists, |
| * a pair (one each for procs, tasks) for each pid namespace that's relevant |
| * to the cgroup. |
| */ |
| struct cgroup_pidlist { |
| /* |
| * used to find which pidlist is wanted. doesn't change as long as |
| * this particular list stays in the list. |
| */ |
| struct { enum cgroup_filetype type; struct pid_namespace *ns; } key; |
| /* array of xids */ |
| pid_t *list; |
| /* how many elements the above list has */ |
| int length; |
| /* each of these stored in a list by its cgroup */ |
| struct list_head links; |
| /* pointer to the cgroup we belong to, for list removal purposes */ |
| struct cgroup *owner; |
| /* for delayed destruction */ |
| struct delayed_work destroy_dwork; |
| }; |
| |
| /* |
| * The following two functions "fix" the issue where there are more pids |
| * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. |
| * TODO: replace with a kernel-wide solution to this problem |
| */ |
| #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2)) |
| static void *pidlist_allocate(int count) |
| { |
| if (PIDLIST_TOO_LARGE(count)) |
| return vmalloc(count * sizeof(pid_t)); |
| else |
| return kmalloc(count * sizeof(pid_t), GFP_KERNEL); |
| } |
| |
| static void pidlist_free(void *p) |
| { |
| kvfree(p); |
| } |
| |
| /* |
| * Used to destroy all pidlists lingering waiting for destroy timer. None |
| * should be left afterwards. |
| */ |
| static void cgroup_pidlist_destroy_all(struct cgroup *cgrp) |
| { |
| struct cgroup_pidlist *l, *tmp_l; |
| |
| mutex_lock(&cgrp->pidlist_mutex); |
| list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links) |
| mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0); |
| mutex_unlock(&cgrp->pidlist_mutex); |
| |
| flush_workqueue(cgroup_pidlist_destroy_wq); |
| BUG_ON(!list_empty(&cgrp->pidlists)); |
| } |
| |
| static void cgroup_pidlist_destroy_work_fn(struct work_struct *work) |
| { |
| struct delayed_work *dwork = to_delayed_work(work); |
| struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist, |
| destroy_dwork); |
| struct cgroup_pidlist *tofree = NULL; |
| |
| mutex_lock(&l->owner->pidlist_mutex); |
| |
| /* |
| * Destroy iff we didn't get queued again. The state won't change |
| * as destroy_dwork can only be queued while locked. |
| */ |
| if (!delayed_work_pending(dwork)) { |
| list_del(&l->links); |
| pidlist_free(l->list); |
| put_pid_ns(l->key.ns); |
| tofree = l; |
| } |
| |
| mutex_unlock(&l->owner->pidlist_mutex); |
| kfree(tofree); |
| } |
| |
| /* |
| * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries |
| * Returns the number of unique elements. |
| */ |
| static int pidlist_uniq(pid_t *list, int length) |
| { |
| int src, dest = 1; |
| |
| /* |
| * we presume the 0th element is unique, so i starts at 1. trivial |
| * edge cases first; no work needs to be done for either |
| */ |
| if (length == 0 || length == 1) |
| return length; |
| /* src and dest walk down the list; dest counts unique elements */ |
| for (src = 1; src < length; src++) { |
| /* find next unique element */ |
| while (list[src] == list[src-1]) { |
| src++; |
| if (src == length) |
| goto after; |
| } |
| /* dest always points to where the next unique element goes */ |
| list[dest] = list[src]; |
| dest++; |
| } |
| after: |
| return dest; |
| } |
| |
| /* |
| * The two pid files - task and cgroup.procs - guaranteed that the result |
| * is sorted, which forced this whole pidlist fiasco. As pid order is |
| * different per namespace, each namespace needs differently sorted list, |
| * making it impossible to use, for example, single rbtree of member tasks |
| * sorted by task pointer. As pidlists can be fairly large, allocating one |
| * per open file is dangerous, so cgroup had to implement shared pool of |
| * pidlists keyed by cgroup and namespace. |
| * |
| * All this extra complexity was caused by the original implementation |
| * committing to an entirely unnecessary property. In the long term, we |
| * want to do away with it. Explicitly scramble sort order if on the |
| * default hierarchy so that no such expectation exists in the new |
| * interface. |
| * |
| * Scrambling is done by swapping every two consecutive bits, which is |
| * non-identity one-to-one mapping which disturbs sort order sufficiently. |
| */ |
| static pid_t pid_fry(pid_t pid) |
| { |
| unsigned a = pid & 0x55555555; |
| unsigned b = pid & 0xAAAAAAAA; |
| |
| return (a << 1) | (b >> 1); |
| } |
| |
| static pid_t cgroup_pid_fry(struct cgroup *cgrp, pid_t pid) |
| { |
| if (cgroup_on_dfl(cgrp)) |
| return pid_fry(pid); |
| else |
| return pid; |
| } |
| |
| static int cmppid(const void *a, const void *b) |
| { |
| return *(pid_t *)a - *(pid_t *)b; |
| } |
| |
| static int fried_cmppid(const void *a, const void *b) |
| { |
| return pid_fry(*(pid_t *)a) - pid_fry(*(pid_t *)b); |
| } |
| |
| static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, |
| enum cgroup_filetype type) |
| { |
| struct cgroup_pidlist *l; |
| /* don't need task_nsproxy() if we're looking at ourself */ |
| struct pid_namespace *ns = task_active_pid_ns(current); |
| |
| lockdep_assert_held(&cgrp->pidlist_mutex); |
| |
| list_for_each_entry(l, &cgrp->pidlists, links) |
| if (l->key.type == type && l->key.ns == ns) |
| return l; |
| return NULL; |
| } |
| |
| /* |
| * find the appropriate pidlist for our purpose (given procs vs tasks) |
| * returns with the lock on that pidlist already held, and takes care |
| * of the use count, or returns NULL with no locks held if we're out of |
| * memory. |
| */ |
| static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp, |
| enum cgroup_filetype type) |
| { |
| struct cgroup_pidlist *l; |
| |
| lockdep_assert_held(&cgrp->pidlist_mutex); |
| |
| l = cgroup_pidlist_find(cgrp, type); |
| if (l) |
| return l; |
| |
| /* entry not found; create a new one */ |
| l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); |
| if (!l) |
| return l; |
| |
| INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn); |
| l->key.type = type; |
| /* don't need task_nsproxy() if we're looking at ourself */ |
| l->key.ns = get_pid_ns(task_active_pid_ns(current)); |
| l->owner = cgrp; |
| list_add(&l->links, &cgrp->pidlists); |
| return l; |
| } |
| |
| /* |
| * Load a cgroup's pidarray with either procs' tgids or tasks' pids |
| */ |
| static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, |
| struct cgroup_pidlist **lp) |
| { |
| pid_t *array; |
| int length; |
| int pid, n = 0; /* used for populating the array */ |
| struct css_task_iter it; |
| struct task_struct *tsk; |
| struct cgroup_pidlist *l; |
| |
| lockdep_assert_held(&cgrp->pidlist_mutex); |
| |
| /* |
| * If cgroup gets more users after we read count, we won't have |
| * enough space - tough. This race is indistinguishable to the |
| * caller from the case that the additional cgroup users didn't |
| * show up until sometime later on. |
| */ |
| length = cgroup_task_count(cgrp); |
| array = pidlist_allocate(length); |
| if (!array) |
| return -ENOMEM; |
| /* now, populate the array */ |
| css_task_iter_start(&cgrp->self, &it); |
| while ((tsk = css_task_iter_next(&it))) { |
| if (unlikely(n == length)) |
| break; |
| /* get tgid or pid for procs or tasks file respectively */ |
| if (type == CGROUP_FILE_PROCS) |
| pid = task_tgid_vnr(tsk); |
| else |
| pid = task_pid_vnr(tsk); |
| if (pid > 0) /* make sure to only use valid results */ |
| array[n++] = pid; |
| } |
| css_task_iter_end(&it); |
| length = n; |
| /* now sort & (if procs) strip out duplicates */ |
| if (cgroup_on_dfl(cgrp)) |
| sort(array, length, sizeof(pid_t), fried_cmppid, NULL); |
| else |
| sort(array, length, sizeof(pid_t), cmppid, NULL); |
| if (type == CGROUP_FILE_PROCS) |
| length = pidlist_uniq(array, length); |
| |
| l = cgroup_pidlist_find_create(cgrp, type); |
| if (!l) { |
| pidlist_free(array); |
| return -ENOMEM; |
| } |
| |
| /* store array, freeing old if necessary */ |
| pidlist_free(l->list); |
| l->list = array; |
| l->length = length; |
| *lp = l; |
| return 0; |
| } |
| |
| /** |
| * cgroupstats_build - build and fill cgroupstats |
| * @stats: cgroupstats to fill information into |
| * @dentry: A dentry entry belonging to the cgroup for which stats have |
| * been requested. |
| * |
| * Build and fill cgroupstats so that taskstats can export it to user |
| * space. |
| */ |
| int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) |
| { |
| struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
| struct cgroup *cgrp; |
| struct css_task_iter it; |
| struct task_struct *tsk; |
| |
| /* it should be kernfs_node belonging to cgroupfs and is a directory */ |
| if (dentry->d_sb->s_type != &cgroup_fs_type || !kn || |
| kernfs_type(kn) != KERNFS_DIR) |
| return -EINVAL; |
| |
| mutex_lock(&cgroup_mutex); |
| |
| /* |
| * We aren't being called from kernfs and there's no guarantee on |
| * @kn->priv's validity. For this and css_tryget_online_from_dir(), |
| * @kn->priv is RCU safe. Let's do the RCU dancing. |
| */ |
| rcu_read_lock(); |
| cgrp = rcu_dereference(kn->priv); |
| if (!cgrp || cgroup_is_dead(cgrp)) { |
| rcu_read_unlock(); |
| mutex_unlock(&cgroup_mutex); |
| return -ENOENT; |
| } |
| rcu_read_unlock(); |
| |
| css_task_iter_start(&cgrp->self, &it); |
| while ((tsk = css_task_iter_next(&it))) { |
| switch (tsk->state) { |
| case TASK_RUNNING: |
| stats->nr_running++; |
| break; |
| case TASK_INTERRUPTIBLE: |
| stats->nr_sleeping++; |
| break; |
| case TASK_UNINTERRUPTIBLE: |
| stats->nr_uninterruptible++; |
| break; |
| case TASK_STOPPED: |
| stats->nr_stopped++; |
| break; |
| default: |
| if (delayacct_is_task_waiting_on_io(tsk)) |
| stats->nr_io_wait++; |
| break; |
| } |
| } |
| css_task_iter_end(&it); |
| |
| mutex_unlock(&cgroup_mutex); |
| return 0; |
| } |
| |
| |
| /* |
| * seq_file methods for the tasks/procs files. The seq_file position is the |
| * next pid to display; the seq_file iterator is a pointer to the pid |
| * in the cgroup->l->list array. |
| */ |
| |
| static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) |
| { |
| /* |
| * Initially we receive a position value that corresponds to |
| * one more than the last pid shown (or 0 on the first call or |
| * after a seek to the start). Use a binary-search to find the |
| * next pid to display, if any |
| */ |
| struct kernfs_open_file *of = s->private; |
| struct cgroup *cgrp = seq_css(s)->cgroup; |
| struct cgroup_pidlist *l; |
| enum cgroup_filetype type = seq_cft(s)->private; |
| int index = 0, pid = *pos; |
| int *iter, ret; |
| |
| mutex_lock(&cgrp->pidlist_mutex); |
| |
| /* |
| * !NULL @of->priv indicates that this isn't the first start() |
| * after open. If the matching pidlist is around, we can use that. |
| * Look for it. Note that @of->priv can't be used directly. It |
| * could already have been destroyed. |
| */ |
| if (of->priv) |
| of->priv = cgroup_pidlist_find(cgrp, type); |
| |
| /* |
| * Either this is the first start() after open or the matching |
| * pidlist has been destroyed inbetween. Create a new one. |
| */ |
| if (!of->priv) { |
| ret = pidlist_array_load(cgrp, type, |
| (struct cgroup_pidlist **)&of->priv); |
| if (ret) |
| return ERR_PTR(ret); |
| } |
| l = of->priv; |
| |
| if (pid) { |
| int end = l->length; |
| |
| while (index < end) { |
| int mid = (index + end) / 2; |
| if (cgroup_pid_fry(cgrp, l->list[mid]) == pid) { |
| index = mid; |
| break; |
| } else if (cgroup_pid_fry(cgrp, l->list[mid]) <= pid) |
| index = mid + 1; |
| else |
| end = mid; |
| } |
| } |
| /* If we're off the end of the array, we're done */ |
| if (index >= l->length) |
| return NULL; |
| /* Update the abstract position to be the actual pid that we found */ |
| iter = l->list + index; |
| *pos = cgroup_pid_fry(cgrp, *iter); |
| return iter; |
| } |
| |
| static void cgroup_pidlist_stop(struct seq_file *s, void *v) |
| { |
| struct kernfs_open_file *of = s->private; |
| struct cgroup_pidlist *l = of->priv; |
| |
| if (l) |
| mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, |
| CGROUP_PIDLIST_DESTROY_DELAY); |
| mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex); |
| } |
| |
| static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) |
| { |
| struct kernfs_open_file *of = s->private; |
| struct cgroup_pidlist *l = of->priv; |
| pid_t *p = v; |
| pid_t *end = l->list + l->length; |
| /* |
| * Advance to the next pid in the array. If this goes off the |
| * end, we're done |
| */ |
| p++; |
| if (p >= end) { |
| return NULL; |
| } else { |
| *pos = cgroup_pid_fry(seq_css(s)->cgroup, *p); |
| return p; |
| } |
| } |
| |
| static int cgroup_pidlist_show(struct seq_file *s, void *v) |
| { |
| seq_printf(s, "%d\n", *(int *)v); |
| |
| return 0; |
| } |
| |
| static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css, |
| struct cftype *cft) |
| { |
| return notify_on_release(css->cgroup); |
| } |
| |
| static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css, |
| struct cftype *cft, u64 val) |
| { |
| if (val) |
| set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
| else |
| clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
| return 0; |
| } |
| |
| static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css, |
| struct cftype *cft) |
| { |
| return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
| } |
| |
| static int cgroup_clone_children_write(struct cgroup_subsys_state *css, |
| struct cftype *cft, u64 val) |
| { |
| if (val) |
| set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
| else |
| clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
| return 0; |
| } |
| |
| /* cgroup core interface files for the default hierarchy */ |
| static struct cftype cgroup_dfl_base_files[] = { |
| { |
| .name = "cgroup.procs", |
| .file_offset = offsetof(struct cgroup, procs_file), |
| .seq_start = cgroup_pidlist_start, |
| .seq_next = cgroup_pidlist_next, |
| .seq_stop = cgroup_pidlist_stop, |
| .seq_show = cgroup_pidlist_show, |
| .private = CGROUP_FILE_PROCS, |
| .write = cgroup_procs_write, |
| }, |
| { |
| .name = "cgroup.controllers", |
| .seq_show = cgroup_controllers_show, |
| }, |
| { |
| .name = "cgroup.subtree_control", |
| .seq_show = cgroup_subtree_control_show, |
| .write = cgroup_subtree_control_write, |
| }, |
| { |
| .name = "cgroup.events", |
| .flags = CFTYPE_NOT_ON_ROOT, |
| .file_offset = offsetof(struct cgroup, events_file), |
| .seq_show = cgroup_events_show, |
| }, |
| { } /* terminate */ |
| }; |
| |
| /* cgroup core interface files for the legacy hierarchies */ |
| static struct cftype cgroup_legacy_base_files[] = { |
| { |
| .name = "cgroup.procs", |
| .seq_start = cgroup_pidlist_start, |
| .seq_next = cgroup_pidlist_next, |
| .seq_stop = cgroup_pidlist_stop, |
| .seq_show = cgroup_pidlist_show, |
| .private = CGROUP_FILE_PROCS, |
| .write = cgroup_procs_write, |
| }, |
| { |
| .name = "cgroup.clone_children", |
| .read_u64 = cgroup_clone_children_read, |
| .write_u64 = cgroup_clone_children_write, |
| }, |
| { |
| .name = "cgroup.sane_behavior", |
| .flags = CFTYPE_ONLY_ON_ROOT, |
| .seq_show = cgroup_sane_behavior_show, |
| }, |
| { |
| .name = "tasks", |
| .seq_start = cgroup_pidlist_start, |
| .seq_next = cgroup_pidlist_next, |
| .seq_stop = cgroup_pidlist_stop, |
| .seq_show = cgroup_pidlist_show, |
| .private = CGROUP_FILE_TASKS, |
| .write = cgroup_tasks_write, |
| }, |
| { |
| .name = "notify_on_release", |
| .read_u64 = cgroup_read_notify_on_release, |
| .write_u64 = cgroup_write_notify_on_release, |
| }, |
| { |
| .name = "release_agent", |
| .flags = CFTYPE_ONLY_ON_ROOT, |
| .seq_show = cgroup_release_agent_show, |
| .write = cgroup_release_agent_write, |
| .max_write_len = PATH_MAX - 1, |
| }, |
| { } /* terminate */ |
| }; |
| |
| /* |
| * css destruction is four-stage process. |
| * |
| * 1. Destruction starts. Killing of the percpu_ref is initiated. |
| * Implemented in kill_css(). |
| * |
| * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs |
| * and thus css_tryget_online() is guaranteed to fail, the css can be |
| * offlined by invoking offline_css(). After offlining, the base ref is |
| * put. Implemented in css_killed_work_fn(). |
| * |
| * 3. When the percpu_ref reaches zero, the only possible remaining |
| * accessors are inside RCU read sections. css_release() schedules the |
| * RCU callback. |
| * |
| * 4. After the grace period, the css can be freed. Implemented in |
| * css_free_work_fn(). |
| * |
| * It is actually hairier because both step 2 and 4 require process context |
| * and thus involve punting to css->destroy_work adding two additional |
| * steps to the already complex sequence. |
| */ |
| static void css_free_work_fn(struct work_struct *work) |
| { |
| struct cgroup_subsys_state *css = |
| container_of(work, struct cgroup_subsys_state, destroy_work); |
| struct cgroup_subsys *ss = css->ss; |
| struct cgroup *cgrp = css->cgroup; |
| |
| percpu_ref_exit(&css->refcnt); |
| |
| if (ss) { |
| /* css free path */ |
| struct cgroup_subsys_state *parent = css->parent; |
| int id = css->id; |
| |
| ss->css_free(css); |
| cgroup_idr_remove(&ss->css_idr, id); |
| cgroup_put(cgrp); |
| |
| if (parent) |
| css_put(parent); |
| } else { |
| /* cgroup free path */ |
| atomic_dec(&cgrp->root->nr_cgrps); |
| cgroup_pidlist_destroy_all(cgrp); |
| cancel_work_sync(&cgrp->release_agent_work); |
| |
| if (cgroup_parent(cgrp)) { |
| /* |
| * We get a ref to the parent, and put the ref when |
| * this cgroup is being freed, so it's guaranteed |
| * that the parent won't be destroyed before its |
| * children. |
| */ |
| cgroup_put(cgroup_parent(cgrp)); |
| kernfs_put(cgrp->kn); |
| kfree(cgrp); |
| } else { |
| /* |
| * This is root cgroup's refcnt reaching zero, |
| * which indicates that the root should be |
| * released. |
| */ |
| cgroup_destroy_root(cgrp->root); |
| } |
| } |
| } |
| |
| static void css_free_rcu_fn(struct rcu_head *rcu_head) |
| { |
| struct cgroup_subsys_state *css = |
| container_of(rcu_head, struct cgroup_subsys_state, rcu_head); |
| |
| INIT_WORK(&css->destroy_work, css_free_work_fn); |
| queue_work(cgroup_destroy_wq, &css->destroy_work); |
| } |
| |
| static void css_release_work_fn(struct work_struct *work) |
| { |
| struct cgroup_subsys_state *css = |
| container_of(work, struct cgroup_subsys_state, destroy_work); |
| struct cgroup_subsys *ss = css->ss; |
| struct cgroup *cgrp = css->cgroup; |
| |
| mutex_lock(&cgroup_mutex); |
| |
| css->flags |= CSS_RELEASED; |
| list_del_rcu(&css->sibling); |
| |
| if (ss) { |
| /* css release path */ |
| cgroup_idr_replace(&ss->css_idr, NULL, css->id); |
| if (ss->css_released) |
| ss->css_released(css); |
| } else { |
| /* cgroup release path */ |
| cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id); |
| cgrp->id = -1; |
| |
| /* |
| * There are two control paths which try to determine |
| * cgroup from dentry without going through kernfs - |
| * cgroupstats_build() and css_tryget_online_from_dir(). |
| * Those are supported by RCU protecting clearing of |
| * cgrp->kn->priv backpointer. |
| */ |
| if (cgrp->kn) |
| RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv, |
| NULL); |
| } |
| |
| mutex_unlock(&cgroup_mutex); |
| |
| call_rcu(&css->rcu_head, css_free_rcu_fn); |
| } |
| |
| static void css_release(struct percpu_ref *ref) |
| { |
| struct cgroup_subsys_state *css = |
| container_of(ref, struct cgroup_subsys_state, refcnt); |
| |
| INIT_WORK(&css->destroy_work, css_release_work_fn); |
| queue_work(cgroup_destroy_wq, &css->destroy_work); |
| } |
| |
| static void init_and_link_css(struct cgroup_subsys_state *css, |
| struct cgroup_subsys *ss, struct cgroup *cgrp) |
| { |
| lockdep_assert_held(&cgroup_mutex); |
| |
| cgroup_get(cgrp); |
| |
| memset(css, 0, sizeof(*css)); |
| css->cgroup = cgrp; |
| css->ss = ss; |
| css->id = -1; |
| INIT_LIST_HEAD(&css->sibling); |
| INIT_LIST_HEAD(&css->children); |
| css->serial_nr = css_serial_nr_next++; |
| atomic_set(&css->online_cnt, 0); |
| |
| if (cgroup_parent(cgrp)) { |
| css->parent = cgroup_css(cgroup_parent(cgrp), ss); |
| css_get(css->parent); |
| } |
| |
| BUG_ON(cgroup_css(cgrp, ss)); |
| } |
| |
| /* invoke ->css_online() on a new CSS and mark it online if successful */ |
| static int online_css(struct cgroup_subsys_state *css) |
| { |
| struct cgroup_subsys *ss = css->ss; |
| int ret = 0; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| if (ss->css_online) |
| ret = ss->css_online(css); |
| if (!ret) { |
| css->flags |= CSS_ONLINE; |
| rcu_assign_pointer(css->cgroup->subsys[ss->id], css); |
| |
| atomic_inc(&css->online_cnt); |
| if (css->parent) |
| atomic_inc(&css->parent->online_cnt); |
| } |
| return ret; |
| } |
| |
| /* if the CSS is online, invoke ->css_offline() on it and mark it offline */ |
| static void offline_css(struct cgroup_subsys_state *css) |
| { |
| struct cgroup_subsys *ss = css->ss; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| if (!(css->flags & CSS_ONLINE)) |
| return; |
| |
| if (ss->css_reset) |
| ss->css_reset(css); |
| |
| if (ss->css_offline) |
| ss->css_offline(css); |
| |
| css->flags &= ~CSS_ONLINE; |
| RCU_INIT_POINTER(css->cgroup->subsys[ss->id], NULL); |
| |
| wake_up_all(&css->cgroup->offline_waitq); |
| } |
| |
| /** |
| * css_create - create a cgroup_subsys_state |
| * @cgrp: the cgroup new css will be associated with |
| * @ss: the subsys of new css |
| * |
| * Create a new css associated with @cgrp - @ss pair. On success, the new |
| * css is online and installed in @cgrp. This function doesn't create the |
| * interface files. Returns 0 on success, -errno on failure. |
| */ |
| static struct cgroup_subsys_state *css_create(struct cgroup *cgrp, |
| struct cgroup_subsys *ss) |
| { |
| struct cgroup *parent = cgroup_parent(cgrp); |
| struct cgroup_subsys_state *parent_css = cgroup_css(parent, ss); |
| struct cgroup_subsys_state *css; |
| int err; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| css = ss->css_alloc(parent_css); |
| if (!css) |
| css = ERR_PTR(-ENOMEM); |
| if (IS_ERR(css)) |
| return css; |
| |
| init_and_link_css(css, ss, cgrp); |
| |
| err = percpu_ref_init(&css->refcnt, css_release, 0, GFP_KERNEL); |
| if (err) |
| goto err_free_css; |
| |
| err = cgroup_idr_alloc(&ss->css_idr, NULL, 2, 0, GFP_KERNEL); |
| if (err < 0) |
| goto err_free_css; |
| css->id = err; |
| |
| /* @css is ready to be brought online now, make it visible */ |
| list_add_tail_rcu(&css->sibling, &parent_css->children); |
| cgroup_idr_replace(&ss->css_idr, css, css->id); |
| |
| err = online_css(css); |
| if (err) |
| goto err_list_del; |
| |
| if (ss->broken_hierarchy && !ss->warned_broken_hierarchy && |
| cgroup_parent(parent)) { |
| pr_warn("%s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n", |
| current->comm, current->pid, ss->name); |
| if (!strcmp(ss->name, "memory")) |
| pr_warn("\"memory\" requires setting use_hierarchy to 1 on the root\n"); |
| ss->warned_broken_hierarchy = true; |
| } |
| |
| return css; |
| |
| err_list_del: |
| list_del_rcu(&css->sibling); |
| err_free_css: |
| call_rcu(&css->rcu_head, css_free_rcu_fn); |
| return ERR_PTR(err); |
| } |
| |
| static struct cgroup *cgroup_create(struct cgroup *parent) |
| { |
| struct cgroup_root *root = parent->root; |
| struct cgroup *cgrp, *tcgrp; |
| int level = parent->level + 1; |
| int ret; |
| |
| /* allocate the cgroup and its ID, 0 is reserved for the root */ |
| cgrp = kzalloc(sizeof(*cgrp) + |
| sizeof(cgrp->ancestor_ids[0]) * (level + 1), GFP_KERNEL); |
| if (!cgrp) |
| return ERR_PTR(-ENOMEM); |
| |
| ret = percpu_ref_init(&cgrp->self.refcnt, css_release, 0, GFP_KERNEL); |
| if (ret) |
| goto out_free_cgrp; |
| |
| /* |
| * Temporarily set the pointer to NULL, so idr_find() won't return |
| * a half-baked cgroup. |
| */ |
| cgrp->id = cgroup_idr_alloc(&root->cgroup_idr, NULL, 2, 0, GFP_KERNEL); |
| if (cgrp->id < 0) { |
| ret = -ENOMEM; |
| goto out_cancel_ref; |
| } |
| |
| init_cgroup_housekeeping(cgrp); |
| |
| cgrp->self.parent = &parent->self; |
| cgrp->root = root; |
| cgrp->level = level; |
| |
| for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp)) |
| cgrp->ancestor_ids[tcgrp->level] = tcgrp->id; |
| |
| if (notify_on_release(parent)) |
| set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
| |
| if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags)) |
| set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); |
| |
| cgrp->self.serial_nr = css_serial_nr_next++; |
| |
| /* allocation complete, commit to creation */ |
| list_add_tail_rcu(&cgrp->self.sibling, &cgroup_parent(cgrp)->self.children); |
| atomic_inc(&root->nr_cgrps); |
| cgroup_get(parent); |
| |
| /* |
| * @cgrp is now fully operational. If something fails after this |
| * point, it'll be released via the normal destruction path. |
| */ |
| cgroup_idr_replace(&root->cgroup_idr, cgrp, cgrp->id); |
| |
| /* |
| * On the default hierarchy, a child doesn't automatically inherit |
| * subtree_control from the parent. Each is configured manually. |
| */ |
| if (!cgroup_on_dfl(cgrp)) |
| cgrp->subtree_control = cgroup_control(cgrp); |
| |
| cgroup_propagate_control(cgrp); |
| |
| /* @cgrp doesn't have dir yet so the following will only create csses */ |
| ret = cgroup_apply_control_enable(cgrp); |
| if (ret) |
| goto out_destroy; |
| |
| return cgrp; |
| |
| out_cancel_ref: |
| percpu_ref_exit(&cgrp->self.refcnt); |
| out_free_cgrp: |
| kfree(cgrp); |
| return ERR_PTR(ret); |
| out_destroy: |
| cgroup_destroy_locked(cgrp); |
| return ERR_PTR(ret); |
| } |
| |
| static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, |
| umode_t mode) |
| { |
| struct cgroup *parent, *cgrp; |
| struct kernfs_node *kn; |
| int ret; |
| |
| /* do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable */ |
| if (strchr(name, '\n')) |
| return -EINVAL; |
| |
| parent = cgroup_kn_lock_live(parent_kn, false); |
| if (!parent) |
| return -ENODEV; |
| |
| cgrp = cgroup_create(parent); |
| if (IS_ERR(cgrp)) { |
| ret = PTR_ERR(cgrp); |
| goto out_unlock; |
| } |
| |
| /* create the directory */ |
| kn = kernfs_create_dir(parent->kn, name, mode, cgrp); |
| if (IS_ERR(kn)) { |
| ret = PTR_ERR(kn); |
| goto out_destroy; |
| } |
| cgrp->kn = kn; |
| |
| /* |
| * This extra ref will be put in cgroup_free_fn() and guarantees |
| * that @cgrp->kn is always accessible. |
| */ |
| kernfs_get(kn); |
| |
| ret = cgroup_kn_set_ugid(kn); |
| if (ret) |
| goto out_destroy; |
| |
| ret = css_populate_dir(&cgrp->self); |
| if (ret) |
| goto out_destroy; |
| |
| ret = cgroup_apply_control_enable(cgrp); |
| if (ret) |
| goto out_destroy; |
| |
| /* let's create and online css's */ |
| kernfs_activate(kn); |
| |
| ret = 0; |
| goto out_unlock; |
| |
| out_destroy: |
| cgroup_destroy_locked(cgrp); |
| out_unlock: |
| cgroup_kn_unlock(parent_kn); |
| return ret; |
| } |
| |
| /* |
| * This is called when the refcnt of a css is confirmed to be killed. |
| * css_tryget_online() is now guaranteed to fail. Tell the subsystem to |
| * initate destruction and put the css ref from kill_css(). |
| */ |
| static void css_killed_work_fn(struct work_struct *work) |
| { |
| struct cgroup_subsys_state *css = |
| container_of(work, struct cgroup_subsys_state, destroy_work); |
| |
| mutex_lock(&cgroup_mutex); |
| |
| do { |
| offline_css(css); |
| css_put(css); |
| /* @css can't go away while we're holding cgroup_mutex */ |
| css = css->parent; |
| } while (css && atomic_dec_and_test(&css->online_cnt)); |
| |
| mutex_unlock(&cgroup_mutex); |
| } |
| |
| /* css kill confirmation processing requires process context, bounce */ |
| static void css_killed_ref_fn(struct percpu_ref *ref) |
| { |
| struct cgroup_subsys_state *css = |
| container_of(ref, struct cgroup_subsys_state, refcnt); |
| |
| if (atomic_dec_and_test(&css->online_cnt)) { |
| INIT_WORK(&css->destroy_work, css_killed_work_fn); |
| queue_work(cgroup_destroy_wq, &css->destroy_work); |
| } |
| } |
| |
| /** |
| * kill_css - destroy a css |
| * @css: css to destroy |
| * |
| * This function initiates destruction of @css by removing cgroup interface |
| * files and putting its base reference. ->css_offline() will be invoked |
| * asynchronously once css_tryget_online() is guaranteed to fail and when |
| * the reference count reaches zero, @css will be released. |
| */ |
| static void kill_css(struct cgroup_subsys_state *css) |
| { |
| lockdep_assert_held(&cgroup_mutex); |
| |
| /* |
| * This must happen before css is disassociated with its cgroup. |
| * See seq_css() for details. |
| */ |
| css_clear_dir(css); |
| |
| /* |
| * Killing would put the base ref, but we need to keep it alive |
| * until after ->css_offline(). |
| */ |
| css_get(css); |
| |
| /* |
| * cgroup core guarantees that, by the time ->css_offline() is |
| * invoked, no new css reference will be given out via |
| * css_tryget_online(). We can't simply call percpu_ref_kill() and |
| * proceed to offlining css's because percpu_ref_kill() doesn't |
| * guarantee that the ref is seen as killed on all CPUs on return. |
| * |
| * Use percpu_ref_kill_and_confirm() to get notifications as each |
| * css is confirmed to be seen as killed on all CPUs. |
| */ |
| percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn); |
| } |
| |
| /** |
| * cgroup_destroy_locked - the first stage of cgroup destruction |
| * @cgrp: cgroup to be destroyed |
| * |
| * css's make use of percpu refcnts whose killing latency shouldn't be |
| * exposed to userland and are RCU protected. Also, cgroup core needs to |
| * guarantee that css_tryget_online() won't succeed by the time |
| * ->css_offline() is invoked. To satisfy all the requirements, |
| * destruction is implemented in the following two steps. |
| * |
| * s1. Verify @cgrp can be destroyed and mark it dying. Remove all |
| * userland visible parts and start killing the percpu refcnts of |
| * css's. Set up so that the next stage will be kicked off once all |
| * the percpu refcnts are confirmed to be killed. |
| * |
| * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the |
| * rest of destruction. Once all cgroup references are gone, the |
| * cgroup is RCU-freed. |
| * |
| * This function implements s1. After this step, @cgrp is gone as far as |
| * the userland is concerned and a new cgroup with the same name may be |
| * created. As cgroup doesn't care about the names internally, this |
| * doesn't cause any problem. |
| */ |
| static int cgroup_destroy_locked(struct cgroup *cgrp) |
| __releases(&cgroup_mutex) __acquires(&cgroup_mutex) |
| { |
| struct cgroup_subsys_state *css; |
| struct cgrp_cset_link *link; |
| int ssid; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| /* |
| * Only migration can raise populated from zero and we're already |
| * holding cgroup_mutex. |
| */ |
| if (cgroup_is_populated(cgrp)) |
| return -EBUSY; |
| |
| /* |
| * Make sure there's no live children. We can't test emptiness of |
| * ->self.children as dead children linger on it while being |
| * drained; otherwise, "rmdir parent/child parent" may fail. |
| */ |
| if (css_has_online_children(&cgrp->self)) |
| return -EBUSY; |
| |
| /* |
| * Mark @cgrp and the associated csets dead. The former prevents |
| * further task migration and child creation by disabling |
| * cgroup_lock_live_group(). The latter makes the csets ignored by |
| * the migration path. |
| */ |
| cgrp->self.flags &= ~CSS_ONLINE; |
| |
| spin_lock_irq(&css_set_lock); |
| list_for_each_entry(link, &cgrp->cset_links, cset_link) |
| link->cset->dead = true; |
| spin_unlock_irq(&css_set_lock); |
| |
| /* initiate massacre of all css's */ |
| for_each_css(css, ssid, cgrp) |
| kill_css(css); |
| |
| /* |
| * Remove @cgrp directory along with the base files. @cgrp has an |
| * extra ref on its kn. |
| */ |
| kernfs_remove(cgrp->kn); |
| |
| check_for_release(cgroup_parent(cgrp)); |
| |
| /* put the base reference */ |
| percpu_ref_kill(&cgrp->self.refcnt); |
| |
| return 0; |
| }; |
| |
| static int cgroup_rmdir(struct kernfs_node *kn) |
| { |
| struct cgroup *cgrp; |
| int ret = 0; |
| |
| cgrp = cgroup_kn_lock_live(kn, false); |
| if (!cgrp) |
| return 0; |
| |
| ret = cgroup_destroy_locked(cgrp); |
| |
| cgroup_kn_unlock(kn); |
| return ret; |
| } |
| |
| static struct kernfs_syscall_ops cgroup_kf_syscall_ops = { |
| .remount_fs = cgroup_remount, |
| .show_options = cgroup_show_options, |
| .mkdir = cgroup_mkdir, |
| .rmdir = cgroup_rmdir, |
| .rename = cgroup_rename, |
| .show_path = cgroup_show_path, |
| }; |
| |
| static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early) |
| { |
| struct cgroup_subsys_state *css; |
| |
| pr_debug("Initializing cgroup subsys %s\n", ss->name); |
| |
| mutex_lock(&cgroup_mutex); |
| |
| idr_init(&ss->css_idr); |
| INIT_LIST_HEAD(&ss->cfts); |
| |
| /* Create the root cgroup state for this subsystem */ |
| ss->root = &cgrp_dfl_root; |
| css = ss->css_alloc(cgroup_css(&cgrp_dfl_root.cgrp, ss)); |
| /* We don't handle early failures gracefully */ |
| BUG_ON(IS_ERR(css)); |
| init_and_link_css(css, ss, &cgrp_dfl_root.cgrp); |
| |
| /* |
| * Root csses are never destroyed and we can't initialize |
| * percpu_ref during early init. Disable refcnting. |
| */ |
| css->flags |= CSS_NO_REF; |
| |
| if (early) { |
| /* allocation can't be done safely during early init */ |
| css->id = 1; |
| } else { |
| css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, GFP_KERNEL); |
| BUG_ON(css->id < 0); |
| } |
| |
| /* Update the init_css_set to contain a subsys |
| * pointer to this state - since the subsystem is |
| * newly registered, all tasks and hence the |
| * init_css_set is in the subsystem's root cgroup. */ |
| init_css_set.subsys[ss->id] = css; |
| |
| have_fork_callback |= (bool)ss->fork << ss->id; |
| have_exit_callback |= (bool)ss->exit << ss->id; |
| have_free_callback |= (bool)ss->free << ss->id; |
| have_canfork_callback |= (bool)ss->can_fork << ss->id; |
| |
| /* At system boot, before all subsystems have been |
| * registered, no tasks have been forked, so we don't |
| * need to invoke fork callbacks here. */ |
| BUG_ON(!list_empty(&init_task.tasks)); |
| |
| BUG_ON(online_css(css)); |
| |
| mutex_unlock(&cgroup_mutex); |
| } |
| |
| /** |
| * cgroup_init_early - cgroup initialization at system boot |
| * |
| * Initialize cgroups at system boot, and initialize any |
| * subsystems that request early init. |
| */ |
| int __init cgroup_init_early(void) |
| { |
| static struct cgroup_sb_opts __initdata opts; |
| struct cgroup_subsys *ss; |
| int i; |
| |
| init_cgroup_root(&cgrp_dfl_root, &opts); |
| cgrp_dfl_root.cgrp.self.flags |= CSS_NO_REF; |
| |
| RCU_INIT_POINTER(init_task.cgroups, &init_css_set); |
| |
| for_each_subsys(ss, i) { |
| WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id, |
| "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p id:name=%d:%s\n", |
| i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free, |
| ss->id, ss->name); |
| WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN, |
| "cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]); |
| |
| ss->id = i; |
| ss->name = cgroup_subsys_name[i]; |
| if (!ss->legacy_name) |
| ss->legacy_name = cgroup_subsys_name[i]; |
| |
| if (ss->early_init) |
| cgroup_init_subsys(ss, true); |
| } |
| return 0; |
| } |
| |
| static u16 cgroup_disable_mask __initdata; |
| |
| /** |
| * cgroup_init - cgroup initialization |
| * |
| * Register cgroup filesystem and /proc file, and initialize |
| * any subsystems that didn't request early init. |
| */ |
| int __init cgroup_init(void) |
| { |
| struct cgroup_subsys *ss; |
| int ssid; |
| |
| BUILD_BUG_ON(CGROUP_SUBSYS_COUNT > 16); |
| BUG_ON(percpu_init_rwsem(&cgroup_threadgroup_rwsem)); |
| BUG_ON(cgroup_init_cftypes(NULL, cgroup_dfl_base_files)); |
| BUG_ON(cgroup_init_cftypes(NULL, cgroup_legacy_base_files)); |
| |
| get_user_ns(init_cgroup_ns.user_ns); |
| |
| mutex_lock(&cgroup_mutex); |
| |
| /* |
| * Add init_css_set to the hash table so that dfl_root can link to |
| * it during init. |
| */ |
| hash_add(css_set_table, &init_css_set.hlist, |
| css_set_hash(init_css_set.subsys)); |
| |
| BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0)); |
| |
| mutex_unlock(&cgroup_mutex); |
| |
| for_each_subsys(ss, ssid) { |
| if (ss->early_init) { |
| struct cgroup_subsys_state *css = |
| init_css_set.subsys[ss->id]; |
| |
| css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, |
| GFP_KERNEL); |
| BUG_ON(css->id < 0); |
| } else { |
| cgroup_init_subsys(ss, false); |
| } |
| |
| list_add_tail(&init_css_set.e_cset_node[ssid], |
| &cgrp_dfl_root.cgrp.e_csets[ssid]); |
| |
| /* |
| * Setting dfl_root subsys_mask needs to consider the |
| * disabled flag and cftype registration needs kmalloc, |
| * both of which aren't available during early_init. |
| */ |
| if (cgroup_disable_mask & (1 << ssid)) { |
| static_branch_disable(cgroup_subsys_enabled_key[ssid]); |
| printk(KERN_INFO "Disabling %s control group subsystem\n", |
| ss->name); |
| continue; |
| } |
| |
| if (cgroup_ssid_no_v1(ssid)) |
| printk(KERN_INFO "Disabling %s control group subsystem in v1 mounts\n", |
| ss->name); |
| |
| cgrp_dfl_root.subsys_mask |= 1 << ss->id; |
| |
| if (ss->implicit_on_dfl) |
| cgrp_dfl_implicit_ss_mask |= 1 << ss->id; |
| else if (!ss->dfl_cftypes) |
| cgrp_dfl_inhibit_ss_mask |= 1 << ss->id; |
| |
| if (ss->dfl_cftypes == ss->legacy_cftypes) { |
| WARN_ON(cgroup_add_cftypes(ss, ss->dfl_cftypes)); |
| } else { |
| WARN_ON(cgroup_add_dfl_cftypes(ss, ss->dfl_cftypes)); |
| WARN_ON(cgroup_add_legacy_cftypes(ss, ss->legacy_cftypes)); |
| } |
| |
| if (ss->bind) |
| ss->bind(init_css_set.subsys[ssid]); |
| } |
| |
| /* init_css_set.subsys[] has been updated, re-hash */ |
| hash_del(&init_css_set.hlist); |
| hash_add(css_set_table, &init_css_set.hlist, |
| css_set_hash(init_css_set.subsys)); |
| |
| WARN_ON(sysfs_create_mount_point(fs_kobj, "cgroup")); |
| WARN_ON(register_filesystem(&cgroup_fs_type)); |
| WARN_ON(register_filesystem(&cgroup2_fs_type)); |
| WARN_ON(!proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations)); |
| |
| return 0; |
| } |
| |
| static int __init cgroup_wq_init(void) |
| { |
| /* |
| * There isn't much point in executing destruction path in |
| * parallel. Good chunk is serialized with cgroup_mutex anyway. |
| * Use 1 for @max_active. |
| * |
| * We would prefer to do this in cgroup_init() above, but that |
| * is called before init_workqueues(): so leave this until after. |
| */ |
| cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1); |
| BUG_ON(!cgroup_destroy_wq); |
| |
| /* |
| * Used to destroy pidlists and separate to serve as flush domain. |
| * Cap @max_active to 1 too. |
| */ |
| cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy", |
| 0, 1); |
| BUG_ON(!cgroup_pidlist_destroy_wq); |
| |
| return 0; |
| } |
| core_initcall(cgroup_wq_init); |
| |
| /* |
| * proc_cgroup_show() |
| * - Print task's cgroup paths into seq_file, one line for each hierarchy |
| * - Used for /proc/<pid>/cgroup. |
| */ |
| int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns, |
| struct pid *pid, struct task_struct *tsk) |
| { |
| char *buf, *path; |
| int retval; |
| struct cgroup_root *root; |
| |
| retval = -ENOMEM; |
| buf = kmalloc(PATH_MAX, GFP_KERNEL); |
| if (!buf) |
| goto out; |
| |
| mutex_lock(&cgroup_mutex); |
| spin_lock_irq(&css_set_lock); |
| |
| for_each_root(root) { |
| struct cgroup_subsys *ss; |
| struct cgroup *cgrp; |
| int ssid, count = 0; |
| |
| if (root == &cgrp_dfl_root && !cgrp_dfl_visible) |
| continue; |
| |
| seq_printf(m, "%d:", root->hierarchy_id); |
| if (root != &cgrp_dfl_root) |
| for_each_subsys(ss, ssid) |
| if (root->subsys_mask & (1 << ssid)) |
| seq_printf(m, "%s%s", count++ ? "," : "", |
| ss->legacy_name); |
| if (strlen(root->name)) |
| seq_printf(m, "%sname=%s", count ? "," : "", |
| root->name); |
| seq_putc(m, ':'); |
| |
| cgrp = task_cgroup_from_root(tsk, root); |
| |
| /* |
| * On traditional hierarchies, all zombie tasks show up as |
| * belonging to the root cgroup. On the default hierarchy, |
| * while a zombie doesn't show up in "cgroup.procs" and |
| * thus can't be migrated, its /proc/PID/cgroup keeps |
| * reporting the cgroup it belonged to before exiting. If |
| * the cgroup is removed before the zombie is reaped, |
| * " (deleted)" is appended to the cgroup path. |
| */ |
| if (cgroup_on_dfl(cgrp) || !(tsk->flags & PF_EXITING)) { |
| path = cgroup_path_ns_locked(cgrp, buf, PATH_MAX, |
| current->nsproxy->cgroup_ns); |
| if (!path) { |
| retval = -ENAMETOOLONG; |
| goto out_unlock; |
| } |
| } else { |
| path = "/"; |
| } |
| |
| seq_puts(m, path); |
| |
| if (cgroup_on_dfl(cgrp) && cgroup_is_dead(cgrp)) |
| seq_puts(m, " (deleted)\n"); |
| else |
| seq_putc(m, '\n'); |
| } |
| |
| retval = 0; |
| out_unlock: |
| spin_unlock_irq(&css_set_lock); |
| mutex_unlock(&cgroup_mutex); |
| kfree(buf); |
| out: |
| return retval; |
| } |
| |
| /* Display information about each subsystem and each hierarchy */ |
| static int proc_cgroupstats_show(struct seq_file *m, void *v) |
| { |
| struct cgroup_subsys *ss; |
| int i; |
| |
| seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); |
| /* |
| * ideally we don't want subsystems moving around while we do this. |
| * cgroup_mutex is also necessary to guarantee an atomic snapshot of |
| * subsys/hierarchy state. |
| */ |
| mutex_lock(&cgroup_mutex); |
| |
| for_each_subsys(ss, i) |
| seq_printf(m, "%s\t%d\t%d\t%d\n", |
| ss->legacy_name, ss->root->hierarchy_id, |
| atomic_read(&ss->root->nr_cgrps), |
| cgroup_ssid_enabled(i)); |
| |
| mutex_unlock(&cgroup_mutex); |
| return 0; |
| } |
| |
| static int cgroupstats_open(struct inode *inode, struct file *file) |
| { |
| return single_open(file, proc_cgroupstats_show, NULL); |
| } |
| |
| static const struct file_operations proc_cgroupstats_operations = { |
| .open = cgroupstats_open, |
| .read = seq_read, |
| .llseek = seq_lseek, |
| .release = single_release, |
| }; |
| |
| /** |
| * cgroup_fork - initialize cgroup related fields during copy_process() |
| * @child: pointer to task_struct of forking parent process. |
| * |
| * A task is associated with the init_css_set until cgroup_post_fork() |
| * attaches it to the parent's css_set. Empty cg_list indicates that |
| * @child isn't holding reference to its css_set. |
| */ |
| void cgroup_fork(struct task_struct *child) |
| { |
| RCU_INIT_POINTER(child->cgroups, &init_css_set); |
| INIT_LIST_HEAD(&child->cg_list); |
| } |
| |
| /** |
| * cgroup_can_fork - called on a new task before the process is exposed |
| * @child: the task in question. |
| * |
| * This calls the subsystem can_fork() callbacks. If the can_fork() callback |
| * returns an error, the fork aborts with that error code. This allows for |
| * a cgroup subsystem to conditionally allow or deny new forks. |
| */ |
| int cgroup_can_fork(struct task_struct *child) |
| { |
| struct cgroup_subsys *ss; |
| int i, j, ret; |
| |
| do_each_subsys_mask(ss, i, have_canfork_callback) { |
| ret = ss->can_fork(child); |
| if (ret) |
| goto out_revert; |
| } while_each_subsys_mask(); |
| |
| return 0; |
| |
| out_revert: |
| for_each_subsys(ss, j) { |
| if (j >= i) |
| break; |
| if (ss->cancel_fork) |
| ss->cancel_fork(child); |
| } |
| |
| return ret; |
| } |
| |
| /** |
| * cgroup_cancel_fork - called if a fork failed after cgroup_can_fork() |
| * @child: the task in question |
| * |
| * This calls the cancel_fork() callbacks if a fork failed *after* |
| * cgroup_can_fork() succeded. |
| */ |
| void cgroup_cancel_fork(struct task_struct *child) |
| { |
| struct cgroup_subsys *ss; |
| int i; |
| |
| for_each_subsys(ss, i) |
| if (ss->cancel_fork) |
| ss->cancel_fork(child); |
| } |
| |
| /** |
| * cgroup_post_fork - called on a new task after adding it to the task list |
| * @child: the task in question |
| * |
| * Adds the task to the list running through its css_set if necessary and |
| * call the subsystem fork() callbacks. Has to be after the task is |
| * visible on the task list in case we race with the first call to |
| * cgroup_task_iter_start() - to guarantee that the new task ends up on its |
| * list. |
| */ |
| void cgroup_post_fork(struct task_struct *child) |
| { |
| struct cgroup_subsys *ss; |
| int i; |
| |
| /* |
| * This may race against cgroup_enable_task_cg_lists(). As that |
| * function sets use_task_css_set_links before grabbing |
| * tasklist_lock and we just went through tasklist_lock to add |
| * @child, it's guaranteed that either we see the set |
| * use_task_css_set_links or cgroup_enable_task_cg_lists() sees |
| * @child during its iteration. |
| * |
| * If we won the race, @child is associated with %current's |
| * css_set. Grabbing css_set_lock guarantees both that the |
| * association is stable, and, on completion of the parent's |
| * migration, @child is visible in the source of migration or |
| * already in the destination cgroup. This guarantee is necessary |
| * when implementing operations which need to migrate all tasks of |
| * a cgroup to another. |
| * |
| * Note that if we lose to cgroup_enable_task_cg_lists(), @child |
| * will remain in init_css_set. This is safe because all tasks are |
| * in the init_css_set before cg_links is enabled and there's no |
| * operation which transfers all tasks out of init_css_set. |
| */ |
| if (use_task_css_set_links) { |
| struct css_set *cset; |
| |
| spin_lock_irq(&css_set_lock); |
| cset = task_css_set(current); |
| if (list_empty(&child->cg_list)) { |
| get_css_set(cset); |
| css_set_move_task(child, NULL, cset, false); |
| } |
| spin_unlock_irq(&css_set_lock); |
| } |
| |
| /* |
| * Call ss->fork(). This must happen after @child is linked on |
| * css_set; otherwise, @child might change state between ->fork() |
| * and addition to css_set. |
| */ |
| do_each_subsys_mask(ss, i, have_fork_callback) { |
| ss->fork(child); |
| } while_each_subsys_mask(); |
| } |
| |
| /** |
| * cgroup_exit - detach cgroup from exiting task |
| * @tsk: pointer to task_struct of exiting process |
| * |
| * Description: Detach cgroup from @tsk and release it. |
| * |
| * Note that cgroups marked notify_on_release force every task in |
| * them to take the global cgroup_mutex mutex when exiting. |
| * This could impact scaling on very large systems. Be reluctant to |
| * use notify_on_release cgroups where very high task exit scaling |
| * is required on large systems. |
| * |
| * We set the exiting tasks cgroup to the root cgroup (top_cgroup). We |
| * call cgroup_exit() while the task is still competent to handle |
| * notify_on_release(), then leave the task attached to the root cgroup in |
| * each hierarchy for the remainder of its exit. No need to bother with |
| * init_css_set refcnting. init_css_set never goes away and we can't race |
| * with migration path - PF_EXITING is visible to migration path. |
| */ |
| void cgroup_exit(struct task_struct *tsk) |
| { |
| struct cgroup_subsys *ss; |
| struct css_set *cset; |
| int i; |
| |
| /* |
| * Unlink from @tsk from its css_set. As migration path can't race |
| * with us, we can check css_set and cg_list without synchronization. |
| */ |
| cset = task_css_set(tsk); |
| |
| if (!list_empty(&tsk->cg_list)) { |
| spin_lock_irq(&css_set_lock); |
| css_set_move_task(tsk, cset, NULL, false); |
| spin_unlock_irq(&css_set_lock); |
| } else { |
| get_css_set(cset); |
| } |
| |
| /* see cgroup_post_fork() for details */ |
| do_each_subsys_mask(ss, i, have_exit_callback) { |
| ss->exit(tsk); |
| } while_each_subsys_mask(); |
| } |
| |
| void cgroup_free(struct task_struct *task) |
| { |
| struct css_set *cset = task_css_set(task); |
| struct cgroup_subsys *ss; |
| int ssid; |
| |
| do_each_subsys_mask(ss, ssid, have_free_callback) { |
| ss->free(task); |
| } while_each_subsys_mask(); |
| |
| put_css_set(cset); |
| } |
| |
| static void check_for_release(struct cgroup *cgrp) |
| { |
| if (notify_on_release(cgrp) && !cgroup_is_populated(cgrp) && |
| !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp)) |
| schedule_work(&cgrp->release_agent_work); |
| } |
| |
| /* |
| * Notify userspace when a cgroup is released, by running the |
| * configured release agent with the name of the cgroup (path |
| * relative to the root of cgroup file system) as the argument. |
| * |
| * Most likely, this user command will try to rmdir this cgroup. |
| * |
| * This races with the possibility that some other task will be |
| * attached to this cgroup before it is removed, or that some other |
| * user task will 'mkdir' a child cgroup of this cgroup. That's ok. |
| * The presumed 'rmdir' will fail quietly if this cgroup is no longer |
| * unused, and this cgroup will be reprieved from its death sentence, |
| * to continue to serve a useful existence. Next time it's released, |
| * we will get notified again, if it still has 'notify_on_release' set. |
| * |
| * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which |
| * means only wait until the task is successfully execve()'d. The |
| * separate release agent task is forked by call_usermodehelper(), |
| * then control in this thread returns here, without waiting for the |
| * release agent task. We don't bother to wait because the caller of |
| * this routine has no use for the exit status of the release agent |
| * task, so no sense holding our caller up for that. |
| */ |
| static void cgroup_release_agent(struct work_struct *work) |
| { |
| struct cgroup *cgrp = |
| container_of(work, struct cgroup, release_agent_work); |
| char *pathbuf = NULL, *agentbuf = NULL, *path; |
| char *argv[3], *envp[3]; |
| |
| mutex_lock(&cgroup_mutex); |
| |
| pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); |
| agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); |
| if (!pathbuf || !agentbuf) |
| goto out; |
| |
| spin_lock_irq(&css_set_lock); |
| path = cgroup_path_ns_locked(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns); |
| spin_unlock_irq(&css_set_lock); |
| if (!path) |
| goto out; |
| |
| argv[0] = agentbuf; |
| argv[1] = path; |
| argv[2] = NULL; |
| |
| /* minimal command environment */ |
| envp[0] = "HOME=/"; |
| envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; |
| envp[2] = NULL; |
| |
| mutex_unlock(&cgroup_mutex); |
| call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); |
| goto out_free; |
| out: |
| mutex_unlock(&cgroup_mutex); |
| out_free: |
| kfree(agentbuf); |
| kfree(pathbuf); |
| } |
| |
| static int __init cgroup_disable(char *str) |
| { |
| struct cgroup_subsys *ss; |
| char *token; |
| int i; |
| |
| while ((token = strsep(&str, ",")) != NULL) { |
| if (!*token) |
| continue; |
| |
| for_each_subsys(ss, i) { |
| if (strcmp(token, ss->name) && |
| strcmp(token, ss->legacy_name)) |
| continue; |
| cgroup_disable_mask |= 1 << i; |
| } |
| } |
| return 1; |
| } |
| __setup("cgroup_disable=", cgroup_disable); |
| |
| static int __init cgroup_no_v1(char *str) |
| { |
| struct cgroup_subsys *ss; |
| char *token; |
| int i; |
| |
| while ((token = strsep(&str, ",")) != NULL) { |
| if (!*token) |
| continue; |
| |
| if (!strcmp(token, "all")) { |
| cgroup_no_v1_mask = U16_MAX; |
| break; |
| } |
| |
| for_each_subsys(ss, i) { |
| if (strcmp(token, ss->name) && |
| strcmp(token, ss->legacy_name)) |
| continue; |
| |
| cgroup_no_v1_mask |= 1 << i; |
| } |
| } |
| return 1; |
| } |
| __setup("cgroup_no_v1=", cgroup_no_v1); |
| |
| /** |
| * css_tryget_online_from_dir - get corresponding css from a cgroup dentry |
| * @dentry: directory dentry of interest |
| * @ss: subsystem of interest |
| * |
| * If @dentry is a directory for a cgroup which has @ss enabled on it, try |
| * to get the corresponding css and return it. If such css doesn't exist |
| * or can't be pinned, an ERR_PTR value is returned. |
| */ |
| struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry, |
| struct cgroup_subsys *ss) |
| { |
| struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
| struct file_system_type *s_type = dentry->d_sb->s_type; |
| struct cgroup_subsys_state *css = NULL; |
| struct cgroup *cgrp; |
| |
| /* is @dentry a cgroup dir? */ |
| if ((s_type != &cgroup_fs_type && s_type != &cgroup2_fs_type) || |
| !kn || kernfs_type(kn) != KERNFS_DIR) |
| return ERR_PTR(-EBADF); |
| |
| rcu_read_lock(); |
| |
| /* |
| * This path doesn't originate from kernfs and @kn could already |
| * have been or be removed at any point. @kn->priv is RCU |
| * protected for this access. See css_release_work_fn() for details. |
| */ |
| cgrp = rcu_dereference(kn->priv); |
| if (cgrp) |
| css = cgroup_css(cgrp, ss); |
| |
| if (!css || !css_tryget_online(css)) |
| css = ERR_PTR(-ENOENT); |
| |
| rcu_read_unlock(); |
| return css; |
| } |
| |
| /** |
| * css_from_id - lookup css by id |
| * @id: the cgroup id |
| * @ss: cgroup subsys to be looked into |
| * |
| * Returns the css if there's valid one with @id, otherwise returns NULL. |
| * Should be called under rcu_read_lock(). |
| */ |
| struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss) |
| { |
| WARN_ON_ONCE(!rcu_read_lock_held()); |
| return idr_find(&ss->css_idr, id); |
| } |
| |
| /** |
| * cgroup_get_from_path - lookup and get a cgroup from its default hierarchy path |
| * @path: path on the default hierarchy |
| * |
| * Find the cgroup at @path on the default hierarchy, increment its |
| * reference count and return it. Returns pointer to the found cgroup on |
| * success, ERR_PTR(-ENOENT) if @path doens't exist and ERR_PTR(-ENOTDIR) |
| * if @path points to a non-directory. |
| */ |
| struct cgroup *cgroup_get_from_path(const char *path) |
| { |
| struct kernfs_node *kn; |
| struct cgroup *cgrp; |
| |
| mutex_lock(&cgroup_mutex); |
| |
| kn = kernfs_walk_and_get(cgrp_dfl_root.cgrp.kn, path); |
| if (kn) { |
| if (kernfs_type(kn) == KERNFS_DIR) { |
| cgrp = kn->priv; |
| cgroup_get(cgrp); |
| } else { |
| cgrp = ERR_PTR(-ENOTDIR); |
| } |
| kernfs_put(kn); |
| } else { |
| cgrp = ERR_PTR(-ENOENT); |
| } |
| |
| mutex_unlock(&cgroup_mutex); |
| return cgrp; |
| } |
| EXPORT_SYMBOL_GPL(cgroup_get_from_path); |
| |
| /** |
| * cgroup_get_from_fd - get a cgroup pointer from a fd |
| * @fd: fd obtained by open(cgroup2_dir) |
| * |
| * Find the cgroup from a fd which should be obtained |
| * by opening a cgroup directory. Returns a pointer to the |
| * cgroup on success. ERR_PTR is returned if the cgroup |
| * cannot be found. |
| */ |
| struct cgroup *cgroup_get_from_fd(int fd) |
| { |
| struct cgroup_subsys_state *css; |
| struct cgroup *cgrp; |
| struct file *f; |
| |
| f = fget_raw(fd); |
| if (!f) |
| return ERR_PTR(-EBADF); |
| |
| css = css_tryget_online_from_dir(f->f_path.dentry, NULL); |
| fput(f); |
| if (IS_ERR(css)) |
| return ERR_CAST(css); |
| |
| cgrp = css->cgroup; |
| if (!cgroup_on_dfl(cgrp)) { |
| cgroup_put(cgrp); |
| return ERR_PTR(-EBADF); |
| } |
| |
| return cgrp; |
| } |
| EXPORT_SYMBOL_GPL(cgroup_get_from_fd); |
| |
| /* |
| * sock->sk_cgrp_data handling. For more info, see sock_cgroup_data |
| * definition in cgroup-defs.h. |
| */ |
| #ifdef CONFIG_SOCK_CGROUP_DATA |
| |
| #if defined(CONFIG_CGROUP_NET_PRIO) || defined(CONFIG_CGROUP_NET_CLASSID) |
| |
| DEFINE_SPINLOCK(cgroup_sk_update_lock); |
| static bool cgroup_sk_alloc_disabled __read_mostly; |
| |
| void cgroup_sk_alloc_disable(void) |
| { |
| if (cgroup_sk_alloc_disabled) |
| return; |
| pr_info("cgroup: disabling cgroup2 socket matching due to net_prio or net_cls activation\n"); |
| cgroup_sk_alloc_disabled = true; |
| } |
| |
| #else |
| |
| #define cgroup_sk_alloc_disabled false |
| |
| #endif |
| |
| void cgroup_sk_alloc(struct sock_cgroup_data *skcd) |
| { |
| if (cgroup_sk_alloc_disabled) |
| return; |
| |
| /* Socket clone path */ |
| if (skcd->val) { |
| cgroup_get(sock_cgroup_ptr(skcd)); |
| return; |
| } |
| |
| rcu_read_lock(); |
| |
| while (true) { |
| struct css_set *cset; |
| |
| cset = task_css_set(current); |
| if (likely(cgroup_tryget(cset->dfl_cgrp))) { |
| skcd->val = (unsigned long)cset->dfl_cgrp; |
| break; |
| } |
| cpu_relax(); |
| } |
| |
| rcu_read_unlock(); |
| } |
| |
| void cgroup_sk_free(struct sock_cgroup_data *skcd) |
| { |
| cgroup_put(sock_cgroup_ptr(skcd)); |
| } |
| |
| #endif /* CONFIG_SOCK_CGROUP_DATA */ |
| |
| /* cgroup namespaces */ |
| |
| static struct cgroup_namespace *alloc_cgroup_ns(void) |
| { |
| struct cgroup_namespace *new_ns; |
| int ret; |
| |
| new_ns = kzalloc(sizeof(struct cgroup_namespace), GFP_KERNEL); |
| if (!new_ns) |
| return ERR_PTR(-ENOMEM); |
| ret = ns_alloc_inum(&new_ns->ns); |
| if (ret) { |
| kfree(new_ns); |
| return ERR_PTR(ret); |
| } |
| atomic_set(&new_ns->count, 1); |
| new_ns->ns.ops = &cgroupns_operations; |
| return new_ns; |
| } |
| |
| void free_cgroup_ns(struct cgroup_namespace *ns) |
| { |
| put_css_set(ns->root_cset); |
| put_user_ns(ns->user_ns); |
| ns_free_inum(&ns->ns); |
| kfree(ns); |
| } |
| EXPORT_SYMBOL(free_cgroup_ns); |
| |
| struct cgroup_namespace *copy_cgroup_ns(unsigned long flags, |
| struct user_namespace *user_ns, |
| struct cgroup_namespace *old_ns) |
| { |
| struct cgroup_namespace *new_ns; |
| struct css_set *cset; |
| |
| BUG_ON(!old_ns); |
| |
| if (!(flags & CLONE_NEWCGROUP)) { |
| get_cgroup_ns(old_ns); |
| return old_ns; |
| } |
| |
| /* Allow only sysadmin to create cgroup namespace. */ |
| if (!ns_capable(user_ns, CAP_SYS_ADMIN)) |
| return ERR_PTR(-EPERM); |
| |
| /* It is not safe to take cgroup_mutex here */ |
| spin_lock_irq(&css_set_lock); |
| cset = task_css_set(current); |
| get_css_set(cset); |
| spin_unlock_irq(&css_set_lock); |
| |
| new_ns = alloc_cgroup_ns(); |
| if (IS_ERR(new_ns)) { |
| put_css_set(cset); |
| return new_ns; |
| } |
| |
| new_ns->user_ns = get_user_ns(user_ns); |
| new_ns->root_cset = cset; |
| |
| return new_ns; |
| } |
| |
| static inline struct cgroup_namespace *to_cg_ns(struct ns_common *ns) |
| { |
| return container_of(ns, struct cgroup_namespace, ns); |
| } |
| |
| static int cgroupns_install(struct nsproxy *nsproxy, struct ns_common *ns) |
| { |
| struct cgroup_namespace *cgroup_ns = to_cg_ns(ns); |
| |
| if (!ns_capable(current_user_ns(), CAP_SYS_ADMIN) || |
| !ns_capable(cgroup_ns->user_ns, CAP_SYS_ADMIN)) |
| return -EPERM; |
| |
| /* Don't need to do anything if we are attaching to our own cgroupns. */ |
| if (cgroup_ns == nsproxy->cgroup_ns) |
| return 0; |
| |
| get_cgroup_ns(cgroup_ns); |
| put_cgroup_ns(nsproxy->cgroup_ns); |
| nsproxy->cgroup_ns = cgroup_ns; |
| |
| return 0; |
| } |
| |
| static struct ns_common *cgroupns_get(struct task_struct *task) |
| { |
| struct cgroup_namespace *ns = NULL; |
| struct nsproxy *nsproxy; |
| |
| task_lock(task); |
| nsproxy = task->nsproxy; |
| if (nsproxy) { |
| ns = nsproxy->cgroup_ns; |
| get_cgroup_ns(ns); |
| } |
| task_unlock(task); |
| |
| return ns ? &ns->ns : NULL; |
| } |
| |
| static void cgroupns_put(struct ns_common *ns) |
| { |
| put_cgroup_ns(to_cg_ns(ns)); |
| } |
| |
| const struct proc_ns_operations cgroupns_operations = { |
| .name = "cgroup", |
| .type = CLONE_NEWCGROUP, |
| .get = cgroupns_get, |
| .put = cgroupns_put, |
| .install = cgroupns_install, |
| }; |
| |
| static __init int cgroup_namespaces_init(void) |
| { |
| return 0; |
| } |
| subsys_initcall(cgroup_namespaces_init); |
| |
| #ifdef CONFIG_CGROUP_DEBUG |
| static struct cgroup_subsys_state * |
| debug_css_alloc(struct cgroup_subsys_state *parent_css) |
| { |
| struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); |
| |
| if (!css) |
| return ERR_PTR(-ENOMEM); |
| |
| return css; |
| } |
| |
| static void debug_css_free(struct cgroup_subsys_state *css) |
| { |
| kfree(css); |
| } |
| |
| static u64 debug_taskcount_read(struct cgroup_subsys_state *css, |
| struct cftype *cft) |
| { |
| return cgroup_task_count(css->cgroup); |
| } |
| |
| static u64 current_css_set_read(struct cgroup_subsys_state *css, |
| struct cftype *cft) |
| { |
| return (u64)(unsigned long)current->cgroups; |
| } |
| |
| static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css, |
| struct cftype *cft) |
| { |
| u64 count; |
| |
| rcu_read_lock(); |
| count = atomic_read(&task_css_set(current)->refcount); |
| rcu_read_unlock(); |
| return count; |
| } |
| |
| static int current_css_set_cg_links_read(struct seq_file *seq, void *v) |
| { |
| struct cgrp_cset_link *link; |
| struct css_set *cset; |
| char *name_buf; |
| |
| name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL); |
| if (!name_buf) |
| return -ENOMEM; |
| |
| spin_lock_irq(&css_set_lock); |
| rcu_read_lock(); |
| cset = rcu_dereference(current->cgroups); |
| list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { |
| struct cgroup *c = link->cgrp; |
| |
| cgroup_name(c, name_buf, NAME_MAX + 1); |
| seq_printf(seq, "Root %d group %s\n", |
| c->root->hierarchy_id, name_buf); |
| } |
| rcu_read_unlock(); |
| spin_unlock_irq(&css_set_lock); |
| kfree(name_buf); |
| return 0; |
| } |
| |
| #define MAX_TASKS_SHOWN_PER_CSS 25 |
| static int cgroup_css_links_read(struct seq_file *seq, void *v) |
| { |
| struct cgroup_subsys_state *css = seq_css(seq); |
| struct cgrp_cset_link *link; |
| |
| spin_lock_irq(&css_set_lock); |
| list_for_each_entry(link, &css->cgroup->cset_links, cset_link) { |
| struct css_set *cset = link->cset; |
| struct task_struct *task; |
| int count = 0; |
| |
| seq_printf(seq, "css_set %p\n", cset); |
| |
| list_for_each_entry(task, &cset->tasks, cg_list) { |
| if (count++ > MAX_TASKS_SHOWN_PER_CSS) |
| goto overflow; |
| seq_printf(seq, " task %d\n", task_pid_vnr(task)); |
| } |
| |
| list_for_each_entry(task, &cset->mg_tasks, cg_list) { |
| if (count++ > MAX_TASKS_SHOWN_PER_CSS) |
| goto overflow; |
| seq_printf(seq, " task %d\n", task_pid_vnr(task)); |
| } |
| continue; |
| overflow: |
| seq_puts(seq, " ...\n"); |
| } |
| spin_unlock_irq(&css_set_lock); |
| return 0; |
| } |
| |
| static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft) |
| { |
| return (!cgroup_is_populated(css->cgroup) && |
| !css_has_online_children(&css->cgroup->self)); |
| } |
| |
| static struct cftype debug_files[] = { |
| { |
| .name = "taskcount", |
| .read_u64 = debug_taskcount_read, |
| }, |
| |
| { |
| .name = "current_css_set", |
| .read_u64 = current_css_set_read, |
| }, |
| |
| { |
| .name = "current_css_set_refcount", |
| .read_u64 = current_css_set_refcount_read, |
| }, |
| |
| { |
| .name = "current_css_set_cg_links", |
| .seq_show = current_css_set_cg_links_read, |
| }, |
| |
| { |
| .name = "cgroup_css_links", |
| .seq_show = cgroup_css_links_read, |
| }, |
| |
| { |
| .name = "releasable", |
| .read_u64 = releasable_read, |
| }, |
| |
| { } /* terminate */ |
| }; |
| |
| struct cgroup_subsys debug_cgrp_subsys = { |
| .css_alloc = debug_css_alloc, |
| .css_free = debug_css_free, |
| .legacy_cftypes = debug_files, |
| }; |
| #endif /* CONFIG_CGROUP_DEBUG */ |