| /* |
| * 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. |
| */ |
| |
| #include <linux/cgroup.h> |
| #include <linux/cred.h> |
| #include <linux/ctype.h> |
| #include <linux/errno.h> |
| #include <linux/fs.h> |
| #include <linux/init_task.h> |
| #include <linux/kernel.h> |
| #include <linux/list.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/backing-dev.h> |
| #include <linux/seq_file.h> |
| #include <linux/slab.h> |
| #include <linux/magic.h> |
| #include <linux/spinlock.h> |
| #include <linux/string.h> |
| #include <linux/sort.h> |
| #include <linux/kmod.h> |
| #include <linux/module.h> |
| #include <linux/delayacct.h> |
| #include <linux/cgroupstats.h> |
| #include <linux/hashtable.h> |
| #include <linux/namei.h> |
| #include <linux/pid_namespace.h> |
| #include <linux/idr.h> |
| #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */ |
| #include <linux/eventfd.h> |
| #include <linux/poll.h> |
| #include <linux/flex_array.h> /* used in cgroup_attach_proc */ |
| #include <linux/kthread.h> |
| |
| #include <linux/atomic.h> |
| |
| /* css deactivation bias, makes css->refcnt negative to deny new trygets */ |
| #define CSS_DEACT_BIAS INT_MIN |
| |
| /* |
| * cgroup_mutex is the master lock. Any modification to cgroup or its |
| * hierarchy must be performed while holding it. |
| * |
| * cgroup_root_mutex nests inside cgroup_mutex and should be held to modify |
| * cgroupfs_root of any cgroup hierarchy - subsys list, flags, |
| * release_agent_path and so on. Modifying requires both cgroup_mutex and |
| * cgroup_root_mutex. Readers can acquire either of the two. This is to |
| * break the following locking order cycle. |
| * |
| * A. cgroup_mutex -> cred_guard_mutex -> s_type->i_mutex_key -> namespace_sem |
| * B. namespace_sem -> cgroup_mutex |
| * |
| * B happens only through cgroup_show_options() and using cgroup_root_mutex |
| * breaks it. |
| */ |
| static DEFINE_MUTEX(cgroup_mutex); |
| static DEFINE_MUTEX(cgroup_root_mutex); |
| |
| /* |
| * Generate an array of cgroup subsystem pointers. At boot time, this is |
| * populated with the built in subsystems, and modular subsystems are |
| * registered after that. The mutable section of this array is protected by |
| * cgroup_mutex. |
| */ |
| #define SUBSYS(_x) [_x ## _subsys_id] = &_x ## _subsys, |
| #define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option) |
| static struct cgroup_subsys *subsys[CGROUP_SUBSYS_COUNT] = { |
| #include <linux/cgroup_subsys.h> |
| }; |
| |
| #define MAX_CGROUP_ROOT_NAMELEN 64 |
| |
| /* |
| * A cgroupfs_root represents the root of a cgroup hierarchy, |
| * and may be associated with a superblock to form an active |
| * hierarchy |
| */ |
| struct cgroupfs_root { |
| struct super_block *sb; |
| |
| /* |
| * The bitmask of subsystems intended to be attached to this |
| * hierarchy |
| */ |
| unsigned long subsys_mask; |
| |
| /* Unique id for this hierarchy. */ |
| int hierarchy_id; |
| |
| /* The bitmask of subsystems currently attached to this hierarchy */ |
| unsigned long actual_subsys_mask; |
| |
| /* A list running through the attached subsystems */ |
| struct list_head subsys_list; |
| |
| /* The root cgroup for this hierarchy */ |
| struct cgroup top_cgroup; |
| |
| /* Tracks how many cgroups are currently defined in hierarchy.*/ |
| int number_of_cgroups; |
| |
| /* A list running through the active hierarchies */ |
| struct list_head root_list; |
| |
| /* All cgroups on this root, cgroup_mutex protected */ |
| struct list_head allcg_list; |
| |
| /* Hierarchy-specific flags */ |
| unsigned long flags; |
| |
| /* IDs for cgroups in this hierarchy */ |
| struct ida cgroup_ida; |
| |
| /* The path to use for release notifications. */ |
| char release_agent_path[PATH_MAX]; |
| |
| /* The name for this hierarchy - may be empty */ |
| char name[MAX_CGROUP_ROOT_NAMELEN]; |
| }; |
| |
| /* |
| * The "rootnode" hierarchy is the "dummy 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. |
| */ |
| static struct cgroupfs_root rootnode; |
| |
| /* |
| * cgroupfs file entry, pointed to from leaf dentry->d_fsdata. |
| */ |
| struct cfent { |
| struct list_head node; |
| struct dentry *dentry; |
| struct cftype *type; |
| }; |
| |
| /* |
| * CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when |
| * cgroup_subsys->use_id != 0. |
| */ |
| #define CSS_ID_MAX (65535) |
| struct css_id { |
| /* |
| * The css to which this ID points. This pointer is set to valid value |
| * after cgroup is populated. If cgroup is removed, this will be NULL. |
| * This pointer is expected to be RCU-safe because destroy() |
| * is called after synchronize_rcu(). But for safe use, css_tryget() |
| * should be used for avoiding race. |
| */ |
| struct cgroup_subsys_state __rcu *css; |
| /* |
| * ID of this css. |
| */ |
| unsigned short id; |
| /* |
| * Depth in hierarchy which this ID belongs to. |
| */ |
| unsigned short depth; |
| /* |
| * ID is freed by RCU. (and lookup routine is RCU safe.) |
| */ |
| struct rcu_head rcu_head; |
| /* |
| * Hierarchy of CSS ID belongs to. |
| */ |
| unsigned short stack[0]; /* Array of Length (depth+1) */ |
| }; |
| |
| /* |
| * cgroup_event represents events which userspace want to receive. |
| */ |
| struct cgroup_event { |
| /* |
| * Cgroup which the event belongs to. |
| */ |
| struct cgroup *cgrp; |
| /* |
| * Control file which the event associated. |
| */ |
| struct cftype *cft; |
| /* |
| * eventfd to signal userspace about the event. |
| */ |
| struct eventfd_ctx *eventfd; |
| /* |
| * Each of these stored in a list by the cgroup. |
| */ |
| struct list_head list; |
| /* |
| * All fields below needed to unregister event when |
| * userspace closes eventfd. |
| */ |
| poll_table pt; |
| wait_queue_head_t *wqh; |
| wait_queue_t wait; |
| struct work_struct remove; |
| }; |
| |
| /* The list of hierarchy roots */ |
| |
| static LIST_HEAD(roots); |
| static int root_count; |
| |
| static DEFINE_IDA(hierarchy_ida); |
| static int next_hierarchy_id; |
| static DEFINE_SPINLOCK(hierarchy_id_lock); |
| |
| /* dummytop is a shorthand for the dummy hierarchy's top cgroup */ |
| #define dummytop (&rootnode.top_cgroup) |
| |
| /* This flag indicates whether tasks in the fork and exit paths should |
| * check for fork/exit handlers to call. This avoids us having to do |
| * extra work in the fork/exit path if none of the subsystems need to |
| * be called. |
| */ |
| static int need_forkexit_callback __read_mostly; |
| |
| static int cgroup_destroy_locked(struct cgroup *cgrp); |
| static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys, |
| struct cftype cfts[], bool is_add); |
| |
| #ifdef CONFIG_PROVE_LOCKING |
| int cgroup_lock_is_held(void) |
| { |
| return lockdep_is_held(&cgroup_mutex); |
| } |
| #else /* #ifdef CONFIG_PROVE_LOCKING */ |
| int cgroup_lock_is_held(void) |
| { |
| return mutex_is_locked(&cgroup_mutex); |
| } |
| #endif /* #else #ifdef CONFIG_PROVE_LOCKING */ |
| |
| EXPORT_SYMBOL_GPL(cgroup_lock_is_held); |
| |
| static int css_unbias_refcnt(int refcnt) |
| { |
| return refcnt >= 0 ? refcnt : refcnt - CSS_DEACT_BIAS; |
| } |
| |
| /* the current nr of refs, always >= 0 whether @css is deactivated or not */ |
| static int css_refcnt(struct cgroup_subsys_state *css) |
| { |
| int v = atomic_read(&css->refcnt); |
| |
| return css_unbias_refcnt(v); |
| } |
| |
| /* convenient tests for these bits */ |
| inline int cgroup_is_removed(const struct cgroup *cgrp) |
| { |
| return test_bit(CGRP_REMOVED, &cgrp->flags); |
| } |
| |
| /* bits in struct cgroupfs_root flags field */ |
| enum { |
| ROOT_NOPREFIX, /* mounted subsystems have no named prefix */ |
| ROOT_XATTR, /* supports extended attributes */ |
| }; |
| |
| static int cgroup_is_releasable(const struct cgroup *cgrp) |
| { |
| const int bits = |
| (1 << CGRP_RELEASABLE) | |
| (1 << CGRP_NOTIFY_ON_RELEASE); |
| return (cgrp->flags & bits) == bits; |
| } |
| |
| static int notify_on_release(const struct cgroup *cgrp) |
| { |
| return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
| } |
| |
| /* |
| * for_each_subsys() allows you to iterate on each subsystem attached to |
| * an active hierarchy |
| */ |
| #define for_each_subsys(_root, _ss) \ |
| list_for_each_entry(_ss, &_root->subsys_list, sibling) |
| |
| /* for_each_active_root() allows you to iterate across the active hierarchies */ |
| #define for_each_active_root(_root) \ |
| list_for_each_entry(_root, &roots, root_list) |
| |
| static inline struct cgroup *__d_cgrp(struct dentry *dentry) |
| { |
| return dentry->d_fsdata; |
| } |
| |
| static inline struct cfent *__d_cfe(struct dentry *dentry) |
| { |
| return dentry->d_fsdata; |
| } |
| |
| static inline struct cftype *__d_cft(struct dentry *dentry) |
| { |
| return __d_cfe(dentry)->type; |
| } |
| |
| /* the list of cgroups eligible for automatic release. Protected by |
| * release_list_lock */ |
| static LIST_HEAD(release_list); |
| static DEFINE_RAW_SPINLOCK(release_list_lock); |
| static void cgroup_release_agent(struct work_struct *work); |
| static DECLARE_WORK(release_agent_work, cgroup_release_agent); |
| static void check_for_release(struct cgroup *cgrp); |
| |
| /* Link structure for associating css_set objects with cgroups */ |
| struct cg_cgroup_link { |
| /* |
| * List running through cg_cgroup_links associated with a |
| * cgroup, anchored on cgroup->css_sets |
| */ |
| struct list_head cgrp_link_list; |
| struct cgroup *cgrp; |
| /* |
| * List running through cg_cgroup_links pointing at a |
| * single css_set object, anchored on css_set->cg_links |
| */ |
| struct list_head cg_link_list; |
| struct css_set *cg; |
| }; |
| |
| /* 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. |
| */ |
| |
| static struct css_set init_css_set; |
| static struct cg_cgroup_link init_css_set_link; |
| |
| static int cgroup_init_idr(struct cgroup_subsys *ss, |
| struct cgroup_subsys_state *css); |
| |
| /* css_set_lock protects the list of css_set objects, and the |
| * chain of tasks off each css_set. Nests outside task->alloc_lock |
| * due to cgroup_iter_start() */ |
| static DEFINE_RWLOCK(css_set_lock); |
| static int css_set_count; |
| |
| /* |
| * 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[]) |
| { |
| int i; |
| unsigned long key = 0UL; |
| |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) |
| key += (unsigned long)css[i]; |
| key = (key >> 16) ^ key; |
| |
| return key; |
| } |
| |
| /* We don't maintain the lists running through each css_set to its |
| * task until after the first call to cgroup_iter_start(). This |
| * reduces the fork()/exit() overhead for people who have cgroups |
| * compiled into their kernel but not actually in use */ |
| static int use_task_css_set_links __read_mostly; |
| |
| static void __put_css_set(struct css_set *cg, int taskexit) |
| { |
| struct cg_cgroup_link *link; |
| struct cg_cgroup_link *saved_link; |
| /* |
| * 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(&cg->refcount, -1, 1)) |
| return; |
| write_lock(&css_set_lock); |
| if (!atomic_dec_and_test(&cg->refcount)) { |
| write_unlock(&css_set_lock); |
| return; |
| } |
| |
| /* This css_set is dead. unlink it and release cgroup refcounts */ |
| hash_del(&cg->hlist); |
| css_set_count--; |
| |
| list_for_each_entry_safe(link, saved_link, &cg->cg_links, |
| cg_link_list) { |
| struct cgroup *cgrp = link->cgrp; |
| list_del(&link->cg_link_list); |
| list_del(&link->cgrp_link_list); |
| |
| /* |
| * We may not be holding cgroup_mutex, and if cgrp->count is |
| * dropped to 0 the cgroup can be destroyed at any time, hence |
| * rcu_read_lock is used to keep it alive. |
| */ |
| rcu_read_lock(); |
| if (atomic_dec_and_test(&cgrp->count) && |
| notify_on_release(cgrp)) { |
| if (taskexit) |
| set_bit(CGRP_RELEASABLE, &cgrp->flags); |
| check_for_release(cgrp); |
| } |
| rcu_read_unlock(); |
| |
| kfree(link); |
| } |
| |
| write_unlock(&css_set_lock); |
| kfree_rcu(cg, rcu_head); |
| } |
| |
| /* |
| * refcounted get/put for css_set objects |
| */ |
| static inline void get_css_set(struct css_set *cg) |
| { |
| atomic_inc(&cg->refcount); |
| } |
| |
| static inline void put_css_set(struct css_set *cg) |
| { |
| __put_css_set(cg, 0); |
| } |
| |
| static inline void put_css_set_taskexit(struct css_set *cg) |
| { |
| __put_css_set(cg, 1); |
| } |
| |
| /* |
| * compare_css_sets - helper function for find_existing_css_set(). |
| * @cg: candidate css_set being tested |
| * @old_cg: 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 "cg" matches "old_cg" except for the hierarchy |
| * which "new_cgrp" belongs to, for which it should match "new_cgrp". |
| */ |
| static bool compare_css_sets(struct css_set *cg, |
| struct css_set *old_cg, |
| struct cgroup *new_cgrp, |
| struct cgroup_subsys_state *template[]) |
| { |
| struct list_head *l1, *l2; |
| |
| if (memcmp(template, cg->subsys, sizeof(cg->subsys))) { |
| /* Not all subsystems matched */ |
| return false; |
| } |
| |
| /* |
| * Compare cgroup pointers in order to distinguish between |
| * different cgroups in heirarchies with no subsystems. We |
| * could get by with just this check alone (and skip the |
| * memcmp above) but on most setups the memcmp check will |
| * avoid the need for this more expensive check on almost all |
| * candidates. |
| */ |
| |
| l1 = &cg->cg_links; |
| l2 = &old_cg->cg_links; |
| while (1) { |
| struct cg_cgroup_link *cgl1, *cgl2; |
| struct cgroup *cg1, *cg2; |
| |
| l1 = l1->next; |
| l2 = l2->next; |
| /* See if we reached the end - both lists are equal length. */ |
| if (l1 == &cg->cg_links) { |
| BUG_ON(l2 != &old_cg->cg_links); |
| break; |
| } else { |
| BUG_ON(l2 == &old_cg->cg_links); |
| } |
| /* Locate the cgroups associated with these links. */ |
| cgl1 = list_entry(l1, struct cg_cgroup_link, cg_link_list); |
| cgl2 = list_entry(l2, struct cg_cgroup_link, cg_link_list); |
| cg1 = cgl1->cgrp; |
| cg2 = cgl2->cgrp; |
| /* Hierarchies should be linked in the same order. */ |
| BUG_ON(cg1->root != cg2->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 (cg1->root == new_cgrp->root) { |
| if (cg1 != new_cgrp) |
| return false; |
| } else { |
| if (cg1 != cg2) |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| /* |
| * find_existing_css_set() is a helper for |
| * find_css_set(), and checks to see whether an existing |
| * css_set is suitable. |
| * |
| * oldcg: the cgroup group that we're using before the cgroup |
| * transition |
| * |
| * cgrp: the cgroup that we're moving into |
| * |
| * template: location in which to build the desired set of subsystem |
| * state objects for the new cgroup group |
| */ |
| static struct css_set *find_existing_css_set( |
| struct css_set *oldcg, |
| struct cgroup *cgrp, |
| struct cgroup_subsys_state *template[]) |
| { |
| int i; |
| struct cgroupfs_root *root = cgrp->root; |
| struct css_set *cg; |
| unsigned long key; |
| |
| /* |
| * 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 (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| if (root->subsys_mask & (1UL << i)) { |
| /* Subsystem is in this hierarchy. So we want |
| * the subsystem state from the new |
| * cgroup */ |
| template[i] = cgrp->subsys[i]; |
| } else { |
| /* Subsystem is not in this hierarchy, so we |
| * don't want to change the subsystem state */ |
| template[i] = oldcg->subsys[i]; |
| } |
| } |
| |
| key = css_set_hash(template); |
| hash_for_each_possible(css_set_table, cg, hlist, key) { |
| if (!compare_css_sets(cg, oldcg, cgrp, template)) |
| continue; |
| |
| /* This css_set matches what we need */ |
| return cg; |
| } |
| |
| /* No existing cgroup group matched */ |
| return NULL; |
| } |
| |
| static void free_cg_links(struct list_head *tmp) |
| { |
| struct cg_cgroup_link *link; |
| struct cg_cgroup_link *saved_link; |
| |
| list_for_each_entry_safe(link, saved_link, tmp, cgrp_link_list) { |
| list_del(&link->cgrp_link_list); |
| kfree(link); |
| } |
| } |
| |
| /* |
| * allocate_cg_links() allocates "count" cg_cgroup_link structures |
| * and chains them on tmp through their cgrp_link_list fields. Returns 0 on |
| * success or a negative error |
| */ |
| static int allocate_cg_links(int count, struct list_head *tmp) |
| { |
| struct cg_cgroup_link *link; |
| int i; |
| INIT_LIST_HEAD(tmp); |
| for (i = 0; i < count; i++) { |
| link = kmalloc(sizeof(*link), GFP_KERNEL); |
| if (!link) { |
| free_cg_links(tmp); |
| return -ENOMEM; |
| } |
| list_add(&link->cgrp_link_list, tmp); |
| } |
| return 0; |
| } |
| |
| /** |
| * link_css_set - a helper function to link a css_set to a cgroup |
| * @tmp_cg_links: cg_cgroup_link objects allocated by allocate_cg_links() |
| * @cg: the css_set to be linked |
| * @cgrp: the destination cgroup |
| */ |
| static void link_css_set(struct list_head *tmp_cg_links, |
| struct css_set *cg, struct cgroup *cgrp) |
| { |
| struct cg_cgroup_link *link; |
| |
| BUG_ON(list_empty(tmp_cg_links)); |
| link = list_first_entry(tmp_cg_links, struct cg_cgroup_link, |
| cgrp_link_list); |
| link->cg = cg; |
| link->cgrp = cgrp; |
| atomic_inc(&cgrp->count); |
| list_move(&link->cgrp_link_list, &cgrp->css_sets); |
| /* |
| * Always add links to the tail of the list so that the list |
| * is sorted by order of hierarchy creation |
| */ |
| list_add_tail(&link->cg_link_list, &cg->cg_links); |
| } |
| |
| /* |
| * find_css_set() takes an existing cgroup group and a |
| * cgroup object, and returns a css_set object that's |
| * equivalent to the old group, but with the given cgroup |
| * substituted into the appropriate hierarchy. Must be called with |
| * cgroup_mutex held |
| */ |
| static struct css_set *find_css_set( |
| struct css_set *oldcg, struct cgroup *cgrp) |
| { |
| struct css_set *res; |
| struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT]; |
| |
| struct list_head tmp_cg_links; |
| |
| struct cg_cgroup_link *link; |
| unsigned long key; |
| |
| /* First see if we already have a cgroup group that matches |
| * the desired set */ |
| read_lock(&css_set_lock); |
| res = find_existing_css_set(oldcg, cgrp, template); |
| if (res) |
| get_css_set(res); |
| read_unlock(&css_set_lock); |
| |
| if (res) |
| return res; |
| |
| res = kmalloc(sizeof(*res), GFP_KERNEL); |
| if (!res) |
| return NULL; |
| |
| /* Allocate all the cg_cgroup_link objects that we'll need */ |
| if (allocate_cg_links(root_count, &tmp_cg_links) < 0) { |
| kfree(res); |
| return NULL; |
| } |
| |
| atomic_set(&res->refcount, 1); |
| INIT_LIST_HEAD(&res->cg_links); |
| INIT_LIST_HEAD(&res->tasks); |
| INIT_HLIST_NODE(&res->hlist); |
| |
| /* Copy the set of subsystem state objects generated in |
| * find_existing_css_set() */ |
| memcpy(res->subsys, template, sizeof(res->subsys)); |
| |
| write_lock(&css_set_lock); |
| /* Add reference counts and links from the new css_set. */ |
| list_for_each_entry(link, &oldcg->cg_links, cg_link_list) { |
| struct cgroup *c = link->cgrp; |
| if (c->root == cgrp->root) |
| c = cgrp; |
| link_css_set(&tmp_cg_links, res, c); |
| } |
| |
| BUG_ON(!list_empty(&tmp_cg_links)); |
| |
| css_set_count++; |
| |
| /* Add this cgroup group to the hash table */ |
| key = css_set_hash(res->subsys); |
| hash_add(css_set_table, &res->hlist, key); |
| |
| write_unlock(&css_set_lock); |
| |
| return res; |
| } |
| |
| /* |
| * Return the cgroup for "task" from the given hierarchy. Must be |
| * called with cgroup_mutex held. |
| */ |
| static struct cgroup *task_cgroup_from_root(struct task_struct *task, |
| struct cgroupfs_root *root) |
| { |
| struct css_set *css; |
| struct cgroup *res = NULL; |
| |
| BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
| read_lock(&css_set_lock); |
| /* |
| * 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. |
| */ |
| css = task->cgroups; |
| if (css == &init_css_set) { |
| res = &root->top_cgroup; |
| } else { |
| struct cg_cgroup_link *link; |
| list_for_each_entry(link, &css->cg_links, cg_link_list) { |
| struct cgroup *c = link->cgrp; |
| if (c->root == root) { |
| res = c; |
| break; |
| } |
| } |
| } |
| read_unlock(&css_set_lock); |
| BUG_ON(!res); |
| return res; |
| } |
| |
| /* |
| * There is one global cgroup mutex. We also require taking |
| * task_lock() when dereferencing a task's cgroup subsys pointers. |
| * See "The task_lock() exception", at the end of this comment. |
| * |
| * 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. |
| * |
| * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't |
| * (usually) take cgroup_mutex. These are the two most performance |
| * critical pieces of code here. The exception occurs on cgroup_exit(), |
| * when a task in a notify_on_release cgroup exits. Then cgroup_mutex |
| * is taken, and if the cgroup count is zero, a usermode call made |
| * to the release agent with the name of the cgroup (path relative to |
| * the root of cgroup file system) as the argument. |
| * |
| * 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, top_cgroup |
| * always has either children cgroups and/or using tasks. So we don't |
| * need a special hack to ensure that top_cgroup cannot be deleted. |
| * |
| * The task_lock() exception |
| * |
| * The need for this exception arises from the action of |
| * cgroup_attach_task(), which overwrites one task's cgroup pointer with |
| * another. It does so using cgroup_mutex, however there are |
| * several performance critical places that need to reference |
| * task->cgroup without the expense of grabbing a system global |
| * mutex. Therefore except as noted below, when dereferencing or, as |
| * in cgroup_attach_task(), modifying a task's cgroup pointer we use |
| * task_lock(), which acts on a spinlock (task->alloc_lock) already in |
| * the task_struct routinely used for such matters. |
| * |
| * P.S. One more locking exception. RCU is used to guard the |
| * update of a tasks cgroup pointer by cgroup_attach_task() |
| */ |
| |
| /** |
| * cgroup_lock - lock out any changes to cgroup structures |
| * |
| */ |
| void cgroup_lock(void) |
| { |
| mutex_lock(&cgroup_mutex); |
| } |
| EXPORT_SYMBOL_GPL(cgroup_lock); |
| |
| /** |
| * cgroup_unlock - release lock on cgroup changes |
| * |
| * Undo the lock taken in a previous cgroup_lock() call. |
| */ |
| void cgroup_unlock(void) |
| { |
| mutex_unlock(&cgroup_mutex); |
| } |
| EXPORT_SYMBOL_GPL(cgroup_unlock); |
| |
| /* |
| * A couple of forward declarations required, due to cyclic reference loop: |
| * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir -> |
| * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations |
| * -> cgroup_mkdir. |
| */ |
| |
| static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode); |
| static struct dentry *cgroup_lookup(struct inode *, struct dentry *, unsigned int); |
| static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry); |
| static int cgroup_populate_dir(struct cgroup *cgrp, bool base_files, |
| unsigned long subsys_mask); |
| static const struct inode_operations cgroup_dir_inode_operations; |
| static const struct file_operations proc_cgroupstats_operations; |
| |
| static struct backing_dev_info cgroup_backing_dev_info = { |
| .name = "cgroup", |
| .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, |
| }; |
| |
| static int alloc_css_id(struct cgroup_subsys *ss, |
| struct cgroup *parent, struct cgroup *child); |
| |
| static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb) |
| { |
| struct inode *inode = new_inode(sb); |
| |
| if (inode) { |
| inode->i_ino = get_next_ino(); |
| inode->i_mode = mode; |
| inode->i_uid = current_fsuid(); |
| inode->i_gid = current_fsgid(); |
| inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
| inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info; |
| } |
| return inode; |
| } |
| |
| static void cgroup_free_fn(struct work_struct *work) |
| { |
| struct cgroup *cgrp = container_of(work, struct cgroup, free_work); |
| struct cgroup_subsys *ss; |
| |
| mutex_lock(&cgroup_mutex); |
| /* |
| * Release the subsystem state objects. |
| */ |
| for_each_subsys(cgrp->root, ss) |
| ss->css_free(cgrp); |
| |
| cgrp->root->number_of_cgroups--; |
| mutex_unlock(&cgroup_mutex); |
| |
| /* |
| * Drop the active superblock reference that we took when we |
| * created the cgroup |
| */ |
| deactivate_super(cgrp->root->sb); |
| |
| /* |
| * if we're getting rid of the cgroup, refcount should ensure |
| * that there are no pidlists left. |
| */ |
| BUG_ON(!list_empty(&cgrp->pidlists)); |
| |
| simple_xattrs_free(&cgrp->xattrs); |
| |
| ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id); |
| kfree(cgrp); |
| } |
| |
| static void cgroup_free_rcu(struct rcu_head *head) |
| { |
| struct cgroup *cgrp = container_of(head, struct cgroup, rcu_head); |
| |
| schedule_work(&cgrp->free_work); |
| } |
| |
| static void cgroup_diput(struct dentry *dentry, struct inode *inode) |
| { |
| /* is dentry a directory ? if so, kfree() associated cgroup */ |
| if (S_ISDIR(inode->i_mode)) { |
| struct cgroup *cgrp = dentry->d_fsdata; |
| |
| BUG_ON(!(cgroup_is_removed(cgrp))); |
| call_rcu(&cgrp->rcu_head, cgroup_free_rcu); |
| } else { |
| struct cfent *cfe = __d_cfe(dentry); |
| struct cgroup *cgrp = dentry->d_parent->d_fsdata; |
| struct cftype *cft = cfe->type; |
| |
| WARN_ONCE(!list_empty(&cfe->node) && |
| cgrp != &cgrp->root->top_cgroup, |
| "cfe still linked for %s\n", cfe->type->name); |
| kfree(cfe); |
| simple_xattrs_free(&cft->xattrs); |
| } |
| iput(inode); |
| } |
| |
| static int cgroup_delete(const struct dentry *d) |
| { |
| return 1; |
| } |
| |
| static void remove_dir(struct dentry *d) |
| { |
| struct dentry *parent = dget(d->d_parent); |
| |
| d_delete(d); |
| simple_rmdir(parent->d_inode, d); |
| dput(parent); |
| } |
| |
| static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) |
| { |
| struct cfent *cfe; |
| |
| lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex); |
| lockdep_assert_held(&cgroup_mutex); |
| |
| /* |
| * If we're doing cleanup due to failure of cgroup_create(), |
| * the corresponding @cfe may not exist. |
| */ |
| list_for_each_entry(cfe, &cgrp->files, node) { |
| struct dentry *d = cfe->dentry; |
| |
| if (cft && cfe->type != cft) |
| continue; |
| |
| dget(d); |
| d_delete(d); |
| simple_unlink(cgrp->dentry->d_inode, d); |
| list_del_init(&cfe->node); |
| dput(d); |
| |
| break; |
| } |
| } |
| |
| /** |
| * cgroup_clear_directory - selective removal of base and subsystem files |
| * @dir: directory containing the files |
| * @base_files: true if the base files should be removed |
| * @subsys_mask: mask of the subsystem ids whose files should be removed |
| */ |
| static void cgroup_clear_directory(struct dentry *dir, bool base_files, |
| unsigned long subsys_mask) |
| { |
| struct cgroup *cgrp = __d_cgrp(dir); |
| struct cgroup_subsys *ss; |
| |
| for_each_subsys(cgrp->root, ss) { |
| struct cftype_set *set; |
| if (!test_bit(ss->subsys_id, &subsys_mask)) |
| continue; |
| list_for_each_entry(set, &ss->cftsets, node) |
| cgroup_addrm_files(cgrp, NULL, set->cfts, false); |
| } |
| if (base_files) { |
| while (!list_empty(&cgrp->files)) |
| cgroup_rm_file(cgrp, NULL); |
| } |
| } |
| |
| /* |
| * NOTE : the dentry must have been dget()'ed |
| */ |
| static void cgroup_d_remove_dir(struct dentry *dentry) |
| { |
| struct dentry *parent; |
| struct cgroupfs_root *root = dentry->d_sb->s_fs_info; |
| |
| cgroup_clear_directory(dentry, true, root->subsys_mask); |
| |
| parent = dentry->d_parent; |
| spin_lock(&parent->d_lock); |
| spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
| list_del_init(&dentry->d_u.d_child); |
| spin_unlock(&dentry->d_lock); |
| spin_unlock(&parent->d_lock); |
| remove_dir(dentry); |
| } |
| |
| /* |
| * Call with cgroup_mutex held. Drops reference counts on modules, including |
| * any duplicate ones that parse_cgroupfs_options took. If this function |
| * returns an error, no reference counts are touched. |
| */ |
| static int rebind_subsystems(struct cgroupfs_root *root, |
| unsigned long final_subsys_mask) |
| { |
| unsigned long added_mask, removed_mask; |
| struct cgroup *cgrp = &root->top_cgroup; |
| int i; |
| |
| BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
| BUG_ON(!mutex_is_locked(&cgroup_root_mutex)); |
| |
| removed_mask = root->actual_subsys_mask & ~final_subsys_mask; |
| added_mask = final_subsys_mask & ~root->actual_subsys_mask; |
| /* Check that any added subsystems are currently free */ |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| unsigned long bit = 1UL << i; |
| struct cgroup_subsys *ss = subsys[i]; |
| if (!(bit & added_mask)) |
| continue; |
| /* |
| * Nobody should tell us to do a subsys that doesn't exist: |
| * parse_cgroupfs_options should catch that case and refcounts |
| * ensure that subsystems won't disappear once selected. |
| */ |
| BUG_ON(ss == NULL); |
| if (ss->root != &rootnode) { |
| /* Subsystem isn't free */ |
| return -EBUSY; |
| } |
| } |
| |
| /* Currently we don't handle adding/removing subsystems when |
| * any child cgroups exist. This is theoretically supportable |
| * but involves complex error handling, so it's being left until |
| * later */ |
| if (root->number_of_cgroups > 1) |
| return -EBUSY; |
| |
| /* Process each subsystem */ |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| struct cgroup_subsys *ss = subsys[i]; |
| unsigned long bit = 1UL << i; |
| if (bit & added_mask) { |
| /* We're binding this subsystem to this hierarchy */ |
| BUG_ON(ss == NULL); |
| BUG_ON(cgrp->subsys[i]); |
| BUG_ON(!dummytop->subsys[i]); |
| BUG_ON(dummytop->subsys[i]->cgroup != dummytop); |
| cgrp->subsys[i] = dummytop->subsys[i]; |
| cgrp->subsys[i]->cgroup = cgrp; |
| list_move(&ss->sibling, &root->subsys_list); |
| ss->root = root; |
| if (ss->bind) |
| ss->bind(cgrp); |
| /* refcount was already taken, and we're keeping it */ |
| } else if (bit & removed_mask) { |
| /* We're removing this subsystem */ |
| BUG_ON(ss == NULL); |
| BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]); |
| BUG_ON(cgrp->subsys[i]->cgroup != cgrp); |
| if (ss->bind) |
| ss->bind(dummytop); |
| dummytop->subsys[i]->cgroup = dummytop; |
| cgrp->subsys[i] = NULL; |
| subsys[i]->root = &rootnode; |
| list_move(&ss->sibling, &rootnode.subsys_list); |
| /* subsystem is now free - drop reference on module */ |
| module_put(ss->module); |
| } else if (bit & final_subsys_mask) { |
| /* Subsystem state should already exist */ |
| BUG_ON(ss == NULL); |
| BUG_ON(!cgrp->subsys[i]); |
| /* |
| * a refcount was taken, but we already had one, so |
| * drop the extra reference. |
| */ |
| module_put(ss->module); |
| #ifdef CONFIG_MODULE_UNLOAD |
| BUG_ON(ss->module && !module_refcount(ss->module)); |
| #endif |
| } else { |
| /* Subsystem state shouldn't exist */ |
| BUG_ON(cgrp->subsys[i]); |
| } |
| } |
| root->subsys_mask = root->actual_subsys_mask = final_subsys_mask; |
| |
| return 0; |
| } |
| |
| static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry) |
| { |
| struct cgroupfs_root *root = dentry->d_sb->s_fs_info; |
| struct cgroup_subsys *ss; |
| |
| mutex_lock(&cgroup_root_mutex); |
| for_each_subsys(root, ss) |
| seq_printf(seq, ",%s", ss->name); |
| if (test_bit(ROOT_NOPREFIX, &root->flags)) |
| seq_puts(seq, ",noprefix"); |
| if (test_bit(ROOT_XATTR, &root->flags)) |
| seq_puts(seq, ",xattr"); |
| if (strlen(root->release_agent_path)) |
| seq_printf(seq, ",release_agent=%s", root->release_agent_path); |
| if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->top_cgroup.flags)) |
| seq_puts(seq, ",clone_children"); |
| if (strlen(root->name)) |
| seq_printf(seq, ",name=%s", root->name); |
| mutex_unlock(&cgroup_root_mutex); |
| return 0; |
| } |
| |
| struct cgroup_sb_opts { |
| unsigned long subsys_mask; |
| unsigned long flags; |
| char *release_agent; |
| bool cpuset_clone_children; |
| char *name; |
| /* User explicitly requested empty subsystem */ |
| bool none; |
| |
| struct cgroupfs_root *new_root; |
| |
| }; |
| |
| /* |
| * Convert a hierarchy specifier into a bitmask of subsystems and flags. Call |
| * with cgroup_mutex held to protect the subsys[] array. This function takes |
| * refcounts on subsystems to be used, unless it returns error, in which case |
| * no refcounts are taken. |
| */ |
| static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) |
| { |
| char *token, *o = data; |
| bool all_ss = false, one_ss = false; |
| unsigned long mask = (unsigned long)-1; |
| int i; |
| bool module_pin_failed = false; |
| |
| BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
| |
| #ifdef CONFIG_CPUSETS |
| mask = ~(1UL << cpuset_subsys_id); |
| #endif |
| |
| memset(opts, 0, sizeof(*opts)); |
| |
| while ((token = strsep(&o, ",")) != NULL) { |
| 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")) { |
| set_bit(ROOT_NOPREFIX, &opts->flags); |
| continue; |
| } |
| if (!strcmp(token, "clone_children")) { |
| opts->cpuset_clone_children = true; |
| continue; |
| } |
| if (!strcmp(token, "xattr")) { |
| set_bit(ROOT_XATTR, &opts->flags); |
| 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 (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| struct cgroup_subsys *ss = subsys[i]; |
| if (ss == NULL) |
| continue; |
| if (strcmp(token, ss->name)) |
| continue; |
| if (ss->disabled) |
| continue; |
| |
| /* Mutually exclusive option 'all' + subsystem name */ |
| if (all_ss) |
| return -EINVAL; |
| set_bit(i, &opts->subsys_mask); |
| 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 (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| struct cgroup_subsys *ss = subsys[i]; |
| if (ss == NULL) |
| continue; |
| if (ss->disabled) |
| continue; |
| set_bit(i, &opts->subsys_mask); |
| } |
| } |
| |
| /* Consistency checks */ |
| |
| /* |
| * Option noprefix was introduced just for backward compatibility |
| * with the old cpuset, so we allow noprefix only if mounting just |
| * the cpuset subsystem. |
| */ |
| if (test_bit(ROOT_NOPREFIX, &opts->flags) && |
| (opts->subsys_mask & mask)) |
| return -EINVAL; |
| |
| |
| /* Can't specify "none" and some subsystems */ |
| if (opts->subsys_mask && opts->none) |
| return -EINVAL; |
| |
| /* |
| * 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; |
| |
| /* |
| * Grab references on all the modules we'll need, so the subsystems |
| * don't dance around before rebind_subsystems attaches them. This may |
| * take duplicate reference counts on a subsystem that's already used, |
| * but rebind_subsystems handles this case. |
| */ |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| unsigned long bit = 1UL << i; |
| |
| if (!(bit & opts->subsys_mask)) |
| continue; |
| if (!try_module_get(subsys[i]->module)) { |
| module_pin_failed = true; |
| break; |
| } |
| } |
| if (module_pin_failed) { |
| /* |
| * oops, one of the modules was going away. this means that we |
| * raced with a module_delete call, and to the user this is |
| * essentially a "subsystem doesn't exist" case. |
| */ |
| for (i--; i >= 0; i--) { |
| /* drop refcounts only on the ones we took */ |
| unsigned long bit = 1UL << i; |
| |
| if (!(bit & opts->subsys_mask)) |
| continue; |
| module_put(subsys[i]->module); |
| } |
| return -ENOENT; |
| } |
| |
| return 0; |
| } |
| |
| static void drop_parsed_module_refcounts(unsigned long subsys_mask) |
| { |
| int i; |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| unsigned long bit = 1UL << i; |
| |
| if (!(bit & subsys_mask)) |
| continue; |
| module_put(subsys[i]->module); |
| } |
| } |
| |
| static int cgroup_remount(struct super_block *sb, int *flags, char *data) |
| { |
| int ret = 0; |
| struct cgroupfs_root *root = sb->s_fs_info; |
| struct cgroup *cgrp = &root->top_cgroup; |
| struct cgroup_sb_opts opts; |
| unsigned long added_mask, removed_mask; |
| |
| mutex_lock(&cgrp->dentry->d_inode->i_mutex); |
| mutex_lock(&cgroup_mutex); |
| mutex_lock(&cgroup_root_mutex); |
| |
| /* See what subsystems are wanted */ |
| ret = parse_cgroupfs_options(data, &opts); |
| if (ret) |
| goto out_unlock; |
| |
| if (opts.subsys_mask != root->actual_subsys_mask || opts.release_agent) |
| pr_warning("cgroup: 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))) { |
| ret = -EINVAL; |
| drop_parsed_module_refcounts(opts.subsys_mask); |
| goto out_unlock; |
| } |
| |
| /* |
| * Clear out the files of subsystems that should be removed, do |
| * this before rebind_subsystems, since rebind_subsystems may |
| * change this hierarchy's subsys_list. |
| */ |
| cgroup_clear_directory(cgrp->dentry, false, removed_mask); |
| |
| ret = rebind_subsystems(root, opts.subsys_mask); |
| if (ret) { |
| /* rebind_subsystems failed, re-populate the removed files */ |
| cgroup_populate_dir(cgrp, false, removed_mask); |
| drop_parsed_module_refcounts(opts.subsys_mask); |
| goto out_unlock; |
| } |
| |
| /* re-populate subsystem files */ |
| cgroup_populate_dir(cgrp, false, added_mask); |
| |
| if (opts.release_agent) |
| strcpy(root->release_agent_path, opts.release_agent); |
| out_unlock: |
| kfree(opts.release_agent); |
| kfree(opts.name); |
| mutex_unlock(&cgroup_root_mutex); |
| mutex_unlock(&cgroup_mutex); |
| mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
| return ret; |
| } |
| |
| static const struct super_operations cgroup_ops = { |
| .statfs = simple_statfs, |
| .drop_inode = generic_delete_inode, |
| .show_options = cgroup_show_options, |
| .remount_fs = cgroup_remount, |
| }; |
| |
| static void init_cgroup_housekeeping(struct cgroup *cgrp) |
| { |
| INIT_LIST_HEAD(&cgrp->sibling); |
| INIT_LIST_HEAD(&cgrp->children); |
| INIT_LIST_HEAD(&cgrp->files); |
| INIT_LIST_HEAD(&cgrp->css_sets); |
| INIT_LIST_HEAD(&cgrp->allcg_node); |
| INIT_LIST_HEAD(&cgrp->release_list); |
| INIT_LIST_HEAD(&cgrp->pidlists); |
| INIT_WORK(&cgrp->free_work, cgroup_free_fn); |
| mutex_init(&cgrp->pidlist_mutex); |
| INIT_LIST_HEAD(&cgrp->event_list); |
| spin_lock_init(&cgrp->event_list_lock); |
| simple_xattrs_init(&cgrp->xattrs); |
| } |
| |
| static void init_cgroup_root(struct cgroupfs_root *root) |
| { |
| struct cgroup *cgrp = &root->top_cgroup; |
| |
| INIT_LIST_HEAD(&root->subsys_list); |
| INIT_LIST_HEAD(&root->root_list); |
| INIT_LIST_HEAD(&root->allcg_list); |
| root->number_of_cgroups = 1; |
| cgrp->root = root; |
| cgrp->top_cgroup = cgrp; |
| init_cgroup_housekeeping(cgrp); |
| list_add_tail(&cgrp->allcg_node, &root->allcg_list); |
| } |
| |
| static bool init_root_id(struct cgroupfs_root *root) |
| { |
| int ret = 0; |
| |
| do { |
| if (!ida_pre_get(&hierarchy_ida, GFP_KERNEL)) |
| return false; |
| spin_lock(&hierarchy_id_lock); |
| /* Try to allocate the next unused ID */ |
| ret = ida_get_new_above(&hierarchy_ida, next_hierarchy_id, |
| &root->hierarchy_id); |
| if (ret == -ENOSPC) |
| /* Try again starting from 0 */ |
| ret = ida_get_new(&hierarchy_ida, &root->hierarchy_id); |
| if (!ret) { |
| next_hierarchy_id = root->hierarchy_id + 1; |
| } else if (ret != -EAGAIN) { |
| /* Can only get here if the 31-bit IDR is full ... */ |
| BUG_ON(ret); |
| } |
| spin_unlock(&hierarchy_id_lock); |
| } while (ret); |
| return true; |
| } |
| |
| static int cgroup_test_super(struct super_block *sb, void *data) |
| { |
| struct cgroup_sb_opts *opts = data; |
| struct cgroupfs_root *root = sb->s_fs_info; |
| |
| /* If we asked for a name then it must match */ |
| if (opts->name && strcmp(opts->name, root->name)) |
| return 0; |
| |
| /* |
| * 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)) |
| return 0; |
| |
| return 1; |
| } |
| |
| static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) |
| { |
| struct cgroupfs_root *root; |
| |
| if (!opts->subsys_mask && !opts->none) |
| return NULL; |
| |
| root = kzalloc(sizeof(*root), GFP_KERNEL); |
| if (!root) |
| return ERR_PTR(-ENOMEM); |
| |
| if (!init_root_id(root)) { |
| kfree(root); |
| return ERR_PTR(-ENOMEM); |
| } |
| init_cgroup_root(root); |
| |
| root->subsys_mask = opts->subsys_mask; |
| root->flags = opts->flags; |
| ida_init(&root->cgroup_ida); |
| 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->top_cgroup.flags); |
| return root; |
| } |
| |
| static void cgroup_drop_root(struct cgroupfs_root *root) |
| { |
| if (!root) |
| return; |
| |
| BUG_ON(!root->hierarchy_id); |
| spin_lock(&hierarchy_id_lock); |
| ida_remove(&hierarchy_ida, root->hierarchy_id); |
| spin_unlock(&hierarchy_id_lock); |
| ida_destroy(&root->cgroup_ida); |
| kfree(root); |
| } |
| |
| static int cgroup_set_super(struct super_block *sb, void *data) |
| { |
| int ret; |
| struct cgroup_sb_opts *opts = data; |
| |
| /* If we don't have a new root, we can't set up a new sb */ |
| if (!opts->new_root) |
| return -EINVAL; |
| |
| BUG_ON(!opts->subsys_mask && !opts->none); |
| |
| ret = set_anon_super(sb, NULL); |
| if (ret) |
| return ret; |
| |
| sb->s_fs_info = opts->new_root; |
| opts->new_root->sb = sb; |
| |
| sb->s_blocksize = PAGE_CACHE_SIZE; |
| sb->s_blocksize_bits = PAGE_CACHE_SHIFT; |
| sb->s_magic = CGROUP_SUPER_MAGIC; |
| sb->s_op = &cgroup_ops; |
| |
| return 0; |
| } |
| |
| static int cgroup_get_rootdir(struct super_block *sb) |
| { |
| static const struct dentry_operations cgroup_dops = { |
| .d_iput = cgroup_diput, |
| .d_delete = cgroup_delete, |
| }; |
| |
| struct inode *inode = |
| cgroup_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR, sb); |
| |
| if (!inode) |
| return -ENOMEM; |
| |
| inode->i_fop = &simple_dir_operations; |
| inode->i_op = &cgroup_dir_inode_operations; |
| /* directories start off with i_nlink == 2 (for "." entry) */ |
| inc_nlink(inode); |
| sb->s_root = d_make_root(inode); |
| if (!sb->s_root) |
| return -ENOMEM; |
| /* for everything else we want ->d_op set */ |
| sb->s_d_op = &cgroup_dops; |
| return 0; |
| } |
| |
| static struct dentry *cgroup_mount(struct file_system_type *fs_type, |
| int flags, const char *unused_dev_name, |
| void *data) |
| { |
| struct cgroup_sb_opts opts; |
| struct cgroupfs_root *root; |
| int ret = 0; |
| struct super_block *sb; |
| struct cgroupfs_root *new_root; |
| struct inode *inode; |
| |
| /* First find the desired set of subsystems */ |
| mutex_lock(&cgroup_mutex); |
| ret = parse_cgroupfs_options(data, &opts); |
| mutex_unlock(&cgroup_mutex); |
| if (ret) |
| goto out_err; |
| |
| /* |
| * Allocate a new cgroup root. We may not need it if we're |
| * reusing an existing hierarchy. |
| */ |
| new_root = cgroup_root_from_opts(&opts); |
| if (IS_ERR(new_root)) { |
| ret = PTR_ERR(new_root); |
| goto drop_modules; |
| } |
| opts.new_root = new_root; |
| |
| /* Locate an existing or new sb for this hierarchy */ |
| sb = sget(fs_type, cgroup_test_super, cgroup_set_super, 0, &opts); |
| if (IS_ERR(sb)) { |
| ret = PTR_ERR(sb); |
| cgroup_drop_root(opts.new_root); |
| goto drop_modules; |
| } |
| |
| root = sb->s_fs_info; |
| BUG_ON(!root); |
| if (root == opts.new_root) { |
| /* We used the new root structure, so this is a new hierarchy */ |
| struct list_head tmp_cg_links; |
| struct cgroup *root_cgrp = &root->top_cgroup; |
| struct cgroupfs_root *existing_root; |
| const struct cred *cred; |
| int i; |
| struct css_set *cg; |
| |
| BUG_ON(sb->s_root != NULL); |
| |
| ret = cgroup_get_rootdir(sb); |
| if (ret) |
| goto drop_new_super; |
| inode = sb->s_root->d_inode; |
| |
| mutex_lock(&inode->i_mutex); |
| mutex_lock(&cgroup_mutex); |
| mutex_lock(&cgroup_root_mutex); |
| |
| /* Check for name clashes with existing mounts */ |
| ret = -EBUSY; |
| if (strlen(root->name)) |
| for_each_active_root(existing_root) |
| if (!strcmp(existing_root->name, root->name)) |
| goto unlock_drop; |
| |
| /* |
| * 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. The worst that can happen is that we |
| * have some link structures left over |
| */ |
| ret = allocate_cg_links(css_set_count, &tmp_cg_links); |
| if (ret) |
| goto unlock_drop; |
| |
| ret = rebind_subsystems(root, root->subsys_mask); |
| if (ret == -EBUSY) { |
| free_cg_links(&tmp_cg_links); |
| goto unlock_drop; |
| } |
| /* |
| * There must be no failure case after here, since rebinding |
| * takes care of subsystems' refcounts, which are explicitly |
| * dropped in the failure exit path. |
| */ |
| |
| /* EBUSY should be the only error here */ |
| BUG_ON(ret); |
| |
| list_add(&root->root_list, &roots); |
| root_count++; |
| |
| sb->s_root->d_fsdata = root_cgrp; |
| root->top_cgroup.dentry = sb->s_root; |
| |
| /* Link the top cgroup in this hierarchy into all |
| * the css_set objects */ |
| write_lock(&css_set_lock); |
| hash_for_each(css_set_table, i, cg, hlist) |
| link_css_set(&tmp_cg_links, cg, root_cgrp); |
| write_unlock(&css_set_lock); |
| |
| free_cg_links(&tmp_cg_links); |
| |
| BUG_ON(!list_empty(&root_cgrp->children)); |
| BUG_ON(root->number_of_cgroups != 1); |
| |
| cred = override_creds(&init_cred); |
| cgroup_populate_dir(root_cgrp, true, root->subsys_mask); |
| revert_creds(cred); |
| mutex_unlock(&cgroup_root_mutex); |
| mutex_unlock(&cgroup_mutex); |
| mutex_unlock(&inode->i_mutex); |
| } else { |
| /* |
| * We re-used an existing hierarchy - the new root (if |
| * any) is not needed |
| */ |
| cgroup_drop_root(opts.new_root); |
| /* no subsys rebinding, so refcounts don't change */ |
| drop_parsed_module_refcounts(opts.subsys_mask); |
| } |
| |
| kfree(opts.release_agent); |
| kfree(opts.name); |
| return dget(sb->s_root); |
| |
| unlock_drop: |
| mutex_unlock(&cgroup_root_mutex); |
| mutex_unlock(&cgroup_mutex); |
| mutex_unlock(&inode->i_mutex); |
| drop_new_super: |
| deactivate_locked_super(sb); |
| drop_modules: |
| drop_parsed_module_refcounts(opts.subsys_mask); |
| out_err: |
| kfree(opts.release_agent); |
| kfree(opts.name); |
| return ERR_PTR(ret); |
| } |
| |
| static void cgroup_kill_sb(struct super_block *sb) { |
| struct cgroupfs_root *root = sb->s_fs_info; |
| struct cgroup *cgrp = &root->top_cgroup; |
| int ret; |
| struct cg_cgroup_link *link; |
| struct cg_cgroup_link *saved_link; |
| |
| BUG_ON(!root); |
| |
| BUG_ON(root->number_of_cgroups != 1); |
| BUG_ON(!list_empty(&cgrp->children)); |
| |
| mutex_lock(&cgroup_mutex); |
| mutex_lock(&cgroup_root_mutex); |
| |
| /* Rebind all subsystems back to the default hierarchy */ |
| ret = rebind_subsystems(root, 0); |
| /* Shouldn't be able to fail ... */ |
| BUG_ON(ret); |
| |
| /* |
| * Release all the links from css_sets to this hierarchy's |
| * root cgroup |
| */ |
| write_lock(&css_set_lock); |
| |
| list_for_each_entry_safe(link, saved_link, &cgrp->css_sets, |
| cgrp_link_list) { |
| list_del(&link->cg_link_list); |
| list_del(&link->cgrp_link_list); |
| kfree(link); |
| } |
| write_unlock(&css_set_lock); |
| |
| if (!list_empty(&root->root_list)) { |
| list_del(&root->root_list); |
| root_count--; |
| } |
| |
| mutex_unlock(&cgroup_root_mutex); |
| mutex_unlock(&cgroup_mutex); |
| |
| simple_xattrs_free(&cgrp->xattrs); |
| |
| kill_litter_super(sb); |
| cgroup_drop_root(root); |
| } |
| |
| static struct file_system_type cgroup_fs_type = { |
| .name = "cgroup", |
| .mount = cgroup_mount, |
| .kill_sb = cgroup_kill_sb, |
| }; |
| |
| static struct kobject *cgroup_kobj; |
| |
| /** |
| * cgroup_path - generate the path of a cgroup |
| * @cgrp: the cgroup in question |
| * @buf: the buffer to write the path into |
| * @buflen: the length of the buffer |
| * |
| * Called with cgroup_mutex held or else with an RCU-protected cgroup |
| * reference. Writes path of cgroup into buf. Returns 0 on success, |
| * -errno on error. |
| */ |
| int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) |
| { |
| struct dentry *dentry = cgrp->dentry; |
| char *start; |
| |
| rcu_lockdep_assert(rcu_read_lock_held() || cgroup_lock_is_held(), |
| "cgroup_path() called without proper locking"); |
| |
| if (cgrp == dummytop) { |
| /* |
| * Inactive subsystems have no dentry for their root |
| * cgroup |
| */ |
| strcpy(buf, "/"); |
| return 0; |
| } |
| |
| start = buf + buflen - 1; |
| |
| *start = '\0'; |
| for (;;) { |
| int len = dentry->d_name.len; |
| |
| if ((start -= len) < buf) |
| return -ENAMETOOLONG; |
| memcpy(start, dentry->d_name.name, len); |
| cgrp = cgrp->parent; |
| if (!cgrp) |
| break; |
| |
| dentry = cgrp->dentry; |
| if (!cgrp->parent) |
| continue; |
| if (--start < buf) |
| return -ENAMETOOLONG; |
| *start = '/'; |
| } |
| memmove(buf, start, buf + buflen - start); |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(cgroup_path); |
| |
| /* |
| * Control Group taskset |
| */ |
| struct task_and_cgroup { |
| struct task_struct *task; |
| struct cgroup *cgrp; |
| struct css_set *cg; |
| }; |
| |
| struct cgroup_taskset { |
| struct task_and_cgroup single; |
| struct flex_array *tc_array; |
| int tc_array_len; |
| int idx; |
| struct cgroup *cur_cgrp; |
| }; |
| |
| /** |
| * cgroup_taskset_first - reset taskset and return the first task |
| * @tset: taskset of interest |
| * |
| * @tset iteration is initialized and the first task is returned. |
| */ |
| struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset) |
| { |
| if (tset->tc_array) { |
| tset->idx = 0; |
| return cgroup_taskset_next(tset); |
| } else { |
| tset->cur_cgrp = tset->single.cgrp; |
| return tset->single.task; |
| } |
| } |
| EXPORT_SYMBOL_GPL(cgroup_taskset_first); |
| |
| /** |
| * cgroup_taskset_next - iterate to the next task in taskset |
| * @tset: taskset of interest |
| * |
| * 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 task_and_cgroup *tc; |
| |
| if (!tset->tc_array || tset->idx >= tset->tc_array_len) |
| return NULL; |
| |
| tc = flex_array_get(tset->tc_array, tset->idx++); |
| tset->cur_cgrp = tc->cgrp; |
| return tc->task; |
| } |
| EXPORT_SYMBOL_GPL(cgroup_taskset_next); |
| |
| /** |
| * cgroup_taskset_cur_cgroup - return the matching cgroup for the current task |
| * @tset: taskset of interest |
| * |
| * Return the cgroup for the current (last returned) task of @tset. This |
| * function must be preceded by either cgroup_taskset_first() or |
| * cgroup_taskset_next(). |
| */ |
| struct cgroup *cgroup_taskset_cur_cgroup(struct cgroup_taskset *tset) |
| { |
| return tset->cur_cgrp; |
| } |
| EXPORT_SYMBOL_GPL(cgroup_taskset_cur_cgroup); |
| |
| /** |
| * cgroup_taskset_size - return the number of tasks in taskset |
| * @tset: taskset of interest |
| */ |
| int cgroup_taskset_size(struct cgroup_taskset *tset) |
| { |
| return tset->tc_array ? tset->tc_array_len : 1; |
| } |
| EXPORT_SYMBOL_GPL(cgroup_taskset_size); |
| |
| |
| /* |
| * cgroup_task_migrate - move a task from one cgroup to another. |
| * |
| * Must be called with cgroup_mutex and threadgroup locked. |
| */ |
| static void cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp, |
| struct task_struct *tsk, struct css_set *newcg) |
| { |
| struct css_set *oldcg; |
| |
| /* |
| * We are synchronized through threadgroup_lock() 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(tsk->flags & PF_EXITING); |
| oldcg = tsk->cgroups; |
| |
| task_lock(tsk); |
| rcu_assign_pointer(tsk->cgroups, newcg); |
| task_unlock(tsk); |
| |
| /* Update the css_set linked lists if we're using them */ |
| write_lock(&css_set_lock); |
| if (!list_empty(&tsk->cg_list)) |
| list_move(&tsk->cg_list, &newcg->tasks); |
| write_unlock(&css_set_lock); |
| |
| /* |
| * We just gained a reference on oldcg by taking it from the task. As |
| * trading it for newcg is protected by cgroup_mutex, we're safe to drop |
| * it here; it will be freed under RCU. |
| */ |
| set_bit(CGRP_RELEASABLE, &oldcgrp->flags); |
| put_css_set(oldcg); |
| } |
| |
| /** |
| * cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp' |
| * @cgrp: the cgroup the task is attaching to |
| * @tsk: the task to be attached |
| * |
| * Call with cgroup_mutex and threadgroup locked. May take task_lock of |
| * @tsk during call. |
| */ |
| int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) |
| { |
| int retval = 0; |
| struct cgroup_subsys *ss, *failed_ss = NULL; |
| struct cgroup *oldcgrp; |
| struct cgroupfs_root *root = cgrp->root; |
| struct cgroup_taskset tset = { }; |
| struct css_set *newcg; |
| |
| /* @tsk either already exited or can't exit until the end */ |
| if (tsk->flags & PF_EXITING) |
| return -ESRCH; |
| |
| /* Nothing to do if the task is already in that cgroup */ |
| oldcgrp = task_cgroup_from_root(tsk, root); |
| if (cgrp == oldcgrp) |
| return 0; |
| |
| tset.single.task = tsk; |
| tset.single.cgrp = oldcgrp; |
| |
| for_each_subsys(root, ss) { |
| if (ss->can_attach) { |
| retval = ss->can_attach(cgrp, &tset); |
| if (retval) { |
| /* |
| * Remember on which subsystem the can_attach() |
| * failed, so that we only call cancel_attach() |
| * against the subsystems whose can_attach() |
| * succeeded. (See below) |
| */ |
| failed_ss = ss; |
| goto out; |
| } |
| } |
| } |
| |
| newcg = find_css_set(tsk->cgroups, cgrp); |
| if (!newcg) { |
| retval = -ENOMEM; |
| goto out; |
| } |
| |
| cgroup_task_migrate(cgrp, oldcgrp, tsk, newcg); |
| |
| for_each_subsys(root, ss) { |
| if (ss->attach) |
| ss->attach(cgrp, &tset); |
| } |
| |
| out: |
| if (retval) { |
| for_each_subsys(root, ss) { |
| if (ss == failed_ss) |
| /* |
| * This subsystem was the one that failed the |
| * can_attach() check earlier, so we don't need |
| * to call cancel_attach() against it or any |
| * remaining subsystems. |
| */ |
| break; |
| if (ss->cancel_attach) |
| ss->cancel_attach(cgrp, &tset); |
| } |
| } |
| return retval; |
| } |
| |
| /** |
| * 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 cgroupfs_root *root; |
| int retval = 0; |
| |
| cgroup_lock(); |
| for_each_active_root(root) { |
| struct cgroup *from_cg = task_cgroup_from_root(from, root); |
| |
| retval = cgroup_attach_task(from_cg, tsk); |
| if (retval) |
| break; |
| } |
| cgroup_unlock(); |
| |
| return retval; |
| } |
| EXPORT_SYMBOL_GPL(cgroup_attach_task_all); |
| |
| /** |
| * cgroup_attach_proc - attach all threads in a threadgroup to a cgroup |
| * @cgrp: the cgroup to attach to |
| * @leader: the threadgroup leader task_struct of the group to be attached |
| * |
| * Call holding cgroup_mutex and the group_rwsem of the leader. Will take |
| * task_lock of each thread in leader's threadgroup individually in turn. |
| */ |
| static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) |
| { |
| int retval, i, group_size; |
| struct cgroup_subsys *ss, *failed_ss = NULL; |
| /* guaranteed to be initialized later, but the compiler needs this */ |
| struct cgroupfs_root *root = cgrp->root; |
| /* threadgroup list cursor and array */ |
| struct task_struct *tsk; |
| struct task_and_cgroup *tc; |
| struct flex_array *group; |
| struct cgroup_taskset tset = { }; |
| |
| /* |
| * step 0: in order to do expensive, possibly blocking operations for |
| * every thread, we cannot iterate the thread group list, since it needs |
| * rcu or tasklist locked. instead, build an array of all threads in the |
| * group - group_rwsem prevents new threads from appearing, and if |
| * threads exit, this will just be an over-estimate. |
| */ |
| group_size = get_nr_threads(leader); |
| /* flex_array supports very large thread-groups better than kmalloc. */ |
| group = flex_array_alloc(sizeof(*tc), group_size, GFP_KERNEL); |
| if (!group) |
| return -ENOMEM; |
| /* pre-allocate to guarantee space while iterating in rcu read-side. */ |
| retval = flex_array_prealloc(group, 0, group_size - 1, GFP_KERNEL); |
| if (retval) |
| goto out_free_group_list; |
| |
| tsk = leader; |
| i = 0; |
| /* |
| * 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. |
| */ |
| rcu_read_lock(); |
| do { |
| struct task_and_cgroup ent; |
| |
| /* @tsk either already exited or can't exit until the end */ |
| if (tsk->flags & PF_EXITING) |
| continue; |
| |
| /* as per above, nr_threads may decrease, but not increase. */ |
| BUG_ON(i >= group_size); |
| ent.task = tsk; |
| ent.cgrp = task_cgroup_from_root(tsk, root); |
| /* nothing to do if this task is already in the cgroup */ |
| if (ent.cgrp == cgrp) |
| continue; |
| /* |
| * saying GFP_ATOMIC has no effect here because we did prealloc |
| * earlier, but it's good form to communicate our expectations. |
| */ |
| retval = flex_array_put(group, i, &ent, GFP_ATOMIC); |
| BUG_ON(retval != 0); |
| i++; |
| } while_each_thread(leader, tsk); |
| rcu_read_unlock(); |
| /* remember the number of threads in the array for later. */ |
| group_size = i; |
| tset.tc_array = group; |
| tset.tc_array_len = group_size; |
| |
| /* methods shouldn't be called if no task is actually migrating */ |
| retval = 0; |
| if (!group_size) |
| goto out_free_group_list; |
| |
| /* |
| * step 1: check that we can legitimately attach to the cgroup. |
| */ |
| for_each_subsys(root, ss) { |
| if (ss->can_attach) { |
| retval = ss->can_attach(cgrp, &tset); |
| if (retval) { |
| failed_ss = ss; |
| goto out_cancel_attach; |
| } |
| } |
| } |
| |
| /* |
| * step 2: make sure css_sets exist for all threads to be migrated. |
| * we use find_css_set, which allocates a new one if necessary. |
| */ |
| for (i = 0; i < group_size; i++) { |
| tc = flex_array_get(group, i); |
| tc->cg = find_css_set(tc->task->cgroups, cgrp); |
| if (!tc->cg) { |
| retval = -ENOMEM; |
| goto out_put_css_set_refs; |
| } |
| } |
| |
| /* |
| * step 3: now that we're guaranteed success wrt the css_sets, |
| * proceed to move all tasks to the new cgroup. There are no |
| * failure cases after here, so this is the commit point. |
| */ |
| for (i = 0; i < group_size; i++) { |
| tc = flex_array_get(group, i); |
| cgroup_task_migrate(cgrp, tc->cgrp, tc->task, tc->cg); |
| } |
| /* nothing is sensitive to fork() after this point. */ |
| |
| /* |
| * step 4: do subsystem attach callbacks. |
| */ |
| for_each_subsys(root, ss) { |
| if (ss->attach) |
| ss->attach(cgrp, &tset); |
| } |
| |
| /* |
| * step 5: success! and cleanup |
| */ |
| retval = 0; |
| out_put_css_set_refs: |
| if (retval) { |
| for (i = 0; i < group_size; i++) { |
| tc = flex_array_get(group, i); |
| if (!tc->cg) |
| break; |
| put_css_set(tc->cg); |
| } |
| } |
| out_cancel_attach: |
| if (retval) { |
| for_each_subsys(root, ss) { |
| if (ss == failed_ss) |
| break; |
| if (ss->cancel_attach) |
| ss->cancel_attach(cgrp, &tset); |
| } |
| } |
| out_free_group_list: |
| flex_array_free(group); |
| return retval; |
| } |
| |
| /* |
| * 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; may take task_lock of task. |
| */ |
| static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup) |
| { |
| struct task_struct *tsk; |
| const struct cred *cred = current_cred(), *tcred; |
| int ret; |
| |
| if (!cgroup_lock_live_group(cgrp)) |
| return -ENODEV; |
| |
| retry_find_task: |
| rcu_read_lock(); |
| if (pid) { |
| tsk = find_task_by_vpid(pid); |
| if (!tsk) { |
| rcu_read_unlock(); |
| ret= -ESRCH; |
| goto out_unlock_cgroup; |
| } |
| /* |
| * even if we're attaching all tasks in the thread group, we |
| * only need to check permissions on one of them. |
| */ |
| tcred = __task_cred(tsk); |
| if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) && |
| !uid_eq(cred->euid, tcred->uid) && |
| !uid_eq(cred->euid, tcred->suid)) { |
| rcu_read_unlock(); |
| ret = -EACCES; |
| goto out_unlock_cgroup; |
| } |
| } 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; |
| rcu_read_unlock(); |
| goto out_unlock_cgroup; |
| } |
| |
| get_task_struct(tsk); |
| rcu_read_unlock(); |
| |
| threadgroup_lock(tsk); |
| if (threadgroup) { |
| if (!thread_group_leader(tsk)) { |
| /* |
| * a race with de_thread from another thread's exec() |
| * may strip us of our leadership, if this happens, |
| * there is no choice but to throw this task away and |
| * try again; this is |
| * "double-double-toil-and-trouble-check locking". |
| */ |
| threadgroup_unlock(tsk); |
| put_task_struct(tsk); |
| goto retry_find_task; |
| } |
| ret = cgroup_attach_proc(cgrp, tsk); |
| } else |
| ret = cgroup_attach_task(cgrp, tsk); |
| threadgroup_unlock(tsk); |
| |
| put_task_struct(tsk); |
| out_unlock_cgroup: |
| cgroup_unlock(); |
| return ret; |
| } |
| |
| static int cgroup_tasks_write(struct cgroup *cgrp, struct cftype *cft, u64 pid) |
| { |
| return attach_task_by_pid(cgrp, pid, false); |
| } |
| |
| static int cgroup_procs_write(struct cgroup *cgrp, struct cftype *cft, u64 tgid) |
| { |
| return attach_task_by_pid(cgrp, tgid, true); |
| } |
| |
| /** |
| * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive. |
| * @cgrp: the cgroup to be checked for liveness |
| * |
| * On success, returns true; the lock should be later released with |
| * cgroup_unlock(). On failure returns false with no lock held. |
| */ |
| bool cgroup_lock_live_group(struct cgroup *cgrp) |
| { |
| mutex_lock(&cgroup_mutex); |
| if (cgroup_is_removed(cgrp)) { |
| mutex_unlock(&cgroup_mutex); |
| return false; |
| } |
| return true; |
| } |
| EXPORT_SYMBOL_GPL(cgroup_lock_live_group); |
| |
| static int cgroup_release_agent_write(struct cgroup *cgrp, struct cftype *cft, |
| const char *buffer) |
| { |
| BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); |
| if (strlen(buffer) >= PATH_MAX) |
| return -EINVAL; |
| if (!cgroup_lock_live_group(cgrp)) |
| return -ENODEV; |
| mutex_lock(&cgroup_root_mutex); |
| strcpy(cgrp->root->release_agent_path, buffer); |
| mutex_unlock(&cgroup_root_mutex); |
| cgroup_unlock(); |
| return 0; |
| } |
| |
| static int cgroup_release_agent_show(struct cgroup *cgrp, struct cftype *cft, |
| struct seq_file *seq) |
| { |
| if (!cgroup_lock_live_group(cgrp)) |
| return -ENODEV; |
| seq_puts(seq, cgrp->root->release_agent_path); |
| seq_putc(seq, '\n'); |
| cgroup_unlock(); |
| return 0; |
| } |
| |
| /* A buffer size big enough for numbers or short strings */ |
| #define CGROUP_LOCAL_BUFFER_SIZE 64 |
| |
| static ssize_t cgroup_write_X64(struct cgroup *cgrp, struct cftype *cft, |
| struct file *file, |
| const char __user *userbuf, |
| size_t nbytes, loff_t *unused_ppos) |
| { |
| char buffer[CGROUP_LOCAL_BUFFER_SIZE]; |
| int retval = 0; |
| char *end; |
| |
| if (!nbytes) |
| return -EINVAL; |
| if (nbytes >= sizeof(buffer)) |
| return -E2BIG; |
| if (copy_from_user(buffer, userbuf, nbytes)) |
| return -EFAULT; |
| |
| buffer[nbytes] = 0; /* nul-terminate */ |
| if (cft->write_u64) { |
| u64 val = simple_strtoull(strstrip(buffer), &end, 0); |
| if (*end) |
| return -EINVAL; |
| retval = cft->write_u64(cgrp, cft, val); |
| } else { |
| s64 val = simple_strtoll(strstrip(buffer), &end, 0); |
| if (*end) |
| return -EINVAL; |
| retval = cft->write_s64(cgrp, cft, val); |
| } |
| if (!retval) |
| retval = nbytes; |
| return retval; |
| } |
| |
| static ssize_t cgroup_write_string(struct cgroup *cgrp, struct cftype *cft, |
| struct file *file, |
| const char __user *userbuf, |
| size_t nbytes, loff_t *unused_ppos) |
| { |
| char local_buffer[CGROUP_LOCAL_BUFFER_SIZE]; |
| int retval = 0; |
| size_t max_bytes = cft->max_write_len; |
| char *buffer = local_buffer; |
| |
| if (!max_bytes) |
| max_bytes = sizeof(local_buffer) - 1; |
| if (nbytes >= max_bytes) |
| return -E2BIG; |
| /* Allocate a dynamic buffer if we need one */ |
| if (nbytes >= sizeof(local_buffer)) { |
| buffer = kmalloc(nbytes + 1, GFP_KERNEL); |
| if (buffer == NULL) |
| return -ENOMEM; |
| } |
| if (nbytes && copy_from_user(buffer, userbuf, nbytes)) { |
| retval = -EFAULT; |
| goto out; |
| } |
| |
| buffer[nbytes] = 0; /* nul-terminate */ |
| retval = cft->write_string(cgrp, cft, strstrip(buffer)); |
| if (!retval) |
| retval = nbytes; |
| out: |
| if (buffer != local_buffer) |
| kfree(buffer); |
| return retval; |
| } |
| |
| static ssize_t cgroup_file_write(struct file *file, const char __user *buf, |
| size_t nbytes, loff_t *ppos) |
| { |
| struct cftype *cft = __d_cft(file->f_dentry); |
| struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
| |
| if (cgroup_is_removed(cgrp)) |
| return -ENODEV; |
| if (cft->write) |
| return cft->write(cgrp, cft, file, buf, nbytes, ppos); |
| if (cft->write_u64 || cft->write_s64) |
| return cgroup_write_X64(cgrp, cft, file, buf, nbytes, ppos); |
| if (cft->write_string) |
| return cgroup_write_string(cgrp, cft, file, buf, nbytes, ppos); |
| if (cft->trigger) { |
| int ret = cft->trigger(cgrp, (unsigned int)cft->private); |
| return ret ? ret : nbytes; |
| } |
| return -EINVAL; |
| } |
| |
| static ssize_t cgroup_read_u64(struct cgroup *cgrp, struct cftype *cft, |
| struct file *file, |
| char __user *buf, size_t nbytes, |
| loff_t *ppos) |
| { |
| char tmp[CGROUP_LOCAL_BUFFER_SIZE]; |
| u64 val = cft->read_u64(cgrp, cft); |
| int len = sprintf(tmp, "%llu\n", (unsigned long long) val); |
| |
| return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); |
| } |
| |
| static ssize_t cgroup_read_s64(struct cgroup *cgrp, struct cftype *cft, |
| struct file *file, |
| char __user *buf, size_t nbytes, |
| loff_t *ppos) |
| { |
| char tmp[CGROUP_LOCAL_BUFFER_SIZE]; |
| s64 val = cft->read_s64(cgrp, cft); |
| int len = sprintf(tmp, "%lld\n", (long long) val); |
| |
| return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); |
| } |
| |
| static ssize_t cgroup_file_read(struct file *file, char __user *buf, |
| size_t nbytes, loff_t *ppos) |
| { |
| struct cftype *cft = __d_cft(file->f_dentry); |
| struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
| |
| if (cgroup_is_removed(cgrp)) |
| return -ENODEV; |
| |
| if (cft->read) |
| return cft->read(cgrp, cft, file, buf, nbytes, ppos); |
| if (cft->read_u64) |
| return cgroup_read_u64(cgrp, cft, file, buf, nbytes, ppos); |
| if (cft->read_s64) |
| return cgroup_read_s64(cgrp, cft, file, buf, nbytes, ppos); |
| return -EINVAL; |
| } |
| |
| /* |
| * seqfile ops/methods for returning structured data. Currently just |
| * supports string->u64 maps, but can be extended in future. |
| */ |
| |
| struct cgroup_seqfile_state { |
| struct cftype *cft; |
| struct cgroup *cgroup; |
| }; |
| |
| static int cgroup_map_add(struct cgroup_map_cb *cb, const char *key, u64 value) |
| { |
| struct seq_file *sf = cb->state; |
| return seq_printf(sf, "%s %llu\n", key, (unsigned long long)value); |
| } |
| |
| static int cgroup_seqfile_show(struct seq_file *m, void *arg) |
| { |
| struct cgroup_seqfile_state *state = m->private; |
| struct cftype *cft = state->cft; |
| if (cft->read_map) { |
| struct cgroup_map_cb cb = { |
| .fill = cgroup_map_add, |
| .state = m, |
| }; |
| return cft->read_map(state->cgroup, cft, &cb); |
| } |
| return cft->read_seq_string(state->cgroup, cft, m); |
| } |
| |
| static int cgroup_seqfile_release(struct inode *inode, struct file *file) |
| { |
| struct seq_file *seq = file->private_data; |
| kfree(seq->private); |
| return single_release(inode, file); |
| } |
| |
| static const struct file_operations cgroup_seqfile_operations = { |
| .read = seq_read, |
| .write = cgroup_file_write, |
| .llseek = seq_lseek, |
| .release = cgroup_seqfile_release, |
| }; |
| |
| static int cgroup_file_open(struct inode *inode, struct file *file) |
| { |
| int err; |
| struct cftype *cft; |
| |
| err = generic_file_open(inode, file); |
| if (err) |
| return err; |
| cft = __d_cft(file->f_dentry); |
| |
| if (cft->read_map || cft->read_seq_string) { |
| struct cgroup_seqfile_state *state = |
| kzalloc(sizeof(*state), GFP_USER); |
| if (!state) |
| return -ENOMEM; |
| state->cft = cft; |
| state->cgroup = __d_cgrp(file->f_dentry->d_parent); |
| file->f_op = &cgroup_seqfile_operations; |
| err = single_open(file, cgroup_seqfile_show, state); |
| if (err < 0) |
| kfree(state); |
| } else if (cft->open) |
| err = cft->open(inode, file); |
| else |
| err = 0; |
| |
| return err; |
| } |
| |
| static int cgroup_file_release(struct inode *inode, struct file *file) |
| { |
| struct cftype *cft = __d_cft(file->f_dentry); |
| if (cft->release) |
| return cft->release(inode, file); |
| return 0; |
| } |
| |
| /* |
| * cgroup_rename - Only allow simple rename of directories in place. |
| */ |
| static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry, |
| struct inode *new_dir, struct dentry *new_dentry) |
| { |
| if (!S_ISDIR(old_dentry->d_inode->i_mode)) |
| return -ENOTDIR; |
| if (new_dentry->d_inode) |
| return -EEXIST; |
| if (old_dir != new_dir) |
| return -EIO; |
| return simple_rename(old_dir, old_dentry, new_dir, new_dentry); |
| } |
| |
| static struct simple_xattrs *__d_xattrs(struct dentry *dentry) |
| { |
| if (S_ISDIR(dentry->d_inode->i_mode)) |
| return &__d_cgrp(dentry)->xattrs; |
| else |
| return &__d_cft(dentry)->xattrs; |
| } |
| |
| static inline int xattr_enabled(struct dentry *dentry) |
| { |
| struct cgroupfs_root *root = dentry->d_sb->s_fs_info; |
| return test_bit(ROOT_XATTR, &root->flags); |
| } |
| |
| static bool is_valid_xattr(const char *name) |
| { |
| if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) || |
| !strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) |
| return true; |
| return false; |
| } |
| |
| static int cgroup_setxattr(struct dentry *dentry, const char *name, |
| const void *val, size_t size, int flags) |
| { |
| if (!xattr_enabled(dentry)) |
| return -EOPNOTSUPP; |
| if (!is_valid_xattr(name)) |
| return -EINVAL; |
| return simple_xattr_set(__d_xattrs(dentry), name, val, size, flags); |
| } |
| |
| static int cgroup_removexattr(struct dentry *dentry, const char *name) |
| { |
| if (!xattr_enabled(dentry)) |
| return -EOPNOTSUPP; |
| if (!is_valid_xattr(name)) |
| return -EINVAL; |
| return simple_xattr_remove(__d_xattrs(dentry), name); |
| } |
| |
| static ssize_t cgroup_getxattr(struct dentry *dentry, const char *name, |
| void *buf, size_t size) |
| { |
| if (!xattr_enabled(dentry)) |
| return -EOPNOTSUPP; |
| if (!is_valid_xattr(name)) |
| return -EINVAL; |
| return simple_xattr_get(__d_xattrs(dentry), name, buf, size); |
| } |
| |
| static ssize_t cgroup_listxattr(struct dentry *dentry, char *buf, size_t size) |
| { |
| if (!xattr_enabled(dentry)) |
| return -EOPNOTSUPP; |
| return simple_xattr_list(__d_xattrs(dentry), buf, size); |
| } |
| |
| static const struct file_operations cgroup_file_operations = { |
| .read = cgroup_file_read, |
| .write = cgroup_file_write, |
| .llseek = generic_file_llseek, |
| .open = cgroup_file_open, |
| .release = cgroup_file_release, |
| }; |
| |
| static const struct inode_operations cgroup_file_inode_operations = { |
| .setxattr = cgroup_setxattr, |
| .getxattr = cgroup_getxattr, |
| .listxattr = cgroup_listxattr, |
| .removexattr = cgroup_removexattr, |
| }; |
| |
| static const struct inode_operations cgroup_dir_inode_operations = { |
| .lookup = cgroup_lookup, |
| .mkdir = cgroup_mkdir, |
| .rmdir = cgroup_rmdir, |
| .rename = cgroup_rename, |
| .setxattr = cgroup_setxattr, |
| .getxattr = cgroup_getxattr, |
| .listxattr = cgroup_listxattr, |
| .removexattr = cgroup_removexattr, |
| }; |
| |
| static struct dentry *cgroup_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) |
| { |
| if (dentry->d_name.len > NAME_MAX) |
| return ERR_PTR(-ENAMETOOLONG); |
| d_add(dentry, NULL); |
| return NULL; |
| } |
| |
| /* |
| * Check if a file is a control file |
| */ |
| static inline struct cftype *__file_cft(struct file *file) |
| { |
| if (file_inode(file)->i_fop != &cgroup_file_operations) |
| return ERR_PTR(-EINVAL); |
| return __d_cft(file->f_dentry); |
| } |
| |
| static int cgroup_create_file(struct dentry *dentry, umode_t mode, |
| struct super_block *sb) |
| { |
| struct inode *inode; |
| |
| if (!dentry) |
| return -ENOENT; |
| if (dentry->d_inode) |
| return -EEXIST; |
| |
| inode = cgroup_new_inode(mode, sb); |
| if (!inode) |
| return -ENOMEM; |
| |
| if (S_ISDIR(mode)) { |
| inode->i_op = &cgroup_dir_inode_operations; |
| inode->i_fop = &simple_dir_operations; |
| |
| /* start off with i_nlink == 2 (for "." entry) */ |
| inc_nlink(inode); |
| inc_nlink(dentry->d_parent->d_inode); |
| |
| /* |
| * Control reaches here with cgroup_mutex held. |
| * @inode->i_mutex should nest outside cgroup_mutex but we |
| * want to populate it immediately without releasing |
| * cgroup_mutex. As @inode isn't visible to anyone else |
| * yet, trylock will always succeed without affecting |
| * lockdep checks. |
| */ |
| WARN_ON_ONCE(!mutex_trylock(&inode->i_mutex)); |
| } else if (S_ISREG(mode)) { |
| inode->i_size = 0; |
| inode->i_fop = &cgroup_file_operations; |
| inode->i_op = &cgroup_file_inode_operations; |
| } |
| d_instantiate(dentry, inode); |
| dget(dentry); /* Extra count - pin the dentry in core */ |
| return 0; |
| } |
| |
| /** |
| * cgroup_file_mode - deduce file mode of a control file |
| * @cft: the control file in question |
| * |
| * returns cft->mode if ->mode is not 0 |
| * returns S_IRUGO|S_IWUSR if it has both a read and a write handler |
| * returns S_IRUGO if it has only a read handler |
| * returns S_IWUSR if it has only a write hander |
| */ |
| static umode_t cgroup_file_mode(const struct cftype *cft) |
| { |
| umode_t mode = 0; |
| |
| if (cft->mode) |
| return cft->mode; |
| |
| if (cft->read || cft->read_u64 || cft->read_s64 || |
| cft->read_map || cft->read_seq_string) |
| mode |= S_IRUGO; |
| |
| if (cft->write || cft->write_u64 || cft->write_s64 || |
| cft->write_string || cft->trigger) |
| mode |= S_IWUSR; |
| |
| return mode; |
| } |
| |
| static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys, |
| struct cftype *cft) |
| { |
| struct dentry *dir = cgrp->dentry; |
| struct cgroup *parent = __d_cgrp(dir); |
| struct dentry *dentry; |
| struct cfent *cfe; |
| int error; |
| umode_t mode; |
| char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 }; |
| |
| simple_xattrs_init(&cft->xattrs); |
| |
| if (subsys && !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) { |
| strcpy(name, subsys->name); |
| strcat(name, "."); |
| } |
| strcat(name, cft->name); |
| |
| BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex)); |
| |
| cfe = kzalloc(sizeof(*cfe), GFP_KERNEL); |
| if (!cfe) |
| return -ENOMEM; |
| |
| dentry = lookup_one_len(name, dir, strlen(name)); |
| if (IS_ERR(dentry)) { |
| error = PTR_ERR(dentry); |
| goto out; |
| } |
| |
| mode = cgroup_file_mode(cft); |
| error = cgroup_create_file(dentry, mode | S_IFREG, cgrp->root->sb); |
| if (!error) { |
| cfe->type = (void *)cft; |
| cfe->dentry = dentry; |
| dentry->d_fsdata = cfe; |
| list_add_tail(&cfe->node, &parent->files); |
| cfe = NULL; |
| } |
| dput(dentry); |
| out: |
| kfree(cfe); |
| return error; |
| } |
| |
| static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys, |
| struct cftype cfts[], bool is_add) |
| { |
| struct cftype *cft; |
| int err, ret = 0; |
| |
| for (cft = cfts; cft->name[0] != '\0'; cft++) { |
| /* does cft->flags tell us to skip this file on @cgrp? */ |
| if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent) |
| continue; |
| if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent) |
| continue; |
| |
| if (is_add) { |
| err = cgroup_add_file(cgrp, subsys, cft); |
| if (err) |
| pr_warn("cgroup_addrm_files: failed to add %s, err=%d\n", |
| cft->name, err); |
| ret = err; |
| } else { |
| cgroup_rm_file(cgrp, cft); |
| } |
| } |
| return ret; |
| } |
| |
| static DEFINE_MUTEX(cgroup_cft_mutex); |
| |
| static void cgroup_cfts_prepare(void) |
| __acquires(&cgroup_cft_mutex) __acquires(&cgroup_mutex) |
| { |
| /* |
| * Thanks to the entanglement with vfs inode locking, we can't walk |
| * the existing cgroups under cgroup_mutex and create files. |
| * Instead, we increment reference on all cgroups and build list of |
| * them using @cgrp->cft_q_node. Grab cgroup_cft_mutex to ensure |
| * exclusive access to the field. |
| */ |
| mutex_lock(&cgroup_cft_mutex); |
| mutex_lock(&cgroup_mutex); |
| } |
| |
| static void cgroup_cfts_commit(struct cgroup_subsys *ss, |
| struct cftype *cfts, bool is_add) |
| __releases(&cgroup_mutex) __releases(&cgroup_cft_mutex) |
| { |
| LIST_HEAD(pending); |
| struct cgroup *cgrp, *n; |
| |
| /* %NULL @cfts indicates abort and don't bother if @ss isn't attached */ |
| if (cfts && ss->root != &rootnode) { |
| list_for_each_entry(cgrp, &ss->root->allcg_list, allcg_node) { |
| dget(cgrp->dentry); |
| list_add_tail(&cgrp->cft_q_node, &pending); |
| } |
| } |
| |
| mutex_unlock(&cgroup_mutex); |
| |
| /* |
| * All new cgroups will see @cfts update on @ss->cftsets. Add/rm |
| * files for all cgroups which were created before. |
| */ |
| list_for_each_entry_safe(cgrp, n, &pending, cft_q_node) { |
| struct inode *inode = cgrp->dentry->d_inode; |
| |
| mutex_lock(&inode->i_mutex); |
| mutex_lock(&cgroup_mutex); |
| if (!cgroup_is_removed(cgrp)) |
| cgroup_addrm_files(cgrp, ss, cfts, is_add); |
| mutex_unlock(&cgroup_mutex); |
| mutex_unlock(&inode->i_mutex); |
| |
| list_del_init(&cgrp->cft_q_node); |
| dput(cgrp->dentry); |
| } |
| |
| mutex_unlock(&cgroup_cft_mutex); |
| } |
| |
| /** |
| * 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. |
| */ |
| int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
| { |
| struct cftype_set *set; |
| |
| set = kzalloc(sizeof(*set), GFP_KERNEL); |
| if (!set) |
| return -ENOMEM; |
| |
| cgroup_cfts_prepare(); |
| set->cfts = cfts; |
| list_add_tail(&set->node, &ss->cftsets); |
| cgroup_cfts_commit(ss, cfts, true); |
| |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(cgroup_add_cftypes); |
| |
| /** |
| * cgroup_rm_cftypes - remove an array of cftypes from a subsystem |
| * @ss: target cgroup subsystem |
| * @cfts: zero-length name terminated array of cftypes |
| * |
| * Unregister @cfts from @ss. Files described by @cfts are removed from |
| * all existing cgroups to which @ss is attached and all future cgroups |
| * won't have them either. This function can be called anytime whether @ss |
| * is attached or not. |
| * |
| * Returns 0 on successful unregistration, -ENOENT if @cfts is not |
| * registered with @ss. |
| */ |
| int cgroup_rm_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
| { |
| struct cftype_set *set; |
| |
| cgroup_cfts_prepare(); |
| |
| list_for_each_entry(set, &ss->cftsets, node) { |
| if (set->cfts == cfts) { |
| list_del_init(&set->node); |
| cgroup_cfts_commit(ss, cfts, false); |
| return 0; |
| } |
| } |
| |
| cgroup_cfts_commit(ss, NULL, false); |
| return -ENOENT; |
| } |
| |
| /** |
| * cgroup_task_count - count the number of tasks in a cgroup. |
| * @cgrp: the cgroup in question |
| * |
| * Return the number of tasks in the cgroup. |
| */ |
| int cgroup_task_count(const struct cgroup *cgrp) |
| { |
| int count = 0; |
| struct cg_cgroup_link *link; |
| |
| read_lock(&css_set_lock); |
| list_for_each_entry(link, &cgrp->css_sets, cgrp_link_list) { |
| count += atomic_read(&link->cg->refcount); |
| } |
| read_unlock(&css_set_lock); |
| return count; |
| } |
| |
| /* |
| * Advance a list_head iterator. The iterator should be positioned at |
| * the start of a css_set |
| */ |
| static void cgroup_advance_iter(struct cgroup *cgrp, |
| struct cgroup_iter *it) |
| { |
| struct list_head *l = it->cg_link; |
| struct cg_cgroup_link *link; |
| struct css_set *cg; |
| |
| /* Advance to the next non-empty css_set */ |
| do { |
| l = l->next; |
| if (l == &cgrp->css_sets) { |
| it->cg_link = NULL; |
| return; |
| } |
| link = list_entry(l, struct cg_cgroup_link, cgrp_link_list); |
| cg = link->cg; |
| } while (list_empty(&cg->tasks)); |
| it->cg_link = l; |
| it->task = cg->tasks.next; |
| } |
| |
| /* |
| * 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 call to cgroup_iter_start(). |
| */ |
| static void cgroup_enable_task_cg_lists(void) |
| { |
| struct task_struct *p, *g; |
| write_lock(&css_set_lock); |
| use_task_css_set_links = 1; |
| /* |
| * 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) { |
| task_lock(p); |
| /* |
| * 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. |
| */ |
| if (!(p->flags & PF_EXITING) && list_empty(&p->cg_list)) |
| list_add(&p->cg_list, &p->cgroups->tasks); |
| task_unlock(p); |
| } while_each_thread(g, p); |
| read_unlock(&tasklist_lock); |
| write_unlock(&css_set_lock); |
| } |
| |
| /** |
| * cgroup_next_descendant_pre - find the next descendant for pre-order walk |
| * @pos: the current position (%NULL to initiate traversal) |
| * @cgroup: cgroup whose descendants to walk |
| * |
| * To be used by cgroup_for_each_descendant_pre(). Find the next |
| * descendant to visit for pre-order traversal of @cgroup's descendants. |
| */ |
| struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos, |
| struct cgroup *cgroup) |
| { |
| struct cgroup *next; |
| |
| WARN_ON_ONCE(!rcu_read_lock_held()); |
| |
| /* if first iteration, pretend we just visited @cgroup */ |
| if (!pos) { |
| if (list_empty(&cgroup->children)) |
| return NULL; |
| pos = cgroup; |
| } |
| |
| /* visit the first child if exists */ |
| next = list_first_or_null_rcu(&pos->children, struct cgroup, sibling); |
| if (next) |
| return next; |
| |
| /* no child, visit my or the closest ancestor's next sibling */ |
| do { |
| next = list_entry_rcu(pos->sibling.next, struct cgroup, |
| sibling); |
| if (&next->sibling != &pos->parent->children) |
| return next; |
| |
| pos = pos->parent; |
| } while (pos != cgroup); |
| |
| return NULL; |
| } |
| EXPORT_SYMBOL_GPL(cgroup_next_descendant_pre); |
| |
| /** |
| * cgroup_rightmost_descendant - return the rightmost descendant of a cgroup |
| * @pos: cgroup 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. |
| */ |
| struct cgroup *cgroup_rightmost_descendant(struct cgroup *pos) |
| { |
| struct cgroup *last, *tmp; |
| |
| WARN_ON_ONCE(!rcu_read_lock_held()); |
| |
| do { |
| last = pos; |
| /* ->prev isn't RCU safe, walk ->next till the end */ |
| pos = NULL; |
| list_for_each_entry_rcu(tmp, &last->children, sibling) |
| pos = tmp; |
| } while (pos); |
| |
| return last; |
| } |
| EXPORT_SYMBOL_GPL(cgroup_rightmost_descendant); |
| |
| static struct cgroup *cgroup_leftmost_descendant(struct cgroup *pos) |
| { |
| struct cgroup *last; |
| |
| do { |
| last = pos; |
| pos = list_first_or_null_rcu(&pos->children, struct cgroup, |
| sibling); |
| } while (pos); |
| |
| return last; |
| } |
| |
| /** |
| * cgroup_next_descendant_post - find the next descendant for post-order walk |
| * @pos: the current position (%NULL to initiate traversal) |
| * @cgroup: cgroup whose descendants to walk |
| * |
| * To be used by cgroup_for_each_descendant_post(). Find the next |
| * descendant to visit for post-order traversal of @cgroup's descendants. |
| */ |
| struct cgroup *cgroup_next_descendant_post(struct cgroup *pos, |
| struct cgroup *cgroup) |
| { |
| struct cgroup *next; |
| |
| WARN_ON_ONCE(!rcu_read_lock_held()); |
| |
| /* if first iteration, visit the leftmost descendant */ |
| if (!pos) { |
| next = cgroup_leftmost_descendant(cgroup); |
| return next != cgroup ? next : NULL; |
| } |
| |
| /* if there's an unvisited sibling, visit its leftmost descendant */ |
| next = list_entry_rcu(pos->sibling.next, struct cgroup, sibling); |
| if (&next->sibling != &pos->parent->children) |
| return cgroup_leftmost_descendant(next); |
| |
| /* no sibling left, visit parent */ |
| next = pos->parent; |
| return next != cgroup ? next : NULL; |
| } |
| EXPORT_SYMBOL_GPL(cgroup_next_descendant_post); |
| |
| void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it) |
| __acquires(css_set_lock) |
| { |
| /* |
| * The first time anyone tries to iterate across a cgroup, |
| * we need to 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(); |
| |
| read_lock(&css_set_lock); |
| it->cg_link = &cgrp->css_sets; |
| cgroup_advance_iter(cgrp, it); |
| } |
| |
| struct task_struct *cgroup_iter_next(struct cgroup *cgrp, |
| struct cgroup_iter *it) |
| { |
| struct task_struct *res; |
| struct list_head *l = it->task; |
| struct cg_cgroup_link *link; |
| |
| /* If the iterator cg is NULL, we have no tasks */ |
| if (!it->cg_link) |
| return NULL; |
| res = list_entry(l, struct task_struct, cg_list); |
| /* Advance iterator to find next entry */ |
| l = l->next; |
| link = list_entry(it->cg_link, struct cg_cgroup_link, cgrp_link_list); |
| if (l == &link->cg->tasks) { |
| /* We reached the end of this task list - move on to |
| * the next cg_cgroup_link */ |
| cgroup_advance_iter(cgrp, it); |
| } else { |
| it->task = l; |
| } |
| return res; |
| } |
| |
| void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it) |
| __releases(css_set_lock) |
| { |
| read_unlock(&css_set_lock); |
| } |
| |
| static inline int started_after_time(struct task_struct *t1, |
| struct timespec *time, |
| struct task_struct *t2) |
| { |
| int start_diff = timespec_compare(&t1->start_time, time); |
| if (start_diff > 0) { |
| return 1; |
| } else if (start_diff < 0) { |
| return 0; |
| } else { |
| /* |
| * Arbitrarily, if two processes started at the same |
| * time, we'll say that the lower pointer value |
| * started first. Note that t2 may have exited by now |
| * so this may not be a valid pointer any longer, but |
| * that's fine - it still serves to distinguish |
| * between two tasks started (effectively) simultaneously. |
| */ |
| return t1 > t2; |
| } |
| } |
| |
| /* |
| * This function is a callback from heap_insert() and is used to order |
| * the heap. |
| * In this case we order the heap in descending task start time. |
| */ |
| static inline int started_after(void *p1, void *p2) |
| { |
| struct task_struct *t1 = p1; |
| struct task_struct *t2 = p2; |
| return started_after_time(t1, &t2->start_time, t2); |
| } |
| |
| /** |
| * cgroup_scan_tasks - iterate though all the tasks in a cgroup |
| * @scan: struct cgroup_scanner containing arguments for the scan |
| * |
| * Arguments include pointers to callback functions test_task() and |
| * process_task(). |
| * Iterate through all the tasks in a cgroup, calling test_task() for each, |
| * and if it returns true, call process_task() for it also. |
| * The test_task pointer may be NULL, meaning always true (select all tasks). |
| * Effectively duplicates cgroup_iter_{start,next,end}() |
| * but does not lock css_set_lock for the call to process_task(). |
| * The struct cgroup_scanner may be embedded in any structure of the caller's |
| * creation. |
| * It is guaranteed that process_task() will act on every task that |
| * is a member of the cgroup for the duration of this call. This |
| * function may or may not call process_task() for tasks that exit |
| * or move to a different cgroup during the call, or are forked or |
| * move into the cgroup during the call. |
| * |
| * Note that test_task() may be called with locks held, and may in some |
| * situations be called multiple times for the same task, so it should |
| * be cheap. |
| * If the heap pointer in the struct cgroup_scanner is non-NULL, a heap has been |
| * pre-allocated and will be used for heap operations (and its "gt" member will |
| * be overwritten), else a temporary heap will be used (allocation of which |
| * may cause this function to fail). |
| */ |
| int cgroup_scan_tasks(struct cgroup_scanner *scan) |
| { |
| int retval, i; |
| struct cgroup_iter it; |
| struct task_struct *p, *dropped; |
| /* Never dereference latest_task, since it's not refcounted */ |
| struct task_struct *latest_task = NULL; |
| struct ptr_heap tmp_heap; |
| struct ptr_heap *heap; |
| struct timespec latest_time = { 0, 0 }; |
| |
| if (scan->heap) { |
| /* The caller supplied our heap and pre-allocated its memory */ |
| heap = scan->heap; |
| heap->gt = &started_after; |
| } else { |
| /* We need to allocate our own heap memory */ |
| heap = &tmp_heap; |
| retval = heap_init(heap, PAGE_SIZE, GFP_KERNEL, &started_after); |
| if (retval) |
| /* cannot allocate the heap */ |
| return retval; |
| } |
| |
| again: |
| /* |
| * Scan tasks in the cgroup, using the scanner's "test_task" callback |
| * to determine which are of interest, and using the scanner's |
| * "process_task" callback to process any of them that need an update. |
| * Since we don't want to hold any locks during the task updates, |
| * gather tasks to be processed in a heap structure. |
| * The heap is sorted by descending task start time. |
| * If the statically-sized heap fills up, we overflow tasks that |
| * started later, and in future iterations only consider tasks that |
| * started after the latest task in the previous pass. This |
| * guarantees forward progress and that we don't miss any tasks. |
| */ |
| heap->size = 0; |
| cgroup_iter_start(scan->cg, &it); |
| while ((p = cgroup_iter_next(scan->cg, &it))) { |
| /* |
| * Only affect tasks that qualify per the caller's callback, |
| * if he provided one |
| */ |
| if (scan->test_task && !scan->test_task(p, scan)) |
| continue; |
| /* |
| * Only process tasks that started after the last task |
| * we processed |
| */ |
| if (!started_after_time(p, &latest_time, latest_task)) |
| continue; |
| dropped = heap_insert(heap, p); |
| if (dropped == NULL) { |
| /* |
| * The new task was inserted; the heap wasn't |
| * previously full |
| */ |
| get_task_struct(p); |
| } else if (dropped != p) { |
| /* |
| * The new task was inserted, and pushed out a |
| * different task |
| */ |
| get_task_struct(p); |
| put_task_struct(dropped); |
| } |
| /* |
| * Else the new task was newer than anything already in |
| * the heap and wasn't inserted |
| */ |
| } |
| cgroup_iter_end(scan->cg, &it); |
| |
| if (heap->size) { |
| for (i = 0; i < heap->size; i++) { |
| struct task_struct *q = heap->ptrs[i]; |
| if (i == 0) { |
| latest_time = q->start_time; |
| latest_task = q; |
| } |
| /* Process the task per the caller's callback */ |
| scan->process_task(q, scan); |
| put_task_struct(q); |
| } |
| /* |
| * If we had to process any tasks at all, scan again |
| * in case some of them were in the middle of forking |
| * children that didn't get processed. |
| * Not the most efficient way to do it, but it avoids |
| * having to take callback_mutex in the fork path |
| */ |
| goto again; |
| } |
| if (heap == &tmp_heap) |
| heap_free(&tmp_heap); |
| return 0; |
| } |
| |
| /* |
| * 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; |
| /* how many files are using the current array */ |
| int use_count; |
| /* 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; |
| /* protects the other fields */ |
| struct rw_semaphore mutex; |
| }; |
| |
| /* |
| * 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) |
| { |
| if (is_vmalloc_addr(p)) |
| vfree(p); |
| else |
| kfree(p); |
| } |
| static void *pidlist_resize(void *p, int newcount) |
| { |
| void *newlist; |
| /* note: if new alloc fails, old p will still be valid either way */ |
| if (is_vmalloc_addr(p)) { |
| newlist = vmalloc(newcount * sizeof(pid_t)); |
| if (!newlist) |
| return NULL; |
| memcpy(newlist, p, newcount * sizeof(pid_t)); |
| vfree(p); |
| } else { |
| newlist = krealloc(p, newcount * sizeof(pid_t), GFP_KERNEL); |
| } |
| return newlist; |
| } |
| |
| /* |
| * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries |
| * If the new stripped list is sufficiently smaller and there's enough memory |
| * to allocate a new buffer, will let go of the unneeded memory. Returns the |
| * number of unique elements. |
| */ |
| /* is the size difference enough that we should re-allocate the array? */ |
| #define PIDLIST_REALLOC_DIFFERENCE(old, new) ((old) - PAGE_SIZE >= (new)) |
| static int pidlist_uniq(pid_t **p, int length) |
| { |
| int src, dest = 1; |
| pid_t *list = *p; |
| pid_t *newlist; |
| |
| /* |
| * 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: |
| /* |
| * if the length difference is large enough, we want to allocate a |
| * smaller buffer to save memory. if this fails due to out of memory, |
| * we'll just stay with what we've got. |
| */ |
| if (PIDLIST_REALLOC_DIFFERENCE(length, dest)) { |
| newlist = pidlist_resize(list, dest); |
| if (newlist) |
| *p = newlist; |
| } |
| return dest; |
| } |
| |
| static int cmppid(const void *a, const void *b) |
| { |
| return *(pid_t *)a - *(pid_t *)b; |
| } |
| |
| /* |
| * 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(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); |
| |
| /* |
| * We can't drop the pidlist_mutex before taking the l->mutex in case |
| * the last ref-holder is trying to remove l from the list at the same |
| * time. Holding the pidlist_mutex precludes somebody taking whichever |
| * list we find out from under us - compare release_pid_array(). |
| */ |
| mutex_lock(&cgrp->pidlist_mutex); |
| list_for_each_entry(l, &cgrp->pidlists, links) { |
| if (l->key.type == type && l->key.ns == ns) { |
| /* make sure l doesn't vanish out from under us */ |
| down_write(&l->mutex); |
| mutex_unlock(&cgrp->pidlist_mutex); |
| return l; |
| } |
| } |
| /* entry not found; create a new one */ |
| l = kmalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); |
| if (!l) { |
| mutex_unlock(&cgrp->pidlist_mutex); |
| return l; |
| } |
| init_rwsem(&l->mutex); |
| down_write(&l->mutex); |
| l->key.type = type; |
| l->key.ns = get_pid_ns(ns); |
| l->use_count = 0; /* don't increment here */ |
| l->list = NULL; |
| l->owner = cgrp; |
| list_add(&l->links, &cgrp->pidlists); |
| mutex_unlock(&cgrp->pidlist_mutex); |
| 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 cgroup_iter it; |
| struct task_struct *tsk; |
| struct cgroup_pidlist *l; |
| |
| /* |
| * 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 */ |
| cgroup_iter_start(cgrp, &it); |
| while ((tsk = cgroup_iter_next(cgrp, &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; |
| } |
| cgroup_iter_end(cgrp, &it); |
| length = n; |
| /* now sort & (if procs) strip out duplicates */ |
| sort(array, length, sizeof(pid_t), cmppid, NULL); |
| if (type == CGROUP_FILE_PROCS) |
| length = pidlist_uniq(&array, length); |
| l = cgroup_pidlist_find(cgrp, type); |
| if (!l) { |
| pidlist_free(array); |
| return -ENOMEM; |
| } |
| /* store array, freeing old if necessary - lock already held */ |
| pidlist_free(l->list); |
| l->list = array; |
| l->length = length; |
| l->use_count++; |
| up_write(&l->mutex); |
| *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) |
| { |
| int ret = -EINVAL; |
| struct cgroup *cgrp; |
| struct cgroup_iter it; |
| struct task_struct *tsk; |
| |
| /* |
| * Validate dentry by checking the superblock operations, |
| * and make sure it's a directory. |
| */ |
| if (dentry->d_sb->s_op != &cgroup_ops || |
| !S_ISDIR(dentry->d_inode->i_mode)) |
| goto err; |
| |
| ret = 0; |
| cgrp = dentry->d_fsdata; |
| |
| cgroup_iter_start(cgrp, &it); |
| while ((tsk = cgroup_iter_next(cgrp, &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; |
| } |
| } |
| cgroup_iter_end(cgrp, &it); |
| |
| err: |
| return ret; |
| } |
| |
| |
| /* |
| * 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 cgroup_pidlist *l = s->private; |
| int index = 0, pid = *pos; |
| int *iter; |
| |
| down_read(&l->mutex); |
| if (pid) { |
| int end = l->length; |
| |
| while (index < end) { |
| int mid = (index + end) / 2; |
| if (l->list[mid] == pid) { |
| index = mid; |
| break; |
| } else if (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 = *iter; |
| return iter; |
| } |
| |
| static void cgroup_pidlist_stop(struct seq_file *s, void *v) |
| { |
| struct cgroup_pidlist *l = s->private; |
| up_read(&l->mutex); |
| } |
| |
| static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) |
| { |
| struct cgroup_pidlist *l = s->private; |
| 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 = *p; |
| return p; |
| } |
| } |
| |
| static int cgroup_pidlist_show(struct seq_file *s, void *v) |
| { |
| return seq_printf(s, "%d\n", *(int *)v); |
| } |
| |
| /* |
| * seq_operations functions for iterating on pidlists through seq_file - |
| * independent of whether it's tasks or procs |
| */ |
| static const struct seq_operations cgroup_pidlist_seq_operations = { |
| .start = cgroup_pidlist_start, |
| .stop = cgroup_pidlist_stop, |
| .next = cgroup_pidlist_next, |
| .show = cgroup_pidlist_show, |
| }; |
| |
| static void cgroup_release_pid_array(struct cgroup_pidlist *l) |
| { |
| /* |
| * the case where we're the last user of this particular pidlist will |
| * have us remove it from the cgroup's list, which entails taking the |
| * mutex. since in pidlist_find the pidlist->lock depends on cgroup-> |
| * pidlist_mutex, we have to take pidlist_mutex first. |
| */ |
| mutex_lock(&l->owner->pidlist_mutex); |
| down_write(&l->mutex); |
| BUG_ON(!l->use_count); |
| if (!--l->use_count) { |
| /* we're the last user if refcount is 0; remove and free */ |
| list_del(&l->links); |
| mutex_unlock(&l->owner->pidlist_mutex); |
| pidlist_free(l->list); |
| put_pid_ns(l->key.ns); |
| up_write(&l->mutex); |
| kfree(l); |
| return; |
| } |
| mutex_unlock(&l->owner->pidlist_mutex); |
| up_write(&l->mutex); |
| } |
| |
| static int cgroup_pidlist_release(struct inode *inode, struct file *file) |
| { |
| struct cgroup_pidlist *l; |
| if (!(file->f_mode & FMODE_READ)) |
| return 0; |
| /* |
| * the seq_file will only be initialized if the file was opened for |
| * reading; hence we check if it's not null only in that case. |
| */ |
| l = ((struct seq_file *)file->private_data)->private; |
| cgroup_release_pid_array(l); |
| return seq_release(inode, file); |
| } |
| |
| static const struct file_operations cgroup_pidlist_operations = { |
| .read = seq_read, |
| .llseek = seq_lseek, |
| .write = cgroup_file_write, |
| .release = cgroup_pidlist_release, |
| }; |
| |
| /* |
| * The following functions handle opens on a file that displays a pidlist |
| * (tasks or procs). Prepare an array of the process/thread IDs of whoever's |
| * in the cgroup. |
| */ |
| /* helper function for the two below it */ |
| static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type) |
| { |
| struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
| struct cgroup_pidlist *l; |
| int retval; |
| |
| /* Nothing to do for write-only files */ |
| if (!(file->f_mode & FMODE_READ)) |
| return 0; |
| |
| /* have the array populated */ |
| retval = pidlist_array_load(cgrp, type, &l); |
| if (retval) |
| return retval; |
| /* configure file information */ |
| file->f_op = &cgroup_pidlist_operations; |
| |
| retval = seq_open(file, &cgroup_pidlist_seq_operations); |
| if (retval) { |
| cgroup_release_pid_array(l); |
| return retval; |
| } |
| ((struct seq_file *)file->private_data)->private = l; |
| return 0; |
| } |
| static int cgroup_tasks_open(struct inode *unused, struct file *file) |
| { |
| return cgroup_pidlist_open(file, CGROUP_FILE_TASKS); |
| } |
| static int cgroup_procs_open(struct inode *unused, struct file *file) |
| { |
| return cgroup_pidlist_open(file, CGROUP_FILE_PROCS); |
| } |
| |
| static u64 cgroup_read_notify_on_release(struct cgroup *cgrp, |
| struct cftype *cft) |
| { |
| return notify_on_release(cgrp); |
| } |
| |
| static int cgroup_write_notify_on_release(struct cgroup *cgrp, |
| struct cftype *cft, |
| u64 val) |
| { |
| clear_bit(CGRP_RELEASABLE, &cgrp->flags); |
| if (val) |
| set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
| else |
| clear_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
| return 0; |
| } |
| |
| /* |
| * Unregister event and free resources. |
| * |
| * Gets called from workqueue. |
| */ |
| static void cgroup_event_remove(struct work_struct *work) |
| { |
| struct cgroup_event *event = container_of(work, struct cgroup_event, |
| remove); |
| struct cgroup *cgrp = event->cgrp; |
| |
| remove_wait_queue(event->wqh, &event->wait); |
| |
| event->cft->unregister_event(cgrp, event->cft, event->eventfd); |
| |
| /* Notify userspace the event is going away. */ |
| eventfd_signal(event->eventfd, 1); |
| |
| eventfd_ctx_put(event->eventfd); |
| kfree(event); |
| dput(cgrp->dentry); |
| } |
| |
| /* |
| * Gets called on POLLHUP on eventfd when user closes it. |
| * |
| * Called with wqh->lock held and interrupts disabled. |
| */ |
| static int cgroup_event_wake(wait_queue_t *wait, unsigned mode, |
| int sync, void *key) |
| { |
| struct cgroup_event *event = container_of(wait, |
| struct cgroup_event, wait); |
| struct cgroup *cgrp = event->cgrp; |
| unsigned long flags = (unsigned long)key; |
| |
| if (flags & POLLHUP) { |
| /* |
| * If the event has been detached at cgroup removal, we |
| * can simply return knowing the other side will cleanup |
| * for us. |
| * |
| * We can't race against event freeing since the other |
| * side will require wqh->lock via remove_wait_queue(), |
| * which we hold. |
| */ |
| spin_lock(&cgrp->event_list_lock); |
| if (!list_empty(&event->list)) { |
| list_del_init(&event->list); |
| /* |
| * We are in atomic context, but cgroup_event_remove() |
| * may sleep, so we have to call it in workqueue. |
| */ |
| schedule_work(&event->remove); |
| } |
| spin_unlock(&cgrp->event_list_lock); |
| } |
| |
| return 0; |
| } |
| |
| static void cgroup_event_ptable_queue_proc(struct file *file, |
| wait_queue_head_t *wqh, poll_table *pt) |
| { |
| struct cgroup_event *event = container_of(pt, |
| struct cgroup_event, pt); |
| |
| event->wqh = wqh; |
| add_wait_queue(wqh, &event->wait); |
| } |
| |
| /* |
| * Parse input and register new cgroup event handler. |
| * |
| * Input must be in format '<event_fd> <control_fd> <args>'. |
| * Interpretation of args is defined by control file implementation. |
| */ |
| static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft, |
| const char *buffer) |
| { |
| struct cgroup_event *event = NULL; |
| struct cgroup *cgrp_cfile; |
| unsigned int efd, cfd; |
| struct file *efile = NULL; |
| struct file *cfile = NULL; |
| char *endp; |
| int ret; |
| |
| efd = simple_strtoul(buffer, &endp, 10); |
| if (*endp != ' ') |
| return -EINVAL; |
| buffer = endp + 1; |
| |
| cfd = simple_strtoul(buffer, &endp, 10); |
| if ((*endp != ' ') && (*endp != '\0')) |
| return -EINVAL; |
| buffer = endp + 1; |
| |
| event = kzalloc(sizeof(*event), GFP_KERNEL); |
| if (!event) |
| return -ENOMEM; |
| event->cgrp = cgrp; |
| INIT_LIST_HEAD(&event->list); |
| init_poll_funcptr(&event->pt, cgroup_event_ptable_queue_proc); |
| init_waitqueue_func_entry(&event->wait, cgroup_event_wake); |
| INIT_WORK(&event->remove, cgroup_event_remove); |
| |
| efile = eventfd_fget(efd); |
| if (IS_ERR(efile)) { |
| ret = PTR_ERR(efile); |
| goto fail; |
| } |
| |
| event->eventfd = eventfd_ctx_fileget(efile); |
| if (IS_ERR(event->eventfd)) { |
| ret = PTR_ERR(event->eventfd); |
| goto fail; |
| } |
| |
| cfile = fget(cfd); |
| if (!cfile) { |
| ret = -EBADF; |
| goto fail; |
| } |
| |
| /* the process need read permission on control file */ |
| /* AV: shouldn't we check that it's been opened for read instead? */ |
| ret = inode_permission(file_inode(cfile), MAY_READ); |
| if (ret < 0) |
| goto fail; |
| |
| event->cft = __file_cft(cfile); |
| if (IS_ERR(event->cft)) { |
| ret = PTR_ERR(event->cft); |
| goto fail; |
| } |
| |
| /* |
| * The file to be monitored must be in the same cgroup as |
| * cgroup.event_control is. |
| */ |
| cgrp_cfile = __d_cgrp(cfile->f_dentry->d_parent); |
| if (cgrp_cfile != cgrp) { |
| ret = -EINVAL; |
| goto fail; |
| } |
| |
| if (!event->cft->register_event || !event->cft->unregister_event) { |
| ret = -EINVAL; |
| goto fail; |
| } |
| |
| ret = event->cft->register_event(cgrp, event->cft, |
| event->eventfd, buffer); |
| if (ret) |
| goto fail; |
| |
| if (efile->f_op->poll(efile, &event->pt) & POLLHUP) { |
| event->cft->unregister_event(cgrp, event->cft, event->eventfd); |
| ret = 0; |
| goto fail; |
| } |
| |
| /* |
| * Events should be removed after rmdir of cgroup directory, but before |
| * destroying subsystem state objects. Let's take reference to cgroup |
| * directory dentry to do that. |
| */ |
| dget(cgrp->dentry); |
| |
| spin_lock(&cgrp->event_list_lock); |
| list_add(&event->list, &cgrp->event_list); |
| spin_unlock(&cgrp->event_list_lock); |
| |
| fput(cfile); |
| fput(efile); |
| |
| return 0; |
| |
| fail: |
| if (cfile) |
| fput(cfile); |
| |
| if (event && event->eventfd && !IS_ERR(event->eventfd)) |
| eventfd_ctx_put(event->eventfd); |
| |
| if (!IS_ERR_OR_NULL(efile)) |
| fput(efile); |
| |
| kfree(event); |
| |
| return ret; |
| } |
| |
| static u64 cgroup_clone_children_read(struct cgroup *cgrp, |
| struct cftype *cft) |
| { |
| return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); |
| } |
| |
| static int cgroup_clone_children_write(struct cgroup *cgrp, |
| struct cftype *cft, |
| u64 val) |
| { |
| if (val) |
| set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); |
| else |
| clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); |
| return 0; |
| } |
| |
| /* |
| * for the common functions, 'private' gives the type of file |
| */ |
| /* for hysterical raisins, we can't put this on the older files */ |
| #define CGROUP_FILE_GENERIC_PREFIX "cgroup." |
| static struct cftype files[] = { |
| { |
| .name = "tasks", |
| .open = cgroup_tasks_open, |
| .write_u64 = cgroup_tasks_write, |
| .release = cgroup_pidlist_release, |
| .mode = S_IRUGO | S_IWUSR, |
| }, |
| { |
| .name = CGROUP_FILE_GENERIC_PREFIX "procs", |
| .open = cgroup_procs_open, |
| .write_u64 = cgroup_procs_write, |
| .release = cgroup_pidlist_release, |
| .mode = S_IRUGO | S_IWUSR, |
| }, |
| { |
| .name = "notify_on_release", |
| .read_u64 = cgroup_read_notify_on_release, |
| .write_u64 = cgroup_write_notify_on_release, |
| }, |
| { |
| .name = CGROUP_FILE_GENERIC_PREFIX "event_control", |
| .write_string = cgroup_write_event_control, |
| .mode = S_IWUGO, |
| }, |
| { |
| .name = "cgroup.clone_children", |
| .read_u64 = cgroup_clone_children_read, |
| .write_u64 = cgroup_clone_children_write, |
| }, |
| { |
| .name = "release_agent", |
| .flags = CFTYPE_ONLY_ON_ROOT, |
| .read_seq_string = cgroup_release_agent_show, |
| .write_string = cgroup_release_agent_write, |
| .max_write_len = PATH_MAX, |
| }, |
| { } /* terminate */ |
| }; |
| |
| /** |
| * cgroup_populate_dir - selectively creation of files in a directory |
| * @cgrp: target cgroup |
| * @base_files: true if the base files should be added |
| * @subsys_mask: mask of the subsystem ids whose files should be added |
| */ |
| static int cgroup_populate_dir(struct cgroup *cgrp, bool base_files, |
| unsigned long subsys_mask) |
| { |
| int err; |
| struct cgroup_subsys *ss; |
| |
| if (base_files) { |
| err = cgroup_addrm_files(cgrp, NULL, files, true); |
| if (err < 0) |
| return err; |
| } |
| |
| /* process cftsets of each subsystem */ |
| for_each_subsys(cgrp->root, ss) { |
| struct cftype_set *set; |
| if (!test_bit(ss->subsys_id, &subsys_mask)) |
| continue; |
| |
| list_for_each_entry(set, &ss->cftsets, node) |
| cgroup_addrm_files(cgrp, ss, set->cfts, true); |
| } |
| |
| /* This cgroup is ready now */ |
| for_each_subsys(cgrp->root, ss) { |
| struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; |
| /* |
| * Update id->css pointer and make this css visible from |
| * CSS ID functions. This pointer will be dereferened |
| * from RCU-read-side without locks. |
| */ |
| if (css->id) |
| rcu_assign_pointer(css->id->css, css); |
| } |
| |
| return 0; |
| } |
| |
| static void css_dput_fn(struct work_struct *work) |
| { |
| struct cgroup_subsys_state *css = |
| container_of(work, struct cgroup_subsys_state, dput_work); |
| struct dentry *dentry = css->cgroup->dentry; |
| struct super_block *sb = dentry->d_sb; |
| |
| atomic_inc(&sb->s_active); |
| dput(dentry); |
| deactivate_super(sb); |
| } |
| |
| static void init_cgroup_css(struct cgroup_subsys_state *css, |
| struct cgroup_subsys *ss, |
| struct cgroup *cgrp) |
| { |
| css->cgroup = cgrp; |
| atomic_set(&css->refcnt, 1); |
| css->flags = 0; |
| css->id = NULL; |
| if (cgrp == dummytop) |
| css->flags |= CSS_ROOT; |
| BUG_ON(cgrp->subsys[ss->subsys_id]); |
| cgrp->subsys[ss->subsys_id] = css; |
| |
| /* |
| * css holds an extra ref to @cgrp->dentry which is put on the last |
| * css_put(). dput() requires process context, which css_put() may |
| * be called without. @css->dput_work will be used to invoke |
| * dput() asynchronously from css_put(). |
| */ |
| INIT_WORK(&css->dput_work, css_dput_fn); |
| } |
| |
| /* invoke ->post_create() on a new CSS and mark it online if successful */ |
| static int online_css(struct cgroup_subsys *ss, struct cgroup *cgrp) |
| { |
| int ret = 0; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| if (ss->css_online) |
| ret = ss->css_online(cgrp); |
| if (!ret) |
| cgrp->subsys[ss->subsys_id]->flags |= CSS_ONLINE; |
| return ret; |
| } |
| |
| /* if the CSS is online, invoke ->pre_destory() on it and mark it offline */ |
| static void offline_css(struct cgroup_subsys *ss, struct cgroup *cgrp) |
| __releases(&cgroup_mutex) __acquires(&cgroup_mutex) |
| { |
| struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| if (!(css->flags & CSS_ONLINE)) |
| return; |
| |
| /* |
| * css_offline() should be called with cgroup_mutex unlocked. See |
| * 3fa59dfbc3 ("cgroup: fix potential deadlock in pre_destroy") for |
| * details. This temporary unlocking should go away once |
| * cgroup_mutex is unexported from controllers. |
| */ |
| if (ss->css_offline) { |
| mutex_unlock(&cgroup_mutex); |
| ss->css_offline(cgrp); |
| mutex_lock(&cgroup_mutex); |
| } |
| |
| cgrp->subsys[ss->subsys_id]->flags &= ~CSS_ONLINE; |
| } |
| |
| /* |
| * cgroup_create - create a cgroup |
| * @parent: cgroup that will be parent of the new cgroup |
| * @dentry: dentry of the new cgroup |
| * @mode: mode to set on new inode |
| * |
| * Must be called with the mutex on the parent inode held |
| */ |
| static long cgroup_create(struct cgroup *parent, struct dentry *dentry, |
| umode_t mode) |
| { |
| struct cgroup *cgrp; |
| struct cgroupfs_root *root = parent->root; |
| int err = 0; |
| struct cgroup_subsys *ss; |
| struct super_block *sb = root->sb; |
| |
| /* allocate the cgroup and its ID, 0 is reserved for the root */ |
| cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); |
| if (!cgrp) |
| return -ENOMEM; |
| |
| cgrp->id = ida_simple_get(&root->cgroup_ida, 1, 0, GFP_KERNEL); |
| if (cgrp->id < 0) |
| goto err_free_cgrp; |
| |
| /* |
| * Only live parents can have children. Note that the liveliness |
| * check isn't strictly necessary because cgroup_mkdir() and |
| * cgroup_rmdir() are fully synchronized by i_mutex; however, do it |
| * anyway so that locking is contained inside cgroup proper and we |
| * don't get nasty surprises if we ever grow another caller. |
| */ |
| if (!cgroup_lock_live_group(parent)) { |
| err = -ENODEV; |
| goto err_free_id; |
| } |
| |
| /* Grab a reference on the superblock so the hierarchy doesn't |
| * get deleted on unmount if there are child cgroups. This |
| * can be done outside cgroup_mutex, since the sb can't |
| * disappear while someone has an open control file on the |
| * fs */ |
| atomic_inc(&sb->s_active); |
| |
| init_cgroup_housekeeping(cgrp); |
| |
| dentry->d_fsdata = cgrp; |
| cgrp->dentry = dentry; |
| |
| cgrp->parent = parent; |
| cgrp->root = parent->root; |
| cgrp->top_cgroup = parent->top_cgroup; |
| |
| 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); |
| |
| for_each_subsys(root, ss) { |
| struct cgroup_subsys_state *css; |
| |
| css = ss->css_alloc(cgrp); |
| if (IS_ERR(css)) { |
| err = PTR_ERR(css); |
| goto err_free_all; |
| } |
| init_cgroup_css(css, ss, cgrp); |
| if (ss->use_id) { |
| err = alloc_css_id(ss, parent, cgrp); |
| if (err) |
| goto err_free_all; |
| } |
| } |
| |
| /* |
| * Create directory. cgroup_create_file() returns with the new |
| * directory locked on success so that it can be populated without |
| * dropping cgroup_mutex. |
| */ |
| err = cgroup_create_file(dentry, S_IFDIR | mode, sb); |
| if (err < 0) |
| goto err_free_all; |
| lockdep_assert_held(&dentry->d_inode->i_mutex); |
| |
| /* allocation complete, commit to creation */ |
| list_add_tail(&cgrp->allcg_node, &root->allcg_list); |
| list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children); |
| root->number_of_cgroups++; |
| |
| /* each css holds a ref to the cgroup's dentry */ |
| for_each_subsys(root, ss) |
| dget(dentry); |
| |
| /* creation succeeded, notify subsystems */ |
| for_each_subsys(root, ss) { |
| err = online_css(ss, cgrp); |
| if (err) |
| goto err_destroy; |
| |
| if (ss->broken_hierarchy && !ss->warned_broken_hierarchy && |
| parent->parent) { |
| pr_warning("cgroup: %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_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n"); |
| ss->warned_broken_hierarchy = true; |
| } |
| } |
| |
| err = cgroup_populate_dir(cgrp, true, root->subsys_mask); |
| if (err) |
| goto err_destroy; |
| |
| mutex_unlock(&cgroup_mutex); |
| mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
| |
| return 0; |
| |
| err_free_all: |
| for_each_subsys(root, ss) { |
| if (cgrp->subsys[ss->subsys_id]) |
| ss->css_free(cgrp); |
| } |
| mutex_unlock(&cgroup_mutex); |
| /* Release the reference count that we took on the superblock */ |
| deactivate_super(sb); |
| err_free_id: |
| ida_simple_remove(&root->cgroup_ida, cgrp->id); |
| err_free_cgrp: |
| kfree(cgrp); |
| return err; |
| |
| err_destroy: |
| cgroup_destroy_locked(cgrp); |
| mutex_unlock(&cgroup_mutex); |
| mutex_unlock(&dentry->d_inode->i_mutex); |
| return err; |
| } |
| |
| static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
| { |
| struct cgroup *c_parent = dentry->d_parent->d_fsdata; |
| |
| /* the vfs holds inode->i_mutex already */ |
| return cgroup_create(c_parent, dentry, mode | S_IFDIR); |
| } |
| |
| /* |
| * Check the reference count on each subsystem. Since we already |
| * established that there are no tasks in the cgroup, if the css refcount |
| * is also 1, then there should be no outstanding references, so the |
| * subsystem is safe to destroy. We scan across all subsystems rather than |
| * using the per-hierarchy linked list of mounted subsystems since we can |
| * be called via check_for_release() with no synchronization other than |
| * RCU, and the subsystem linked list isn't RCU-safe. |
| */ |
| static int cgroup_has_css_refs(struct cgroup *cgrp) |
| { |
| int i; |
| |
| /* |
| * We won't need to lock the subsys array, because the subsystems |
| * we're concerned about aren't going anywhere since our cgroup root |
| * has a reference on them. |
| */ |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| struct cgroup_subsys *ss = subsys[i]; |
| struct cgroup_subsys_state *css; |
| |
| /* Skip subsystems not present or not in this hierarchy */ |
| if (ss == NULL || ss->root != cgrp->root) |
| continue; |
| |
| css = cgrp->subsys[ss->subsys_id]; |
| /* |
| * When called from check_for_release() it's possible |
| * that by this point the cgroup has been removed |
| * and the css deleted. But a false-positive doesn't |
| * matter, since it can only happen if the cgroup |
| * has been deleted and hence no longer needs the |
| * release agent to be called anyway. |
| */ |
| if (css && css_refcnt(css) > 1) |
| return 1; |
| } |
| return 0; |
| } |
| |
| static int cgroup_destroy_locked(struct cgroup *cgrp) |
| __releases(&cgroup_mutex) __acquires(&cgroup_mutex) |
| { |
| struct dentry *d = cgrp->dentry; |
| struct cgroup *parent = cgrp->parent; |
| DEFINE_WAIT(wait); |
| struct cgroup_event *event, *tmp; |
| struct cgroup_subsys *ss; |
| LIST_HEAD(tmp_list); |
| |
| lockdep_assert_held(&d->d_inode->i_mutex); |
| lockdep_assert_held(&cgroup_mutex); |
| |
| if (atomic_read(&cgrp->count) || !list_empty(&cgrp->children)) |
| return -EBUSY; |
| |
| /* |
| * Block new css_tryget() by deactivating refcnt and mark @cgrp |
| * removed. This makes future css_tryget() and child creation |
| * attempts fail thus maintaining the removal conditions verified |
| * above. |
| */ |
| for_each_subsys(cgrp->root, ss) { |
| struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; |
| |
| WARN_ON(atomic_read(&css->refcnt) < 0); |
| atomic_add(CSS_DEACT_BIAS, &css->refcnt); |
| } |
| set_bit(CGRP_REMOVED, &cgrp->flags); |
| |
| /* tell subsystems to initate destruction */ |
| for_each_subsys(cgrp->root, ss) |
| offline_css(ss, cgrp); |
| |
| /* |
| * Put all the base refs. Each css holds an extra reference to the |
| * cgroup's dentry and cgroup removal proceeds regardless of css |
| * refs. On the last put of each css, whenever that may be, the |
| * extra dentry ref is put so that dentry destruction happens only |
| * after all css's are released. |
| */ |
| for_each_subsys(cgrp->root, ss) |
| css_put(cgrp->subsys[ss->subsys_id]); |
| |
| raw_spin_lock(&release_list_lock); |
| if (!list_empty(&cgrp->release_list)) |
| list_del_init(&cgrp->release_list); |
| raw_spin_unlock(&release_list_lock); |
| |
| /* delete this cgroup from parent->children */ |
| list_del_rcu(&cgrp->sibling); |
| list_del_init(&cgrp->allcg_node); |
| |
| dget(d); |
| cgroup_d_remove_dir(d); |
| dput(d); |
| |
| set_bit(CGRP_RELEASABLE, &parent->flags); |
| check_for_release(parent); |
| |
| /* |
| * Unregister events and notify userspace. |
| * Notify userspace about cgroup removing only after rmdir of cgroup |
| * directory to avoid race between userspace and kernelspace. |
| */ |
| spin_lock(&cgrp->event_list_lock); |
| list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) { |
| list_del_init(&event->list); |
| schedule_work(&event->remove); |
| } |
| spin_unlock(&cgrp->event_list_lock); |
| |
| return 0; |
| } |
| |
| static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) |
| { |
| int ret; |
| |
| mutex_lock(&cgroup_mutex); |
| ret = cgroup_destroy_locked(dentry->d_fsdata); |
| mutex_unlock(&cgroup_mutex); |
| |
| return ret; |
| } |
| |
| static void __init_or_module cgroup_init_cftsets(struct cgroup_subsys *ss) |
| { |
| INIT_LIST_HEAD(&ss->cftsets); |
| |
| /* |
| * base_cftset is embedded in subsys itself, no need to worry about |
| * deregistration. |
| */ |
| if (ss->base_cftypes) { |
| ss->base_cftset.cfts = ss->base_cftypes; |
| list_add_tail(&ss->base_cftset.node, &ss->cftsets); |
| } |
| } |
| |
| static void __init cgroup_init_subsys(struct cgroup_subsys *ss) |
| { |
| struct cgroup_subsys_state *css; |
| |
| printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); |
| |
| mutex_lock(&cgroup_mutex); |
| |
| /* init base cftset */ |
| cgroup_init_cftsets(ss); |
| |
| /* Create the top cgroup state for this subsystem */ |
| list_add(&ss->sibling, &rootnode.subsys_list); |
| ss->root = &rootnode; |
| css = ss->css_alloc(dummytop); |
| /* We don't handle early failures gracefully */ |
| BUG_ON(IS_ERR(css)); |
| init_cgroup_css(css, ss, dummytop); |
| |
| /* 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 top cgroup. */ |
| init_css_set.subsys[ss->subsys_id] = css; |
| |
| need_forkexit_callback |= ss->fork || ss->exit; |
| |
| /* 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)); |
| |
| ss->active = 1; |
| BUG_ON(online_css(ss, dummytop)); |
| |
| mutex_unlock(&cgroup_mutex); |
| |
| /* this function shouldn't be used with modular subsystems, since they |
| * need to register a subsys_id, among other things */ |
| BUG_ON(ss->module); |
| } |
| |
| /** |
| * cgroup_load_subsys: load and register a modular subsystem at runtime |
| * @ss: the subsystem to load |
| * |
| * This function should be called in a modular subsystem's initcall. If the |
| * subsystem is built as a module, it will be assigned a new subsys_id and set |
| * up for use. If the subsystem is built-in anyway, work is delegated to the |
| * simpler cgroup_init_subsys. |
| */ |
| int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) |
| { |
| struct cgroup_subsys_state *css; |
| int i, ret; |
| struct hlist_node *tmp; |
| struct css_set *cg; |
| unsigned long key; |
| |
| /* check name and function validity */ |
| if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN || |
| ss->css_alloc == NULL || ss->css_free == NULL) |
| return -EINVAL; |
| |
| /* |
| * we don't support callbacks in modular subsystems. this check is |
| * before the ss->module check for consistency; a subsystem that could |
| * be a module should still have no callbacks even if the user isn't |
| * compiling it as one. |
| */ |
| if (ss->fork || ss->exit) |
| return -EINVAL; |
| |
| /* |
| * an optionally modular subsystem is built-in: we want to do nothing, |
| * since cgroup_init_subsys will have already taken care of it. |
| */ |
| if (ss->module == NULL) { |
| /* a sanity check */ |
| BUG_ON(subsys[ss->subsys_id] != ss); |
| return 0; |
| } |
| |
| /* init base cftset */ |
| cgroup_init_cftsets(ss); |
| |
| mutex_lock(&cgroup_mutex); |
| subsys[ss->subsys_id] = ss; |
| |
| /* |
| * no ss->css_alloc seems to need anything important in the ss |
| * struct, so this can happen first (i.e. before the rootnode |
| * attachment). |
| */ |
| css = ss->css_alloc(dummytop); |
| if (IS_ERR(css)) { |
| /* failure case - need to deassign the subsys[] slot. */ |
| subsys[ss->subsys_id] = NULL; |
| mutex_unlock(&cgroup_mutex); |
| return PTR_ERR(css); |
| } |
| |
| list_add(&ss->sibling, &rootnode.subsys_list); |
| ss->root = &rootnode; |
| |
| /* our new subsystem will be attached to the dummy hierarchy. */ |
| init_cgroup_css(css, ss, dummytop); |
| /* init_idr must be after init_cgroup_css because it sets css->id. */ |
| if (ss->use_id) { |
| ret = cgroup_init_idr(ss, css); |
| if (ret) |
| goto err_unload; |
| } |
| |
| /* |
| * Now we need to entangle the css into the existing css_sets. unlike |
| * in cgroup_init_subsys, there are now multiple css_sets, so each one |
| * will need a new pointer to it; done by iterating the css_set_table. |
| * furthermore, modifying the existing css_sets will corrupt the hash |
| * table state, so each changed css_set will need its hash recomputed. |
| * this is all done under the css_set_lock. |
| */ |
| write_lock(&css_set_lock); |
| hash_for_each_safe(css_set_table, i, tmp, cg, hlist) { |
| /* skip entries that we already rehashed */ |
| if (cg->subsys[ss->subsys_id]) |
| continue; |
| /* remove existing entry */ |
| hash_del(&cg->hlist); |
| /* set new value */ |
| cg->subsys[ss->subsys_id] = css; |
| /* recompute hash and restore entry */ |
| key = css_set_hash(cg->subsys); |
| hash_add(css_set_table, &cg->hlist, key); |
| } |
| write_unlock(&css_set_lock); |
| |
| ss->active = 1; |
| ret = online_css(ss, dummytop); |
| if (ret) |
| goto err_unload; |
| |
| /* success! */ |
| mutex_unlock(&cgroup_mutex); |
| return 0; |
| |
| err_unload: |
| mutex_unlock(&cgroup_mutex); |
| /* @ss can't be mounted here as try_module_get() would fail */ |
| cgroup_unload_subsys(ss); |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(cgroup_load_subsys); |
| |
| /** |
| * cgroup_unload_subsys: unload a modular subsystem |
| * @ss: the subsystem to unload |
| * |
| * This function should be called in a modular subsystem's exitcall. When this |
| * function is invoked, the refcount on the subsystem's module will be 0, so |
| * the subsystem will not be attached to any hierarchy. |
| */ |
| void cgroup_unload_subsys(struct cgroup_subsys *ss) |
| { |
| struct cg_cgroup_link *link; |
| |
| BUG_ON(ss->module == NULL); |
| |
| /* |
| * we shouldn't be called if the subsystem is in use, and the use of |
| * try_module_get in parse_cgroupfs_options should ensure that it |
| * doesn't start being used while we're killing it off. |
| */ |
| BUG_ON(ss->root != &rootnode); |
| |
| mutex_lock(&cgroup_mutex); |
| |
| offline_css(ss, dummytop); |
| ss->active = 0; |
| |
| if (ss->use_id) |
| idr_destroy(&ss->idr); |
| |
| /* deassign the subsys_id */ |
| subsys[ss->subsys_id] = NULL; |
| |
| /* remove subsystem from rootnode's list of subsystems */ |
| list_del_init(&ss->sibling); |
| |
| /* |
| * disentangle the css from all css_sets attached to the dummytop. as |
| * in loading, we need to pay our respects to the hashtable gods. |
| */ |
| write_lock(&css_set_lock); |
| list_for_each_entry(link, &dummytop->css_sets, cgrp_link_list) { |
| struct css_set *cg = link->cg; |
| unsigned long key; |
| |
| hash_del(&cg->hlist); |
| cg->subsys[ss->subsys_id] = NULL; |
| key = css_set_hash(cg->subsys); |
| hash_add(css_set_table, &cg->hlist, key); |
| } |
| write_unlock(&css_set_lock); |
| |
| /* |
| * remove subsystem's css from the dummytop and free it - need to |
| * free before marking as null because ss->css_free needs the |
| * cgrp->subsys pointer to find their state. note that this also |
| * takes care of freeing the css_id. |
| */ |
| ss->css_free(dummytop); |
| dummytop->subsys[ss->subsys_id] = NULL; |
| |
| mutex_unlock(&cgroup_mutex); |
| } |
| EXPORT_SYMBOL_GPL(cgroup_unload_subsys); |
| |
| /** |
| * 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) |
| { |
| int i; |
| atomic_set(&init_css_set.refcount, 1); |
| INIT_LIST_HEAD(&init_css_set.cg_links); |
| INIT_LIST_HEAD(&init_css_set.tasks); |
| INIT_HLIST_NODE(&init_css_set.hlist); |
| css_set_count = 1; |
| init_cgroup_root(&rootnode); |
| root_count = 1; |
| init_task.cgroups = &init_css_set; |
| |
| init_css_set_link.cg = &init_css_set; |
| init_css_set_link.cgrp = dummytop; |
| list_add(&init_css_set_link.cgrp_link_list, |
| &rootnode.top_cgroup.css_sets); |
| list_add(&init_css_set_link.cg_link_list, |
| &init_css_set.cg_links); |
| |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| struct cgroup_subsys *ss = subsys[i]; |
| |
| /* at bootup time, we don't worry about modular subsystems */ |
| if (!ss || ss->module) |
| continue; |
| |
| BUG_ON(!ss->name); |
| BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN); |
| BUG_ON(!ss->css_alloc); |
| BUG_ON(!ss->css_free); |
| if (ss->subsys_id != i) { |
| printk(KERN_ERR "cgroup: Subsys %s id == %d\n", |
| ss->name, ss->subsys_id); |
| BUG(); |
| } |
| |
| if (ss->early_init) |
| cgroup_init_subsys(ss); |
| } |
| return 0; |
| } |
| |
| /** |
| * 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) |
| { |
| int err; |
| int i; |
| unsigned long key; |
| |
| err = bdi_init(&cgroup_backing_dev_info); |
| if (err) |
| return err; |
| |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| struct cgroup_subsys *ss = subsys[i]; |
| |
| /* at bootup time, we don't worry about modular subsystems */ |
| if (!ss || ss->module) |
| continue; |
| if (!ss->early_init) |
| cgroup_init_subsys(ss); |
| if (ss->use_id) |
| cgroup_init_idr(ss, init_css_set.subsys[ss->subsys_id]); |
| } |
| |
| /* Add init_css_set to the hash table */ |
| key = css_set_hash(init_css_set.subsys); |
| hash_add(css_set_table, &init_css_set.hlist, key); |
| BUG_ON(!init_root_id(&rootnode)); |
| |
| cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj); |
| if (!cgroup_kobj) { |
| err = -ENOMEM; |
| goto out; |
| } |
| |
| err = register_filesystem(&cgroup_fs_type); |
| if (err < 0) { |
| kobject_put(cgroup_kobj); |
| goto out; |
| } |
| |
| proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations); |
| |
| out: |
| if (err) |
| bdi_destroy(&cgroup_backing_dev_info); |
| |
| return err; |
| } |
| |
| /* |
| * proc_cgroup_show() |
| * - Print task's cgroup paths into seq_file, one line for each hierarchy |
| * - Used for /proc/<pid>/cgroup. |
| * - No need to task_lock(tsk) on this tsk->cgroup reference, as it |
| * doesn't really matter if tsk->cgroup changes after we read it, |
| * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it |
| * anyway. No need to check that tsk->cgroup != NULL, thanks to |
| * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks |
| * cgroup to top_cgroup. |
| */ |
| |
| /* TODO: Use a proper seq_file iterator */ |
| static int proc_cgroup_show(struct seq_file *m, void *v) |
| { |
| struct pid *pid; |
| struct task_struct *tsk; |
| char *buf; |
| int retval; |
| struct cgroupfs_root *root; |
| |
| retval = -ENOMEM; |
| buf = kmalloc(PAGE_SIZE, GFP_KERNEL); |
| if (!buf) |
| goto out; |
| |
| retval = -ESRCH; |
| pid = m->private; |
| tsk = get_pid_task(pid, PIDTYPE_PID); |
| if (!tsk) |
| goto out_free; |
| |
| retval = 0; |
| |
| mutex_lock(&cgroup_mutex); |
| |
| for_each_active_root(root) { |
| struct cgroup_subsys *ss; |
| struct cgroup *cgrp; |
| int count = 0; |
| |
| seq_printf(m, "%d:", root->hierarchy_id); |
| for_each_subsys(root, ss) |
| seq_printf(m, "%s%s", count++ ? "," : "", ss->name); |
| if (strlen(root->name)) |
| seq_printf(m, "%sname=%s", count ? "," : "", |
| root->name); |
| seq_putc(m, ':'); |
| cgrp = task_cgroup_from_root(tsk, root); |
| retval = cgroup_path(cgrp, buf, PAGE_SIZE); |
| if (retval < 0) |
| goto out_unlock; |
| seq_puts(m, buf); |
| seq_putc(m, '\n'); |
| } |
| |
| out_unlock: |
| mutex_unlock(&cgroup_mutex); |
| put_task_struct(tsk); |
| out_free: |
| kfree(buf); |
| out: |
| return retval; |
| } |
| |
| static int cgroup_open(struct inode *inode, struct file *file) |
| { |
| struct pid *pid = PROC_I(inode)->pid; |
| return single_open(file, proc_cgroup_show, pid); |
| } |
| |
| const struct file_operations proc_cgroup_operations = { |
| .open = cgroup_open, |
| .read = seq_read, |
| .llseek = seq_lseek, |
| .release = single_release, |
| }; |
| |
| /* Display information about each subsystem and each hierarchy */ |
| static int proc_cgroupstats_show(struct seq_file *m, void *v) |
| { |
| 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 (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| struct cgroup_subsys *ss = subsys[i]; |
| if (ss == NULL) |
| continue; |
| seq_printf(m, "%s\t%d\t%d\t%d\n", |
| ss->name, ss->root->hierarchy_id, |
| ss->root->number_of_cgroups, !ss->disabled); |
| } |
| 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 - attach newly forked task to its parents cgroup. |
| * @child: pointer to task_struct of forking parent process. |
| * |
| * Description: A task inherits its parent's cgroup at fork(). |
| * |
| * A pointer to the shared css_set was automatically copied in |
| * fork.c by dup_task_struct(). However, we ignore that copy, since |
| * it was not made under the protection of RCU or cgroup_mutex, so |
| * might no longer be a valid cgroup pointer. cgroup_attach_task() might |
| * have already changed current->cgroups, allowing the previously |
| * referenced cgroup group to be removed and freed. |
| * |
| * At the point that cgroup_fork() is called, 'current' is the parent |
| * task, and the passed argument 'child' points to the child task. |
| */ |
| void cgroup_fork(struct task_struct *child) |
| { |
| task_lock(current); |
| child->cgroups = current->cgroups; |
| get_css_set(child->cgroups); |
| task_unlock(current); |
| INIT_LIST_HEAD(&child->cg_list); |
| } |
| |
| /** |
| * 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_iter_start() - to guarantee that the new task ends up on its |
| * list. |
| */ |
| void cgroup_post_fork(struct task_struct *child) |
| { |
| int i; |
| |
| /* |
| * use_task_css_set_links is set to 1 before we walk the tasklist |
| * under the tasklist_lock and we read it here after we added the child |
| * to the tasklist under the tasklist_lock as well. If the child wasn't |
| * yet in the tasklist when we walked through it from |
| * cgroup_enable_task_cg_lists(), then use_task_css_set_links value |
| * should be visible now due to the paired locking and barriers implied |
| * by LOCK/UNLOCK: it is written before the tasklist_lock unlock |
| * in cgroup_enable_task_cg_lists() and read here after the tasklist_lock |
| * lock on fork. |
| */ |
| if (use_task_css_set_links) { |
| write_lock(&css_set_lock); |
| task_lock(child); |
| if (list_empty(&child->cg_list)) |
| list_add(&child->cg_list, &child->cgroups->tasks); |
| task_unlock(child); |
| write_unlock(&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. |
| */ |
| if (need_forkexit_callback) { |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| struct cgroup_subsys *ss = subsys[i]; |
| |
| /* |
| * fork/exit callbacks are supported only for |
| * builtin subsystems and we don't need further |
| * synchronization as they never go away. |
| */ |
| if (!ss || ss->module) |
| continue; |
| |
| if (ss->fork) |
| ss->fork(child); |
| } |
| } |
| } |
| |
| /** |
| * cgroup_exit - detach cgroup from exiting task |
| * @tsk: pointer to task_struct of exiting process |
| * @run_callback: run exit callbacks? |
| * |
| * 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. |
| * |
| * the_top_cgroup_hack: |
| * |
| * 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. |
| * |
| * To do this properly, we would increment the reference count on |
| * top_cgroup, and near the very end of the kernel/exit.c do_exit() |
| * code we would add a second cgroup function call, to drop that |
| * reference. This would just create an unnecessary hot spot on |
| * the top_cgroup reference count, to no avail. |
| * |
| * Normally, holding a reference to a cgroup without bumping its |
| * count is unsafe. The cgroup could go away, or someone could |
| * attach us to a different cgroup, decrementing the count on |
| * the first cgroup that we never incremented. But in this case, |
| * top_cgroup isn't going away, and either task has PF_EXITING set, |
| * which wards off any cgroup_attach_task() attempts, or task is a failed |
| * fork, never visible to cgroup_attach_task. |
| */ |
| void cgroup_exit(struct task_struct *tsk, int run_callbacks) |
| { |
| struct css_set *cg; |
| int i; |
| |
| /* |
| * Unlink from the css_set task list if necessary. |
| * Optimistically check cg_list before taking |
| * css_set_lock |
| */ |
| if (!list_empty(&tsk->cg_list)) { |
| write_lock(&css_set_lock); |
| if (!list_empty(&tsk->cg_list)) |
| list_del_init(&tsk->cg_list); |
| write_unlock(&css_set_lock); |
| } |
| |
| /* Reassign the task to the init_css_set. */ |
| task_lock(tsk); |
| cg = tsk->cgroups; |
| tsk->cgroups = &init_css_set; |
| |
| if (run_callbacks && need_forkexit_callback) { |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| struct cgroup_subsys *ss = subsys[i]; |
| |
| /* modular subsystems can't use callbacks */ |
| if (!ss || ss->module) |
| continue; |
| |
| if (ss->exit) { |
| struct cgroup *old_cgrp = |
| rcu_dereference_raw(cg->subsys[i])->cgroup; |
| struct cgroup *cgrp = task_cgroup(tsk, i); |
| ss->exit(cgrp, old_cgrp, tsk); |
| } |
| } |
| } |
| task_unlock(tsk); |
| |
| put_css_set_taskexit(cg); |
| } |
| |
| /** |
| * cgroup_is_descendant - see if @cgrp is a descendant of @task's cgrp |
| * @cgrp: the cgroup in question |
| * @task: the task in question |
| * |
| * See if @cgrp is a descendant of @task's cgroup in the appropriate |
| * hierarchy. |
| * |
| * If we are sending in dummytop, then presumably we are creating |
| * the top cgroup in the subsystem. |
| * |
| * Called only by the ns (nsproxy) cgroup. |
| */ |
| int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task) |
| { |
| int ret; |
| struct cgroup *target; |
| |
| if (cgrp == dummytop) |
| return 1; |
| |
| target = task_cgroup_from_root(task, cgrp->root); |
| while (cgrp != target && cgrp!= cgrp->top_cgroup) |
| cgrp = cgrp->parent; |
| ret = (cgrp == target); |
| return ret; |
| } |
| |
| static void check_for_release(struct cgroup *cgrp) |
| { |
| /* All of these checks rely on RCU to keep the cgroup |
| * structure alive */ |
| if (cgroup_is_releasable(cgrp) && !atomic_read(&cgrp->count) |
| && list_empty(&cgrp->children) && !cgroup_has_css_refs(cgrp)) { |
| /* Control Group is currently removeable. If it's not |
| * already queued for a userspace notification, queue |
| * it now */ |
| int need_schedule_work = 0; |
| raw_spin_lock(&release_list_lock); |
| if (!cgroup_is_removed(cgrp) && |
| list_empty(&cgrp->release_list)) { |
| list_add(&cgrp->release_list, &release_list); |
| need_schedule_work = 1; |
| } |
| raw_spin_unlock(&release_list_lock); |
| if (need_schedule_work) |
| schedule_work(&release_agent_work); |
| } |
| } |
| |
| /* Caller must verify that the css is not for root cgroup */ |
| bool __css_tryget(struct cgroup_subsys_state *css) |
| { |
| while (true) { |
| int t, v; |
| |
| v = css_refcnt(css); |
| t = atomic_cmpxchg(&css->refcnt, v, v + 1); |
| if (likely(t == v)) |
| return true; |
| else if (t < 0) |
| return false; |
| cpu_relax(); |
| } |
| } |
| EXPORT_SYMBOL_GPL(__css_tryget); |
| |
| /* Caller must verify that the css is not for root cgroup */ |
| void __css_put(struct cgroup_subsys_state *css) |
| { |
| struct cgroup *cgrp = css->cgroup; |
| int v; |
| |
| rcu_read_lock(); |
| v = css_unbias_refcnt(atomic_dec_return(&css->refcnt)); |
| |
| switch (v) { |
| case 1: |
| if (notify_on_release(cgrp)) { |
| set_bit(CGRP_RELEASABLE, &cgrp->flags); |
| check_for_release(cgrp); |
| } |
| break; |
| case 0: |
| schedule_work(&css->dput_work); |
| break; |
| } |
| rcu_read_unlock(); |
| } |
| EXPORT_SYMBOL_GPL(__css_put); |
| |
| /* |
| * 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) |
| { |
| BUG_ON(work != &release_agent_work); |
| mutex_lock(&cgroup_mutex); |
| raw_spin_lock(&release_list_lock); |
| while (!list_empty(&release_list)) { |
| char *argv[3], *envp[3]; |
| int i; |
| char *pathbuf = NULL, *agentbuf = NULL; |
| struct cgroup *cgrp = list_entry(release_list.next, |
| struct cgroup, |
| release_list); |
| list_del_init(&cgrp->release_list); |
| raw_spin_unlock(&release_list_lock); |
| pathbuf = kmalloc(PAGE_SIZE, GFP_KERNEL); |
| if (!pathbuf) |
| goto continue_free; |
| if (cgroup_path(cgrp, pathbuf, PAGE_SIZE) < 0) |
| goto continue_free; |
| agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); |
| if (!agentbuf) |
| goto continue_free; |
| |
| i = 0; |
| argv[i++] = agentbuf; |
| argv[i++] = pathbuf; |
| argv[i] = NULL; |
| |
| i = 0; |
| /* minimal command environment */ |
| envp[i++] = "HOME=/"; |
| envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; |
| envp[i] = NULL; |
| |
| /* Drop the lock while we invoke the usermode helper, |
| * since the exec could involve hitting disk and hence |
| * be a slow process */ |
| mutex_unlock(&cgroup_mutex); |
| call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); |
| mutex_lock(&cgroup_mutex); |
| continue_free: |
| kfree(pathbuf); |
| kfree(agentbuf); |
| raw_spin_lock(&release_list_lock); |
| } |
| raw_spin_unlock(&release_list_lock); |
| mutex_unlock(&cgroup_mutex); |
| } |
| |
| static int __init cgroup_disable(char *str) |
| { |
| int i; |
| char *token; |
| |
| while ((token = strsep(&str, ",")) != NULL) { |
| if (!*token) |
| continue; |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| struct cgroup_subsys *ss = subsys[i]; |
| |
| /* |
| * cgroup_disable, being at boot time, can't |
| * know about module subsystems, so we don't |
| * worry about them. |
| */ |
| if (!ss || ss->module) |
| continue; |
| |
| if (!strcmp(token, ss->name)) { |
| ss->disabled = 1; |
| printk(KERN_INFO "Disabling %s control group" |
| " subsystem\n", ss->name); |
| break; |
| } |
| } |
| } |
| return 1; |
| } |
| __setup("cgroup_disable=", cgroup_disable); |
| |
| /* |
| * Functons for CSS ID. |
| */ |
| |
| /* |
| *To get ID other than 0, this should be called when !cgroup_is_removed(). |
| */ |
| unsigned short css_id(struct cgroup_subsys_state *css) |
| { |
| struct css_id *cssid; |
| |
| /* |
| * This css_id() can return correct value when somone has refcnt |
| * on this or this is under rcu_read_lock(). Once css->id is allocated, |
| * it's unchanged until freed. |
| */ |
| cssid = rcu_dereference_check(css->id, css_refcnt(css)); |
| |
| if (cssid) |
| return cssid->id; |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(css_id); |
| |
| unsigned short css_depth(struct cgroup_subsys_state *css) |
| { |
| struct css_id *cssid; |
| |
| cssid = rcu_dereference_check(css->id, css_refcnt(css)); |
| |
| if (cssid) |
| return cssid->depth; |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(css_depth); |
| |
| /** |
| * css_is_ancestor - test "root" css is an ancestor of "child" |
| * @child: the css to be tested. |
| * @root: the css supporsed to be an ancestor of the child. |
| * |
| * Returns true if "root" is an ancestor of "child" in its hierarchy. Because |
| * this function reads css->id, the caller must hold rcu_read_lock(). |
| * But, considering usual usage, the csses should be valid objects after test. |
| * Assuming that the caller will do some action to the child if this returns |
| * returns true, the caller must take "child";s reference count. |
| * If "child" is valid object and this returns true, "root" is valid, too. |
| */ |
| |
| bool css_is_ancestor(struct cgroup_subsys_state *child, |
| const struct cgroup_subsys_state *root) |
| { |
| struct css_id *child_id; |
| struct css_id *root_id; |
| |
| child_id = rcu_dereference(child->id); |
| if (!child_id) |
| return false; |
| root_id = rcu_dereference(root->id); |
| if (!root_id) |
| return false; |
| if (child_id->depth < root_id->depth) |
| return false; |
| if (child_id->stack[root_id->depth] != root_id->id) |
| return false; |
| return true; |
| } |
| |
| void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css) |
| { |
| struct css_id *id = css->id; |
| /* When this is called before css_id initialization, id can be NULL */ |
| if (!id) |
| return; |
| |
| BUG_ON(!ss->use_id); |
| |
| rcu_assign_pointer(id->css, NULL); |
| rcu_assign_pointer(css->id, NULL); |
| spin_lock(&ss->id_lock); |
| idr_remove(&ss->idr, id->id); |
| spin_unlock(&ss->id_lock); |
| kfree_rcu(id, rcu_head); |
| } |
| EXPORT_SYMBOL_GPL(free_css_id); |
| |
| /* |
| * This is called by init or create(). Then, calls to this function are |
| * always serialized (By cgroup_mutex() at create()). |
| */ |
| |
| static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth) |
| { |
| struct css_id *newid; |
| int ret, size; |
| |
| BUG_ON(!ss->use_id); |
| |
| size = sizeof(*newid) + sizeof(unsigned short) * (depth + 1); |
| newid = kzalloc(size, GFP_KERNEL); |
| if (!newid) |
| return ERR_PTR(-ENOMEM); |
| |
| idr_preload(GFP_KERNEL); |
| spin_lock(&ss->id_lock); |
| /* Don't use 0. allocates an ID of 1-65535 */ |
| ret = idr_alloc(&ss->idr, newid, 1, CSS_ID_MAX + 1, GFP_NOWAIT); |
| spin_unlock(&ss->id_lock); |
| idr_preload_end(); |
| |
| /* Returns error when there are no free spaces for new ID.*/ |
| if (ret < 0) |
| goto err_out; |
| |
| newid->id = ret; |
| newid->depth = depth; |
| return newid; |
| err_out: |
| kfree(newid); |
| return ERR_PTR(ret); |
| |
| } |
| |
| static int __init_or_module cgroup_init_idr(struct cgroup_subsys *ss, |
| struct cgroup_subsys_state *rootcss) |
| { |
| struct css_id *newid; |
| |
| spin_lock_init(&ss->id_lock); |
| idr_init(&ss->idr); |
| |
| newid = get_new_cssid(ss, 0); |
| if (IS_ERR(newid)) |
| return PTR_ERR(newid); |
| |
| newid->stack[0] = newid->id; |
| newid->css = rootcss; |
| rootcss->id = newid; |
| return 0; |
| } |
| |
| static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent, |
| struct cgroup *child) |
| { |
| int subsys_id, i, depth = 0; |
| struct cgroup_subsys_state *parent_css, *child_css; |
| struct css_id *child_id, *parent_id; |
| |
| subsys_id = ss->subsys_id; |
| parent_css = parent->subsys[subsys_id]; |
| child_css = child->subsys[subsys_id]; |
| parent_id = parent_css->id; |
| depth = parent_id->depth + 1; |
| |
| child_id = get_new_cssid(ss, depth); |
| if (IS_ERR(child_id)) |
| return PTR_ERR(child_id); |
| |
| for (i = 0; i < depth; i++) |
| child_id->stack[i] = parent_id->stack[i]; |
| child_id->stack[depth] = child_id->id; |
| /* |
| * child_id->css pointer will be set after this cgroup is available |
| * see cgroup_populate_dir() |
| */ |
| rcu_assign_pointer(child_css->id, child_id); |
| |
| return 0; |
| } |
| |
| /** |
| * css_lookup - lookup css by id |
| * @ss: cgroup subsys to be looked into. |
| * @id: the id |
| * |
| * Returns pointer to cgroup_subsys_state if there is valid one with id. |
| * NULL if not. Should be called under rcu_read_lock() |
| */ |
| struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id) |
| { |
| struct css_id *cssid = NULL; |
| |
| BUG_ON(!ss->use_id); |
| cssid = idr_find(&ss->idr, id); |
| |
| if (unlikely(!cssid)) |
| return NULL; |
| |
| return rcu_dereference(cssid->css); |
| } |
| EXPORT_SYMBOL_GPL(css_lookup); |
| |
| /** |
| * css_get_next - lookup next cgroup under specified hierarchy. |
| * @ss: pointer to subsystem |
| * @id: current position of iteration. |
| * @root: pointer to css. search tree under this. |
| * @foundid: position of found object. |
| * |
| * Search next css under the specified hierarchy of rootid. Calling under |
| * rcu_read_lock() is necessary. Returns NULL if it reaches the end. |
| */ |
| struct cgroup_subsys_state * |
| css_get_next(struct cgroup_subsys *ss, int id, |
| struct cgroup_subsys_state *root, int *foundid) |
| { |
| struct cgroup_subsys_state *ret = NULL; |
| struct css_id *tmp; |
| int tmpid; |
| int rootid = css_id(root); |
| int depth = css_depth(root); |
| |
| if (!rootid) |
| return NULL; |
| |
| BUG_ON(!ss->use_id); |
| WARN_ON_ONCE(!rcu_read_lock_held()); |
| |
| /* fill start point for scan */ |
| tmpid = id; |
| while (1) { |
| /* |
| * scan next entry from bitmap(tree), tmpid is updated after |
| * idr_get_next(). |
| */ |
| tmp = idr_get_next(&ss->idr, &tmpid); |
| if (!tmp) |
| break; |
| if (tmp->depth >= depth && tmp->stack[depth] == rootid) { |
| ret = rcu_dereference(tmp->css); |
| if (ret) { |
| *foundid = tmpid; |
| break; |
| } |
| } |
| /* continue to scan from next id */ |
| tmpid = tmpid + 1; |
| } |
| return ret; |
| } |
| |
| /* |
| * get corresponding css from file open on cgroupfs directory |
| */ |
| struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id) |
| { |
| struct cgroup *cgrp; |
| struct inode *inode; |
| struct cgroup_subsys_state *css; |
| |
| inode = file_inode(f); |
| /* check in cgroup filesystem dir */ |
| if (inode->i_op != &cgroup_dir_inode_operations) |
| return ERR_PTR(-EBADF); |
| |
| if (id < 0 || id >= CGROUP_SUBSYS_COUNT) |
| return ERR_PTR(-EINVAL); |
| |
| /* get cgroup */ |
| cgrp = __d_cgrp(f->f_dentry); |
| css = cgrp->subsys[id]; |
| return css ? css : ERR_PTR(-ENOENT); |
| } |
| |
| #ifdef CONFIG_CGROUP_DEBUG |
| static struct cgroup_subsys_state *debug_css_alloc(struct cgroup *cont) |
| { |
| 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 *cont) |
| { |
| kfree(cont->subsys[debug_subsys_id]); |
| } |
| |
| static u64 cgroup_refcount_read(struct cgroup *cont, struct cftype *cft) |
| { |
| return atomic_read(&cont->count); |
| } |
| |
| static u64 debug_taskcount_read(struct cgroup *cont, struct cftype *cft) |
| { |
| return cgroup_task_count(cont); |
| } |
| |
| static u64 current_css_set_read(struct cgroup *cont, struct cftype *cft) |
| { |
| return (u64)(unsigned long)current->cgroups; |
| } |
| |
| static u64 current_css_set_refcount_read(struct cgroup *cont, |
| struct cftype *cft) |
| { |
| u64 count; |
| |
| rcu_read_lock(); |
| count = atomic_read(¤t->cgroups->refcount); |
| rcu_read_unlock(); |
| return count; |
| } |
| |
| static int current_css_set_cg_links_read(struct cgroup *cont, |
| struct cftype *cft, |
| struct seq_file *seq) |
| { |
| struct cg_cgroup_link *link; |
| struct css_set *cg; |
| |
| read_lock(&css_set_lock); |
| rcu_read_lock(); |
| cg = rcu_dereference(current->cgroups); |
| list_for_each_entry(link, &cg->cg_links, cg_link_list) { |
| struct cgroup *c = link->cgrp; |
| const char *name; |
| |
| if (c->dentry) |
| name = c->dentry->d_name.name; |
| else |
| name = "?"; |
| seq_printf(seq, "Root %d group %s\n", |
| c->root->hierarchy_id, name); |
| } |
| rcu_read_unlock(); |
| read_unlock(&css_set_lock); |
| return 0; |
| } |
| |
| #define MAX_TASKS_SHOWN_PER_CSS 25 |
| static int cgroup_css_links_read(struct cgroup *cont, |
| struct cftype *cft, |
| struct seq_file *seq) |
| { |
| struct cg_cgroup_link *link; |
| |
| read_lock(&css_set_lock); |
| list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { |
| struct css_set *cg = link->cg; |
| struct task_struct *task; |
| int count = 0; |
| seq_printf(seq, "css_set %p\n", cg); |
| list_for_each_entry(task, &cg->tasks, cg_list) { |
| if (count++ > MAX_TASKS_SHOWN_PER_CSS) { |
| seq_puts(seq, " ...\n"); |
| break; |
| } else { |
| seq_printf(seq, " task %d\n", |
| task_pid_vnr(task)); |
| } |
| } |
| } |
| read_unlock(&css_set_lock); |
| return 0; |
| } |
| |
| static u64 releasable_read(struct cgroup *cgrp, struct cftype *cft) |
| { |
| return test_bit(CGRP_RELEASABLE, &cgrp->flags); |
| } |
| |
| static struct cftype debug_files[] = { |
| { |
| .name = "cgroup_refcount", |
| .read_u64 = cgroup_refcount_read, |
| }, |
| { |
| .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", |
| .read_seq_string = current_css_set_cg_links_read, |
| }, |
| |
| { |
| .name = "cgroup_css_links", |
| .read_seq_string = cgroup_css_links_read, |
| }, |
| |
| { |
| .name = "releasable", |
| .read_u64 = releasable_read, |
| }, |
| |
| { } /* terminate */ |
| }; |
| |
| struct cgroup_subsys debug_subsys = { |
| .name = "debug", |
| .css_alloc = debug_css_alloc, |
| .css_free = debug_css_free, |
| .subsys_id = debug_subsys_id, |
| .base_cftypes = debug_files, |
| }; |
| #endif /* CONFIG_CGROUP_DEBUG */ |