| /* |
| * Generic process-grouping system. |
| * |
| * Based originally on the cpuset system, extracted by Paul Menage |
| * Copyright (C) 2006 Google, Inc |
| * |
| * 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/errno.h> |
| #include <linux/fs.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/delayacct.h> |
| #include <linux/cgroupstats.h> |
| #include <linux/hash.h> |
| #include <linux/namei.h> |
| |
| #include <asm/atomic.h> |
| |
| static DEFINE_MUTEX(cgroup_mutex); |
| |
| /* Generate an array of cgroup subsystem pointers */ |
| #define SUBSYS(_x) &_x ## _subsys, |
| |
| static struct cgroup_subsys *subsys[] = { |
| #include <linux/cgroup_subsys.h> |
| }; |
| |
| /* |
| * 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_bits; |
| |
| /* The bitmask of subsystems currently attached to this hierarchy */ |
| unsigned long actual_subsys_bits; |
| |
| /* 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 mounted hierarchies */ |
| struct list_head root_list; |
| |
| /* Hierarchy-specific flags */ |
| unsigned long flags; |
| |
| /* The path to use for release notifications. */ |
| char release_agent_path[PATH_MAX]; |
| }; |
| |
| |
| /* |
| * 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; |
| |
| /* The list of hierarchy roots */ |
| |
| static LIST_HEAD(roots); |
| static int root_count; |
| |
| /* 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 need_mm_owner_callback __read_mostly; |
| |
| /* 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 */ |
| }; |
| |
| 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_root() allows you to iterate across the active hierarchies */ |
| #define for_each_root(_root) \ |
| list_for_each_entry(_root, &roots, root_list) |
| |
| /* the list of cgroups eligible for automatic release. Protected by |
| * release_list_lock */ |
| static LIST_HEAD(release_list); |
| static DEFINE_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; |
| /* |
| * 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; |
| |
| /* 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 */ |
| #define CSS_SET_HASH_BITS 7 |
| #define CSS_SET_TABLE_SIZE (1 << CSS_SET_HASH_BITS) |
| static struct hlist_head css_set_table[CSS_SET_TABLE_SIZE]; |
| |
| static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[]) |
| { |
| int i; |
| int index; |
| unsigned long tmp = 0UL; |
| |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) |
| tmp += (unsigned long)css[i]; |
| tmp = (tmp >> 16) ^ tmp; |
| |
| index = hash_long(tmp, CSS_SET_HASH_BITS); |
| |
| return &css_set_table[index]; |
| } |
| |
| /* 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; |
| |
| /* When we create or destroy a css_set, the operation simply |
| * takes/releases a reference count on all the cgroups referenced |
| * by subsystems in this css_set. This can end up multiple-counting |
| * some cgroups, but that's OK - the ref-count is just a |
| * busy/not-busy indicator; ensuring that we only count each cgroup |
| * once would require taking a global lock to ensure that no |
| * subsystems moved between hierarchies while we were doing so. |
| * |
| * Possible TODO: decide at boot time based on the number of |
| * registered subsystems and the number of CPUs or NUMA nodes whether |
| * it's better for performance to ref-count every subsystem, or to |
| * take a global lock and only add one ref count to each hierarchy. |
| */ |
| |
| /* |
| * unlink a css_set from the list and free it |
| */ |
| static void unlink_css_set(struct css_set *cg) |
| { |
| struct cg_cgroup_link *link; |
| struct cg_cgroup_link *saved_link; |
| |
| hlist_del(&cg->hlist); |
| css_set_count--; |
| |
| list_for_each_entry_safe(link, saved_link, &cg->cg_links, |
| cg_link_list) { |
| list_del(&link->cg_link_list); |
| list_del(&link->cgrp_link_list); |
| kfree(link); |
| } |
| } |
| |
| static void __put_css_set(struct css_set *cg, int taskexit) |
| { |
| int i; |
| /* |
| * 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; |
| } |
| unlink_css_set(cg); |
| write_unlock(&css_set_lock); |
| |
| rcu_read_lock(); |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| struct cgroup *cgrp = cg->subsys[i]->cgroup; |
| 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(cg); |
| } |
| |
| /* |
| * 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); |
| } |
| |
| /* |
| * 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 hlist_head *hhead; |
| struct hlist_node *node; |
| struct css_set *cg; |
| |
| /* Built the set of subsystem state objects that we want to |
| * see in the new css_set */ |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| if (root->subsys_bits & (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]; |
| } |
| } |
| |
| hhead = css_set_hash(template); |
| hlist_for_each_entry(cg, node, hhead, hlist) { |
| if (!memcmp(template, cg->subsys, sizeof(cg->subsys))) { |
| /* All subsystems matched */ |
| 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; |
| } |
| |
| /* |
| * 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]; |
| int i; |
| |
| struct list_head tmp_cg_links; |
| struct cg_cgroup_link *link; |
| |
| struct hlist_head *hhead; |
| |
| /* 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. */ |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| struct cgroup *cgrp = res->subsys[i]->cgroup; |
| struct cgroup_subsys *ss = subsys[i]; |
| atomic_inc(&cgrp->count); |
| /* |
| * We want to add a link once per cgroup, so we |
| * only do it for the first subsystem in each |
| * hierarchy |
| */ |
| if (ss->root->subsys_list.next == &ss->sibling) { |
| BUG_ON(list_empty(&tmp_cg_links)); |
| link = list_entry(tmp_cg_links.next, |
| struct cg_cgroup_link, |
| cgrp_link_list); |
| list_del(&link->cgrp_link_list); |
| list_add(&link->cgrp_link_list, &cgrp->css_sets); |
| link->cg = res; |
| list_add(&link->cg_link_list, &res->cg_links); |
| } |
| } |
| if (list_empty(&rootnode.subsys_list)) { |
| link = list_entry(tmp_cg_links.next, |
| struct cg_cgroup_link, |
| cgrp_link_list); |
| list_del(&link->cgrp_link_list); |
| list_add(&link->cgrp_link_list, &dummytop->css_sets); |
| link->cg = res; |
| list_add(&link->cg_link_list, &res->cg_links); |
| } |
| |
| BUG_ON(!list_empty(&tmp_cg_links)); |
| |
| css_set_count++; |
| |
| /* Add this cgroup group to the hash table */ |
| hhead = css_set_hash(res->subsys); |
| hlist_add_head(&res->hlist, hhead); |
| |
| write_unlock(&css_set_lock); |
| |
| 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 tasks 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'ss 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); |
| } |
| |
| /** |
| * 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); |
| } |
| |
| /* |
| * 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, int mode); |
| static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry); |
| static int cgroup_populate_dir(struct cgroup *cgrp); |
| static struct inode_operations cgroup_dir_inode_operations; |
| static struct file_operations proc_cgroupstats_operations; |
| |
| static struct backing_dev_info cgroup_backing_dev_info = { |
| .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, |
| }; |
| |
| static struct inode *cgroup_new_inode(mode_t mode, struct super_block *sb) |
| { |
| struct inode *inode = new_inode(sb); |
| |
| if (inode) { |
| 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; |
| } |
| |
| /* |
| * Call subsys's pre_destroy handler. |
| * This is called before css refcnt check. |
| */ |
| static void cgroup_call_pre_destroy(struct cgroup *cgrp) |
| { |
| struct cgroup_subsys *ss; |
| for_each_subsys(cgrp->root, ss) |
| if (ss->pre_destroy && cgrp->subsys[ss->subsys_id]) |
| ss->pre_destroy(ss, cgrp); |
| return; |
| } |
| |
| 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; |
| struct cgroup_subsys *ss; |
| BUG_ON(!(cgroup_is_removed(cgrp))); |
| /* It's possible for external users to be holding css |
| * reference counts on a cgroup; css_put() needs to |
| * be able to access the cgroup after decrementing |
| * the reference count in order to know if it needs to |
| * queue the cgroup to be handled by the release |
| * agent */ |
| synchronize_rcu(); |
| |
| mutex_lock(&cgroup_mutex); |
| /* |
| * Release the subsystem state objects. |
| */ |
| for_each_subsys(cgrp->root, ss) { |
| if (cgrp->subsys[ss->subsys_id]) |
| ss->destroy(ss, 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); |
| |
| kfree(cgrp); |
| } |
| iput(inode); |
| } |
| |
| 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_clear_directory(struct dentry *dentry) |
| { |
| struct list_head *node; |
| |
| BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex)); |
| spin_lock(&dcache_lock); |
| node = dentry->d_subdirs.next; |
| while (node != &dentry->d_subdirs) { |
| struct dentry *d = list_entry(node, struct dentry, d_u.d_child); |
| list_del_init(node); |
| if (d->d_inode) { |
| /* This should never be called on a cgroup |
| * directory with child cgroups */ |
| BUG_ON(d->d_inode->i_mode & S_IFDIR); |
| d = dget_locked(d); |
| spin_unlock(&dcache_lock); |
| d_delete(d); |
| simple_unlink(dentry->d_inode, d); |
| dput(d); |
| spin_lock(&dcache_lock); |
| } |
| node = dentry->d_subdirs.next; |
| } |
| spin_unlock(&dcache_lock); |
| } |
| |
| /* |
| * NOTE : the dentry must have been dget()'ed |
| */ |
| static void cgroup_d_remove_dir(struct dentry *dentry) |
| { |
| cgroup_clear_directory(dentry); |
| |
| spin_lock(&dcache_lock); |
| list_del_init(&dentry->d_u.d_child); |
| spin_unlock(&dcache_lock); |
| remove_dir(dentry); |
| } |
| |
| static int rebind_subsystems(struct cgroupfs_root *root, |
| unsigned long final_bits) |
| { |
| unsigned long added_bits, removed_bits; |
| struct cgroup *cgrp = &root->top_cgroup; |
| int i; |
| |
| removed_bits = root->actual_subsys_bits & ~final_bits; |
| added_bits = final_bits & ~root->actual_subsys_bits; |
| /* 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_bits)) |
| continue; |
| 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_bits) { |
| /* We're binding this subsystem to this hierarchy */ |
| 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_add(&ss->sibling, &root->subsys_list); |
| rcu_assign_pointer(ss->root, root); |
| if (ss->bind) |
| ss->bind(ss, cgrp); |
| |
| } else if (bit & removed_bits) { |
| /* We're removing this subsystem */ |
| BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]); |
| BUG_ON(cgrp->subsys[i]->cgroup != cgrp); |
| if (ss->bind) |
| ss->bind(ss, dummytop); |
| dummytop->subsys[i]->cgroup = dummytop; |
| cgrp->subsys[i] = NULL; |
| rcu_assign_pointer(subsys[i]->root, &rootnode); |
| list_del(&ss->sibling); |
| } else if (bit & final_bits) { |
| /* Subsystem state should already exist */ |
| BUG_ON(!cgrp->subsys[i]); |
| } else { |
| /* Subsystem state shouldn't exist */ |
| BUG_ON(cgrp->subsys[i]); |
| } |
| } |
| root->subsys_bits = root->actual_subsys_bits = final_bits; |
| synchronize_rcu(); |
| |
| return 0; |
| } |
| |
| static int cgroup_show_options(struct seq_file *seq, struct vfsmount *vfs) |
| { |
| struct cgroupfs_root *root = vfs->mnt_sb->s_fs_info; |
| struct cgroup_subsys *ss; |
| |
| mutex_lock(&cgroup_mutex); |
| for_each_subsys(root, ss) |
| seq_printf(seq, ",%s", ss->name); |
| if (test_bit(ROOT_NOPREFIX, &root->flags)) |
| seq_puts(seq, ",noprefix"); |
| if (strlen(root->release_agent_path)) |
| seq_printf(seq, ",release_agent=%s", root->release_agent_path); |
| mutex_unlock(&cgroup_mutex); |
| return 0; |
| } |
| |
| struct cgroup_sb_opts { |
| unsigned long subsys_bits; |
| unsigned long flags; |
| char *release_agent; |
| }; |
| |
| /* Convert a hierarchy specifier into a bitmask of subsystems and |
| * flags. */ |
| static int parse_cgroupfs_options(char *data, |
| struct cgroup_sb_opts *opts) |
| { |
| char *token, *o = data ?: "all"; |
| |
| opts->subsys_bits = 0; |
| opts->flags = 0; |
| opts->release_agent = NULL; |
| |
| while ((token = strsep(&o, ",")) != NULL) { |
| if (!*token) |
| return -EINVAL; |
| if (!strcmp(token, "all")) { |
| /* Add all non-disabled subsystems */ |
| int i; |
| opts->subsys_bits = 0; |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| struct cgroup_subsys *ss = subsys[i]; |
| if (!ss->disabled) |
| opts->subsys_bits |= 1ul << i; |
| } |
| } else if (!strcmp(token, "noprefix")) { |
| set_bit(ROOT_NOPREFIX, &opts->flags); |
| } else if (!strncmp(token, "release_agent=", 14)) { |
| /* Specifying two release agents is forbidden */ |
| if (opts->release_agent) |
| return -EINVAL; |
| opts->release_agent = kzalloc(PATH_MAX, GFP_KERNEL); |
| if (!opts->release_agent) |
| return -ENOMEM; |
| strncpy(opts->release_agent, token + 14, PATH_MAX - 1); |
| opts->release_agent[PATH_MAX - 1] = 0; |
| } else { |
| struct cgroup_subsys *ss; |
| int i; |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| ss = subsys[i]; |
| if (!strcmp(token, ss->name)) { |
| if (!ss->disabled) |
| set_bit(i, &opts->subsys_bits); |
| break; |
| } |
| } |
| if (i == CGROUP_SUBSYS_COUNT) |
| return -ENOENT; |
| } |
| } |
| |
| /* We can't have an empty hierarchy */ |
| if (!opts->subsys_bits) |
| return -EINVAL; |
| |
| return 0; |
| } |
| |
| 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; |
| |
| mutex_lock(&cgrp->dentry->d_inode->i_mutex); |
| mutex_lock(&cgroup_mutex); |
| |
| /* See what subsystems are wanted */ |
| ret = parse_cgroupfs_options(data, &opts); |
| if (ret) |
| goto out_unlock; |
| |
| /* Don't allow flags to change at remount */ |
| if (opts.flags != root->flags) { |
| ret = -EINVAL; |
| goto out_unlock; |
| } |
| |
| ret = rebind_subsystems(root, opts.subsys_bits); |
| |
| /* (re)populate subsystem files */ |
| if (!ret) |
| cgroup_populate_dir(cgrp); |
| |
| if (opts.release_agent) |
| strcpy(root->release_agent_path, opts.release_agent); |
| out_unlock: |
| if (opts.release_agent) |
| kfree(opts.release_agent); |
| mutex_unlock(&cgroup_mutex); |
| mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
| return ret; |
| } |
| |
| static 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->css_sets); |
| INIT_LIST_HEAD(&cgrp->release_list); |
| init_rwsem(&cgrp->pids_mutex); |
| } |
| 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); |
| root->number_of_cgroups = 1; |
| cgrp->root = root; |
| cgrp->top_cgroup = cgrp; |
| init_cgroup_housekeeping(cgrp); |
| } |
| |
| static int cgroup_test_super(struct super_block *sb, void *data) |
| { |
| struct cgroupfs_root *new = data; |
| struct cgroupfs_root *root = sb->s_fs_info; |
| |
| /* First check subsystems */ |
| if (new->subsys_bits != root->subsys_bits) |
| return 0; |
| |
| /* Next check flags */ |
| if (new->flags != root->flags) |
| return 0; |
| |
| return 1; |
| } |
| |
| static int cgroup_set_super(struct super_block *sb, void *data) |
| { |
| int ret; |
| struct cgroupfs_root *root = data; |
| |
| ret = set_anon_super(sb, NULL); |
| if (ret) |
| return ret; |
| |
| sb->s_fs_info = root; |
| 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) |
| { |
| struct inode *inode = |
| cgroup_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR, sb); |
| struct dentry *dentry; |
| |
| 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); |
| dentry = d_alloc_root(inode); |
| if (!dentry) { |
| iput(inode); |
| return -ENOMEM; |
| } |
| sb->s_root = dentry; |
| return 0; |
| } |
| |
| static int cgroup_get_sb(struct file_system_type *fs_type, |
| int flags, const char *unused_dev_name, |
| void *data, struct vfsmount *mnt) |
| { |
| struct cgroup_sb_opts opts; |
| int ret = 0; |
| struct super_block *sb; |
| struct cgroupfs_root *root; |
| struct list_head tmp_cg_links; |
| |
| /* First find the desired set of subsystems */ |
| ret = parse_cgroupfs_options(data, &opts); |
| if (ret) { |
| if (opts.release_agent) |
| kfree(opts.release_agent); |
| return ret; |
| } |
| |
| root = kzalloc(sizeof(*root), GFP_KERNEL); |
| if (!root) { |
| if (opts.release_agent) |
| kfree(opts.release_agent); |
| return -ENOMEM; |
| } |
| |
| init_cgroup_root(root); |
| root->subsys_bits = opts.subsys_bits; |
| root->flags = opts.flags; |
| if (opts.release_agent) { |
| strcpy(root->release_agent_path, opts.release_agent); |
| kfree(opts.release_agent); |
| } |
| |
| sb = sget(fs_type, cgroup_test_super, cgroup_set_super, root); |
| |
| if (IS_ERR(sb)) { |
| kfree(root); |
| return PTR_ERR(sb); |
| } |
| |
| if (sb->s_fs_info != root) { |
| /* Reusing an existing superblock */ |
| BUG_ON(sb->s_root == NULL); |
| kfree(root); |
| root = NULL; |
| } else { |
| /* New superblock */ |
| struct cgroup *cgrp = &root->top_cgroup; |
| struct inode *inode; |
| int i; |
| |
| 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); |
| |
| /* |
| * 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) { |
| mutex_unlock(&cgroup_mutex); |
| mutex_unlock(&inode->i_mutex); |
| goto drop_new_super; |
| } |
| |
| ret = rebind_subsystems(root, root->subsys_bits); |
| if (ret == -EBUSY) { |
| mutex_unlock(&cgroup_mutex); |
| mutex_unlock(&inode->i_mutex); |
| goto free_cg_links; |
| } |
| |
| /* EBUSY should be the only error here */ |
| BUG_ON(ret); |
| |
| list_add(&root->root_list, &roots); |
| root_count++; |
| |
| sb->s_root->d_fsdata = &root->top_cgroup; |
| 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); |
| for (i = 0; i < CSS_SET_TABLE_SIZE; i++) { |
| struct hlist_head *hhead = &css_set_table[i]; |
| struct hlist_node *node; |
| struct css_set *cg; |
| |
| hlist_for_each_entry(cg, node, hhead, hlist) { |
| struct cg_cgroup_link *link; |
| |
| BUG_ON(list_empty(&tmp_cg_links)); |
| link = list_entry(tmp_cg_links.next, |
| struct cg_cgroup_link, |
| cgrp_link_list); |
| list_del(&link->cgrp_link_list); |
| link->cg = cg; |
| list_add(&link->cgrp_link_list, |
| &root->top_cgroup.css_sets); |
| list_add(&link->cg_link_list, &cg->cg_links); |
| } |
| } |
| write_unlock(&css_set_lock); |
| |
| free_cg_links(&tmp_cg_links); |
| |
| BUG_ON(!list_empty(&cgrp->sibling)); |
| BUG_ON(!list_empty(&cgrp->children)); |
| BUG_ON(root->number_of_cgroups != 1); |
| |
| cgroup_populate_dir(cgrp); |
| mutex_unlock(&inode->i_mutex); |
| mutex_unlock(&cgroup_mutex); |
| } |
| |
| return simple_set_mnt(mnt, sb); |
| |
| free_cg_links: |
| free_cg_links(&tmp_cg_links); |
| drop_new_super: |
| up_write(&sb->s_umount); |
| deactivate_super(sb); |
| return 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)); |
| BUG_ON(!list_empty(&cgrp->sibling)); |
| |
| mutex_lock(&cgroup_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_mutex); |
| |
| kfree(root); |
| kill_litter_super(sb); |
| } |
| |
| static struct file_system_type cgroup_fs_type = { |
| .name = "cgroup", |
| .get_sb = cgroup_get_sb, |
| .kill_sb = cgroup_kill_sb, |
| }; |
| |
| static inline struct cgroup *__d_cgrp(struct dentry *dentry) |
| { |
| return dentry->d_fsdata; |
| } |
| |
| static inline struct cftype *__d_cft(struct dentry *dentry) |
| { |
| return dentry->d_fsdata; |
| } |
| |
| /** |
| * 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. Writes path of cgroup into buf. |
| * Returns 0 on success, -errno on error. |
| */ |
| int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) |
| { |
| char *start; |
| |
| if (cgrp == dummytop) { |
| /* |
| * Inactive subsystems have no dentry for their root |
| * cgroup |
| */ |
| strcpy(buf, "/"); |
| return 0; |
| } |
| |
| start = buf + buflen; |
| |
| *--start = '\0'; |
| for (;;) { |
| int len = cgrp->dentry->d_name.len; |
| if ((start -= len) < buf) |
| return -ENAMETOOLONG; |
| memcpy(start, cgrp->dentry->d_name.name, len); |
| cgrp = cgrp->parent; |
| if (!cgrp) |
| break; |
| if (!cgrp->parent) |
| continue; |
| if (--start < buf) |
| return -ENAMETOOLONG; |
| *start = '/'; |
| } |
| memmove(buf, start, buf + buflen - start); |
| return 0; |
| } |
| |
| /* |
| * Return the first subsystem attached to a cgroup's hierarchy, and |
| * its subsystem id. |
| */ |
| |
| static void get_first_subsys(const struct cgroup *cgrp, |
| struct cgroup_subsys_state **css, int *subsys_id) |
| { |
| const struct cgroupfs_root *root = cgrp->root; |
| const struct cgroup_subsys *test_ss; |
| BUG_ON(list_empty(&root->subsys_list)); |
| test_ss = list_entry(root->subsys_list.next, |
| struct cgroup_subsys, sibling); |
| if (css) { |
| *css = cgrp->subsys[test_ss->subsys_id]; |
| BUG_ON(!*css); |
| } |
| if (subsys_id) |
| *subsys_id = test_ss->subsys_id; |
| } |
| |
| /** |
| * cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp' |
| * @cgrp: the cgroup the task is attaching to |
| * @tsk: the task to be attached |
| * |
| * Call holding cgroup_mutex. May take task_lock of |
| * the task 'tsk' during call. |
| */ |
| int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) |
| { |
| int retval = 0; |
| struct cgroup_subsys *ss; |
| struct cgroup *oldcgrp; |
| struct css_set *cg = tsk->cgroups; |
| struct css_set *newcg; |
| struct cgroupfs_root *root = cgrp->root; |
| int subsys_id; |
| |
| get_first_subsys(cgrp, NULL, &subsys_id); |
| |
| /* Nothing to do if the task is already in that cgroup */ |
| oldcgrp = task_cgroup(tsk, subsys_id); |
| if (cgrp == oldcgrp) |
| return 0; |
| |
| for_each_subsys(root, ss) { |
| if (ss->can_attach) { |
| retval = ss->can_attach(ss, cgrp, tsk); |
| if (retval) |
| return retval; |
| } |
| } |
| |
| /* |
| * Locate or allocate a new css_set for this task, |
| * based on its final set of cgroups |
| */ |
| newcg = find_css_set(cg, cgrp); |
| if (!newcg) |
| return -ENOMEM; |
| |
| task_lock(tsk); |
| if (tsk->flags & PF_EXITING) { |
| task_unlock(tsk); |
| put_css_set(newcg); |
| return -ESRCH; |
| } |
| 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_del(&tsk->cg_list); |
| list_add(&tsk->cg_list, &newcg->tasks); |
| } |
| write_unlock(&css_set_lock); |
| |
| for_each_subsys(root, ss) { |
| if (ss->attach) |
| ss->attach(ss, cgrp, oldcgrp, tsk); |
| } |
| set_bit(CGRP_RELEASABLE, &oldcgrp->flags); |
| synchronize_rcu(); |
| put_css_set(cg); |
| return 0; |
| } |
| |
| /* |
| * Attach task with pid 'pid' to cgroup 'cgrp'. Call with cgroup_mutex |
| * held. May take task_lock of task |
| */ |
| static int attach_task_by_pid(struct cgroup *cgrp, u64 pid) |
| { |
| struct task_struct *tsk; |
| const struct cred *cred = current_cred(), *tcred; |
| int ret; |
| |
| if (pid) { |
| rcu_read_lock(); |
| tsk = find_task_by_vpid(pid); |
| if (!tsk || tsk->flags & PF_EXITING) { |
| rcu_read_unlock(); |
| return -ESRCH; |
| } |
| |
| tcred = __task_cred(tsk); |
| if (cred->euid && |
| cred->euid != tcred->uid && |
| cred->euid != tcred->suid) { |
| rcu_read_unlock(); |
| return -EACCES; |
| } |
| get_task_struct(tsk); |
| rcu_read_unlock(); |
| } else { |
| tsk = current; |
| get_task_struct(tsk); |
| } |
| |
| ret = cgroup_attach_task(cgrp, tsk); |
| put_task_struct(tsk); |
| return ret; |
| } |
| |
| static int cgroup_tasks_write(struct cgroup *cgrp, struct cftype *cft, u64 pid) |
| { |
| int ret; |
| if (!cgroup_lock_live_group(cgrp)) |
| return -ENODEV; |
| ret = attach_task_by_pid(cgrp, pid); |
| cgroup_unlock(); |
| return ret; |
| } |
| |
| /* The various types of files and directories in a cgroup file system */ |
| enum cgroup_filetype { |
| FILE_ROOT, |
| FILE_DIR, |
| FILE_TASKLIST, |
| FILE_NOTIFY_ON_RELEASE, |
| FILE_RELEASE_AGENT, |
| }; |
| |
| /** |
| * 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; |
| } |
| |
| 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 (!cgroup_lock_live_group(cgrp)) |
| return -ENODEV; |
| strcpy(cgrp->root->release_agent_path, buffer); |
| 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 */ |
| strstrip(buffer); |
| if (cft->write_u64) { |
| u64 val = simple_strtoull(buffer, &end, 0); |
| if (*end) |
| return -EINVAL; |
| retval = cft->write_u64(cgrp, cft, val); |
| } else { |
| s64 val = simple_strtoll(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 */ |
| strstrip(buffer); |
| retval = cft->write_string(cgrp, cft, 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 (!cft || 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 (!cft || 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 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) |
| return -ENODEV; |
| 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 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 struct inode_operations cgroup_dir_inode_operations = { |
| .lookup = simple_lookup, |
| .mkdir = cgroup_mkdir, |
| .rmdir = cgroup_rmdir, |
| .rename = cgroup_rename, |
| }; |
| |
| static int cgroup_create_file(struct dentry *dentry, int mode, |
| struct super_block *sb) |
| { |
| static struct dentry_operations cgroup_dops = { |
| .d_iput = cgroup_diput, |
| }; |
| |
| 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); |
| |
| /* start with the directory inode held, so that we can |
| * populate it without racing with another mkdir */ |
| mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD); |
| } else if (S_ISREG(mode)) { |
| inode->i_size = 0; |
| inode->i_fop = &cgroup_file_operations; |
| } |
| dentry->d_op = &cgroup_dops; |
| d_instantiate(dentry, inode); |
| dget(dentry); /* Extra count - pin the dentry in core */ |
| return 0; |
| } |
| |
| /* |
| * cgroup_create_dir - create a directory for an object. |
| * @cgrp: the cgroup we create the directory for. It must have a valid |
| * ->parent field. And we are going to fill its ->dentry field. |
| * @dentry: dentry of the new cgroup |
| * @mode: mode to set on new directory. |
| */ |
| static int cgroup_create_dir(struct cgroup *cgrp, struct dentry *dentry, |
| int mode) |
| { |
| struct dentry *parent; |
| int error = 0; |
| |
| parent = cgrp->parent->dentry; |
| error = cgroup_create_file(dentry, S_IFDIR | mode, cgrp->root->sb); |
| if (!error) { |
| dentry->d_fsdata = cgrp; |
| inc_nlink(parent->d_inode); |
| cgrp->dentry = dentry; |
| dget(dentry); |
| } |
| dput(dentry); |
| |
| return error; |
| } |
| |
| int cgroup_add_file(struct cgroup *cgrp, |
| struct cgroup_subsys *subsys, |
| const struct cftype *cft) |
| { |
| struct dentry *dir = cgrp->dentry; |
| struct dentry *dentry; |
| int error; |
| |
| char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 }; |
| 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)); |
| dentry = lookup_one_len(name, dir, strlen(name)); |
| if (!IS_ERR(dentry)) { |
| error = cgroup_create_file(dentry, 0644 | S_IFREG, |
| cgrp->root->sb); |
| if (!error) |
| dentry->d_fsdata = (void *)cft; |
| dput(dentry); |
| } else |
| error = PTR_ERR(dentry); |
| return error; |
| } |
| |
| int cgroup_add_files(struct cgroup *cgrp, |
| struct cgroup_subsys *subsys, |
| const struct cftype cft[], |
| int count) |
| { |
| int i, err; |
| for (i = 0; i < count; i++) { |
| err = cgroup_add_file(cgrp, subsys, &cft[i]); |
| if (err) |
| return err; |
| } |
| return 0; |
| } |
| |
| /** |
| * 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(). |
| * |
| * The tasklist_lock is not held here, as do_each_thread() and |
| * while_each_thread() are protected by RCU. |
| */ |
| static void cgroup_enable_task_cg_lists(void) |
| { |
| struct task_struct *p, *g; |
| write_lock(&css_set_lock); |
| use_task_css_set_links = 1; |
| 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); |
| write_unlock(&css_set_lock); |
| } |
| |
| void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it) |
| { |
| /* |
| * 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; |
| |
| /* 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; |
| if (l == &res->cgroups->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) |
| { |
| 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' file. |
| * |
| * 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. |
| * |
| */ |
| |
| /* |
| * Load into 'pidarray' up to 'npids' of the tasks using cgroup |
| * 'cgrp'. Return actual number of pids loaded. No need to |
| * task_lock(p) when reading out p->cgroup, since we're in an RCU |
| * read section, so the css_set can't go away, and is |
| * immutable after creation. |
| */ |
| static int pid_array_load(pid_t *pidarray, int npids, struct cgroup *cgrp) |
| { |
| int n = 0; |
| struct cgroup_iter it; |
| struct task_struct *tsk; |
| cgroup_iter_start(cgrp, &it); |
| while ((tsk = cgroup_iter_next(cgrp, &it))) { |
| if (unlikely(n == npids)) |
| break; |
| pidarray[n++] = task_pid_vnr(tsk); |
| } |
| cgroup_iter_end(cgrp, &it); |
| return n; |
| } |
| |
| /** |
| * 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; |
| rcu_read_lock(); |
| |
| 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); |
| |
| rcu_read_unlock(); |
| err: |
| return ret; |
| } |
| |
| static int cmppid(const void *a, const void *b) |
| { |
| return *(pid_t *)a - *(pid_t *)b; |
| } |
| |
| |
| /* |
| * seq_file methods for the "tasks" file. The seq_file position is the |
| * next pid to display; the seq_file iterator is a pointer to the pid |
| * in the cgroup->tasks_pids array. |
| */ |
| |
| static void *cgroup_tasks_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 *cgrp = s->private; |
| int index = 0, pid = *pos; |
| int *iter; |
| |
| down_read(&cgrp->pids_mutex); |
| if (pid) { |
| int end = cgrp->pids_length; |
| |
| while (index < end) { |
| int mid = (index + end) / 2; |
| if (cgrp->tasks_pids[mid] == pid) { |
| index = mid; |
| break; |
| } else if (cgrp->tasks_pids[mid] <= pid) |
| index = mid + 1; |
| else |
| end = mid; |
| } |
| } |
| /* If we're off the end of the array, we're done */ |
| if (index >= cgrp->pids_length) |
| return NULL; |
| /* Update the abstract position to be the actual pid that we found */ |
| iter = cgrp->tasks_pids + index; |
| *pos = *iter; |
| return iter; |
| } |
| |
| static void cgroup_tasks_stop(struct seq_file *s, void *v) |
| { |
| struct cgroup *cgrp = s->private; |
| up_read(&cgrp->pids_mutex); |
| } |
| |
| static void *cgroup_tasks_next(struct seq_file *s, void *v, loff_t *pos) |
| { |
| struct cgroup *cgrp = s->private; |
| int *p = v; |
| int *end = cgrp->tasks_pids + cgrp->pids_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_tasks_show(struct seq_file *s, void *v) |
| { |
| return seq_printf(s, "%d\n", *(int *)v); |
| } |
| |
| static struct seq_operations cgroup_tasks_seq_operations = { |
| .start = cgroup_tasks_start, |
| .stop = cgroup_tasks_stop, |
| .next = cgroup_tasks_next, |
| .show = cgroup_tasks_show, |
| }; |
| |
| static void release_cgroup_pid_array(struct cgroup *cgrp) |
| { |
| down_write(&cgrp->pids_mutex); |
| BUG_ON(!cgrp->pids_use_count); |
| if (!--cgrp->pids_use_count) { |
| kfree(cgrp->tasks_pids); |
| cgrp->tasks_pids = NULL; |
| cgrp->pids_length = 0; |
| } |
| up_write(&cgrp->pids_mutex); |
| } |
| |
| static int cgroup_tasks_release(struct inode *inode, struct file *file) |
| { |
| struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
| |
| if (!(file->f_mode & FMODE_READ)) |
| return 0; |
| |
| release_cgroup_pid_array(cgrp); |
| return seq_release(inode, file); |
| } |
| |
| static struct file_operations cgroup_tasks_operations = { |
| .read = seq_read, |
| .llseek = seq_lseek, |
| .write = cgroup_file_write, |
| .release = cgroup_tasks_release, |
| }; |
| |
| /* |
| * Handle an open on 'tasks' file. Prepare an array containing the |
| * process id's of tasks currently attached to the cgroup being opened. |
| */ |
| |
| static int cgroup_tasks_open(struct inode *unused, struct file *file) |
| { |
| struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
| pid_t *pidarray; |
| int npids; |
| int retval; |
| |
| /* Nothing to do for write-only files */ |
| if (!(file->f_mode & FMODE_READ)) |
| return 0; |
| |
| /* |
| * 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. |
| */ |
| npids = cgroup_task_count(cgrp); |
| pidarray = kmalloc(npids * sizeof(pid_t), GFP_KERNEL); |
| if (!pidarray) |
| return -ENOMEM; |
| npids = pid_array_load(pidarray, npids, cgrp); |
| sort(pidarray, npids, sizeof(pid_t), cmppid, NULL); |
| |
| /* |
| * Store the array in the cgroup, freeing the old |
| * array if necessary |
| */ |
| down_write(&cgrp->pids_mutex); |
| kfree(cgrp->tasks_pids); |
| cgrp->tasks_pids = pidarray; |
| cgrp->pids_length = npids; |
| cgrp->pids_use_count++; |
| up_write(&cgrp->pids_mutex); |
| |
| file->f_op = &cgroup_tasks_operations; |
| |
| retval = seq_open(file, &cgroup_tasks_seq_operations); |
| if (retval) { |
| release_cgroup_pid_array(cgrp); |
| return retval; |
| } |
| ((struct seq_file *)file->private_data)->private = cgrp; |
| return 0; |
| } |
| |
| 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; |
| } |
| |
| /* |
| * for the common functions, 'private' gives the type of file |
| */ |
| static struct cftype files[] = { |
| { |
| .name = "tasks", |
| .open = cgroup_tasks_open, |
| .write_u64 = cgroup_tasks_write, |
| .release = cgroup_tasks_release, |
| .private = FILE_TASKLIST, |
| }, |
| |
| { |
| .name = "notify_on_release", |
| .read_u64 = cgroup_read_notify_on_release, |
| .write_u64 = cgroup_write_notify_on_release, |
| .private = FILE_NOTIFY_ON_RELEASE, |
| }, |
| }; |
| |
| static struct cftype cft_release_agent = { |
| .name = "release_agent", |
| .read_seq_string = cgroup_release_agent_show, |
| .write_string = cgroup_release_agent_write, |
| .max_write_len = PATH_MAX, |
| .private = FILE_RELEASE_AGENT, |
| }; |
| |
| static int cgroup_populate_dir(struct cgroup *cgrp) |
| { |
| int err; |
| struct cgroup_subsys *ss; |
| |
| /* First clear out any existing files */ |
| cgroup_clear_directory(cgrp->dentry); |
| |
| err = cgroup_add_files(cgrp, NULL, files, ARRAY_SIZE(files)); |
| if (err < 0) |
| return err; |
| |
| if (cgrp == cgrp->top_cgroup) { |
| if ((err = cgroup_add_file(cgrp, NULL, &cft_release_agent)) < 0) |
| return err; |
| } |
| |
| for_each_subsys(cgrp->root, ss) { |
| if (ss->populate && (err = ss->populate(ss, cgrp)) < 0) |
| return err; |
| } |
| |
| return 0; |
| } |
| |
| static void init_cgroup_css(struct cgroup_subsys_state *css, |
| struct cgroup_subsys *ss, |
| struct cgroup *cgrp) |
| { |
| css->cgroup = cgrp; |
| atomic_set(&css->refcnt, 0); |
| css->flags = 0; |
| if (cgrp == dummytop) |
| set_bit(CSS_ROOT, &css->flags); |
| BUG_ON(cgrp->subsys[ss->subsys_id]); |
| cgrp->subsys[ss->subsys_id] = css; |
| } |
| |
| /* |
| * 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, |
| int mode) |
| { |
| struct cgroup *cgrp; |
| struct cgroupfs_root *root = parent->root; |
| int err = 0; |
| struct cgroup_subsys *ss; |
| struct super_block *sb = root->sb; |
| |
| cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); |
| if (!cgrp) |
| return -ENOMEM; |
| |
| /* 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); |
| |
| mutex_lock(&cgroup_mutex); |
| |
| init_cgroup_housekeeping(cgrp); |
| |
| 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); |
| |
| for_each_subsys(root, ss) { |
| struct cgroup_subsys_state *css = ss->create(ss, cgrp); |
| if (IS_ERR(css)) { |
| err = PTR_ERR(css); |
| goto err_destroy; |
| } |
| init_cgroup_css(css, ss, cgrp); |
| } |
| |
| list_add(&cgrp->sibling, &cgrp->parent->children); |
| root->number_of_cgroups++; |
| |
| err = cgroup_create_dir(cgrp, dentry, mode); |
| if (err < 0) |
| goto err_remove; |
| |
| /* The cgroup directory was pre-locked for us */ |
| BUG_ON(!mutex_is_locked(&cgrp->dentry->d_inode->i_mutex)); |
| |
| err = cgroup_populate_dir(cgrp); |
| /* If err < 0, we have a half-filled directory - oh well ;) */ |
| |
| mutex_unlock(&cgroup_mutex); |
| mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
| |
| return 0; |
| |
| err_remove: |
| |
| list_del(&cgrp->sibling); |
| root->number_of_cgroups--; |
| |
| err_destroy: |
| |
| for_each_subsys(root, ss) { |
| if (cgrp->subsys[ss->subsys_id]) |
| ss->destroy(ss, cgrp); |
| } |
| |
| mutex_unlock(&cgroup_mutex); |
| |
| /* Release the reference count that we took on the superblock */ |
| deactivate_super(sb); |
| |
| kfree(cgrp); |
| return err; |
| } |
| |
| static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, int 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); |
| } |
| |
| static int cgroup_has_css_refs(struct cgroup *cgrp) |
| { |
| /* 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 0, 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 */ |
| int i; |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| struct cgroup_subsys *ss = subsys[i]; |
| struct cgroup_subsys_state *css; |
| /* Skip subsystems not in this hierarchy */ |
| if (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 && atomic_read(&css->refcnt)) |
| return 1; |
| } |
| return 0; |
| } |
| |
| static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) |
| { |
| struct cgroup *cgrp = dentry->d_fsdata; |
| struct dentry *d; |
| struct cgroup *parent; |
| struct super_block *sb; |
| struct cgroupfs_root *root; |
| |
| /* the vfs holds both inode->i_mutex already */ |
| |
| mutex_lock(&cgroup_mutex); |
| if (atomic_read(&cgrp->count) != 0) { |
| mutex_unlock(&cgroup_mutex); |
| return -EBUSY; |
| } |
| if (!list_empty(&cgrp->children)) { |
| mutex_unlock(&cgroup_mutex); |
| return -EBUSY; |
| } |
| mutex_unlock(&cgroup_mutex); |
| |
| /* |
| * Call pre_destroy handlers of subsys. Notify subsystems |
| * that rmdir() request comes. |
| */ |
| cgroup_call_pre_destroy(cgrp); |
| |
| mutex_lock(&cgroup_mutex); |
| parent = cgrp->parent; |
| root = cgrp->root; |
| sb = root->sb; |
| |
| if (atomic_read(&cgrp->count) |
| || !list_empty(&cgrp->children) |
| || cgroup_has_css_refs(cgrp)) { |
| mutex_unlock(&cgroup_mutex); |
| return -EBUSY; |
| } |
| |
| spin_lock(&release_list_lock); |
| set_bit(CGRP_REMOVED, &cgrp->flags); |
| if (!list_empty(&cgrp->release_list)) |
| list_del(&cgrp->release_list); |
| spin_unlock(&release_list_lock); |
| /* delete my sibling from parent->children */ |
| list_del(&cgrp->sibling); |
| spin_lock(&cgrp->dentry->d_lock); |
| d = dget(cgrp->dentry); |
| spin_unlock(&d->d_lock); |
| |
| cgroup_d_remove_dir(d); |
| dput(d); |
| |
| set_bit(CGRP_RELEASABLE, &parent->flags); |
| check_for_release(parent); |
| |
| mutex_unlock(&cgroup_mutex); |
| return 0; |
| } |
| |
| 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); |
| |
| /* Create the top cgroup state for this subsystem */ |
| ss->root = &rootnode; |
| css = ss->create(ss, 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] = dummytop->subsys[ss->subsys_id]; |
| |
| need_forkexit_callback |= ss->fork || ss->exit; |
| need_mm_owner_callback |= !!ss->mm_owner_changed; |
| |
| /* 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; |
| } |
| |
| /** |
| * 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); |
| list_add(&rootnode.root_list, &roots); |
| root_count = 1; |
| init_task.cgroups = &init_css_set; |
| |
| init_css_set_link.cg = &init_css_set; |
| 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 < CSS_SET_TABLE_SIZE; i++) |
| INIT_HLIST_HEAD(&css_set_table[i]); |
| |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| struct cgroup_subsys *ss = subsys[i]; |
| |
| BUG_ON(!ss->name); |
| BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN); |
| BUG_ON(!ss->create); |
| BUG_ON(!ss->destroy); |
| 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; |
| struct hlist_head *hhead; |
| |
| 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]; |
| if (!ss->early_init) |
| cgroup_init_subsys(ss); |
| } |
| |
| /* Add init_css_set to the hash table */ |
| hhead = css_set_hash(init_css_set.subsys); |
| hlist_add_head(&init_css_set.hlist, hhead); |
| |
| err = register_filesystem(&cgroup_fs_type); |
| if (err < 0) |
| 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_root(root) { |
| struct cgroup_subsys *ss; |
| struct cgroup *cgrp; |
| int subsys_id; |
| int count = 0; |
| |
| /* Skip this hierarchy if it has no active subsystems */ |
| if (!root->actual_subsys_bits) |
| continue; |
| seq_printf(m, "%lu:", root->subsys_bits); |
| for_each_subsys(root, ss) |
| seq_printf(m, "%s%s", count++ ? "," : "", ss->name); |
| seq_putc(m, ':'); |
| get_first_subsys(&root->top_cgroup, NULL, &subsys_id); |
| cgrp = task_cgroup(tsk, subsys_id); |
| 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); |
| } |
| |
| 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"); |
| mutex_lock(&cgroup_mutex); |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| struct cgroup_subsys *ss = subsys[i]; |
| seq_printf(m, "%s\t%lu\t%d\t%d\n", |
| ss->name, ss->root->subsys_bits, |
| 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 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_fork_callbacks - run fork callbacks |
| * @child: the new task |
| * |
| * Called on a new task very soon before adding it to the |
| * tasklist. No need to take any locks since no-one can |
| * be operating on this task. |
| */ |
| void cgroup_fork_callbacks(struct task_struct *child) |
| { |
| if (need_forkexit_callback) { |
| int i; |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| struct cgroup_subsys *ss = subsys[i]; |
| if (ss->fork) |
| ss->fork(ss, child); |
| } |
| } |
| } |
| |
| #ifdef CONFIG_MM_OWNER |
| /** |
| * cgroup_mm_owner_callbacks - run callbacks when the mm->owner changes |
| * @p: the new owner |
| * |
| * Called on every change to mm->owner. mm_init_owner() does not |
| * invoke this routine, since it assigns the mm->owner the first time |
| * and does not change it. |
| * |
| * The callbacks are invoked with mmap_sem held in read mode. |
| */ |
| void cgroup_mm_owner_callbacks(struct task_struct *old, struct task_struct *new) |
| { |
| struct cgroup *oldcgrp, *newcgrp = NULL; |
| |
| if (need_mm_owner_callback) { |
| int i; |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| struct cgroup_subsys *ss = subsys[i]; |
| oldcgrp = task_cgroup(old, ss->subsys_id); |
| if (new) |
| newcgrp = task_cgroup(new, ss->subsys_id); |
| if (oldcgrp == newcgrp) |
| continue; |
| if (ss->mm_owner_changed) |
| ss->mm_owner_changed(ss, oldcgrp, newcgrp, new); |
| } |
| } |
| } |
| #endif /* CONFIG_MM_OWNER */ |
| |
| /** |
| * 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. |
| * 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) |
| { |
| if (use_task_css_set_links) { |
| write_lock(&css_set_lock); |
| if (list_empty(&child->cg_list)) |
| list_add(&child->cg_list, &child->cgroups->tasks); |
| write_unlock(&css_set_lock); |
| } |
| } |
| /** |
| * 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) |
| { |
| int i; |
| struct css_set *cg; |
| |
| if (run_callbacks && need_forkexit_callback) { |
| for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
| struct cgroup_subsys *ss = subsys[i]; |
| if (ss->exit) |
| ss->exit(ss, tsk); |
| } |
| } |
| |
| /* |
| * 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(&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; |
| task_unlock(tsk); |
| if (cg) |
| put_css_set_taskexit(cg); |
| } |
| |
| /** |
| * cgroup_clone - clone the cgroup the given subsystem is attached to |
| * @tsk: the task to be moved |
| * @subsys: the given subsystem |
| * @nodename: the name for the new cgroup |
| * |
| * Duplicate the current cgroup in the hierarchy that the given |
| * subsystem is attached to, and move this task into the new |
| * child. |
| */ |
| int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys, |
| char *nodename) |
| { |
| struct dentry *dentry; |
| int ret = 0; |
| struct cgroup *parent, *child; |
| struct inode *inode; |
| struct css_set *cg; |
| struct cgroupfs_root *root; |
| struct cgroup_subsys *ss; |
| |
| /* We shouldn't be called by an unregistered subsystem */ |
| BUG_ON(!subsys->active); |
| |
| /* First figure out what hierarchy and cgroup we're dealing |
| * with, and pin them so we can drop cgroup_mutex */ |
| mutex_lock(&cgroup_mutex); |
| again: |
| root = subsys->root; |
| if (root == &rootnode) { |
| mutex_unlock(&cgroup_mutex); |
| return 0; |
| } |
| cg = tsk->cgroups; |
| parent = task_cgroup(tsk, subsys->subsys_id); |
| |
| /* Pin the hierarchy */ |
| if (!atomic_inc_not_zero(&parent->root->sb->s_active)) { |
| /* We race with the final deactivate_super() */ |
| mutex_unlock(&cgroup_mutex); |
| return 0; |
| } |
| |
| /* Keep the cgroup alive */ |
| get_css_set(cg); |
| mutex_unlock(&cgroup_mutex); |
| |
| /* Now do the VFS work to create a cgroup */ |
| inode = parent->dentry->d_inode; |
| |
| /* Hold the parent directory mutex across this operation to |
| * stop anyone else deleting the new cgroup */ |
| mutex_lock(&inode->i_mutex); |
| dentry = lookup_one_len(nodename, parent->dentry, strlen(nodename)); |
| if (IS_ERR(dentry)) { |
| printk(KERN_INFO |
| "cgroup: Couldn't allocate dentry for %s: %ld\n", nodename, |
| PTR_ERR(dentry)); |
| ret = PTR_ERR(dentry); |
| goto out_release; |
| } |
| |
| /* Create the cgroup directory, which also creates the cgroup */ |
| ret = vfs_mkdir(inode, dentry, S_IFDIR | 0755); |
| child = __d_cgrp(dentry); |
| dput(dentry); |
| if (ret) { |
| printk(KERN_INFO |
| "Failed to create cgroup %s: %d\n", nodename, |
| ret); |
| goto out_release; |
| } |
| |
| if (!child) { |
| printk(KERN_INFO |
| "Couldn't find new cgroup %s\n", nodename); |
| ret = -ENOMEM; |
| goto out_release; |
| } |
| |
| /* The cgroup now exists. Retake cgroup_mutex and check |
| * that we're still in the same state that we thought we |
| * were. */ |
| mutex_lock(&cgroup_mutex); |
| if ((root != subsys->root) || |
| (parent != task_cgroup(tsk, subsys->subsys_id))) { |
| /* Aargh, we raced ... */ |
| mutex_unlock(&inode->i_mutex); |
| put_css_set(cg); |
| |
| deactivate_super(parent->root->sb); |
| /* The cgroup is still accessible in the VFS, but |
| * we're not going to try to rmdir() it at this |
| * point. */ |
| printk(KERN_INFO |
| "Race in cgroup_clone() - leaking cgroup %s\n", |
| nodename); |
| goto again; |
| } |
| |
| /* do any required auto-setup */ |
| for_each_subsys(root, ss) { |
| if (ss->post_clone) |
| ss->post_clone(ss, child); |
| } |
| |
| /* All seems fine. Finish by moving the task into the new cgroup */ |
| ret = cgroup_attach_task(child, tsk); |
| mutex_unlock(&cgroup_mutex); |
| |
| out_release: |
| mutex_unlock(&inode->i_mutex); |
| |
| mutex_lock(&cgroup_mutex); |
| put_css_set(cg); |
| mutex_unlock(&cgroup_mutex); |
| deactivate_super(parent->root->sb); |
| return ret; |
| } |
| |
| /** |
| * cgroup_is_descendant - see if @cgrp is a descendant of current task's cgrp |
| * @cgrp: the cgroup in question |
| * |
| * See if @cgrp is a descendant of the current 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) |
| { |
| int ret; |
| struct cgroup *target; |
| int subsys_id; |
| |
| if (cgrp == dummytop) |
| return 1; |
| |
| get_first_subsys(cgrp, NULL, &subsys_id); |
| target = task_cgroup(current, subsys_id); |
| 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; |
| 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; |
| } |
| spin_unlock(&release_list_lock); |
| if (need_schedule_work) |
| schedule_work(&release_agent_work); |
| } |
| } |
| |
| void __css_put(struct cgroup_subsys_state *css) |
| { |
| struct cgroup *cgrp = css->cgroup; |
| rcu_read_lock(); |
| if (atomic_dec_and_test(&css->refcnt) && notify_on_release(cgrp)) { |
| set_bit(CGRP_RELEASABLE, &cgrp->flags); |
| check_for_release(cgrp); |
| } |
| rcu_read_unlock(); |
| } |
| |
| /* |
| * 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); |
| 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); |
| 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); |
| spin_lock(&release_list_lock); |
| } |
| 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]; |
| |
| 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); |