diff options
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 5661 |
1 files changed, 0 insertions, 5661 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c deleted file mode 100644 index 0e0b20b8c5db..000000000000 --- a/kernel/cgroup.c +++ /dev/null @@ -1,5661 +0,0 @@ -/* - * Generic process-grouping system. - * - * Based originally on the cpuset system, extracted by Paul Menage - * Copyright (C) 2006 Google, Inc - * - * Notifications support - * Copyright (C) 2009 Nokia Corporation - * Author: Kirill A. Shutemov - * - * Copyright notices from the original cpuset code: - * -------------------------------------------------- - * Copyright (C) 2003 BULL SA. - * Copyright (C) 2004-2006 Silicon Graphics, Inc. - * - * Portions derived from Patrick Mochel's sysfs code. - * sysfs is Copyright (c) 2001-3 Patrick Mochel - * - * 2003-10-10 Written by Simon Derr. - * 2003-10-22 Updates by Stephen Hemminger. - * 2004 May-July Rework by Paul Jackson. - * --------------------------------------------------- - * - * This file is subject to the terms and conditions of the GNU General Public - * License. See the file COPYING in the main directory of the Linux - * distribution for more details. - */ - -#include <linux/cgroup.h> -#include <linux/cred.h> -#include <linux/ctype.h> -#include <linux/errno.h> -#include <linux/init_task.h> -#include <linux/kernel.h> -#include <linux/list.h> -#include <linux/mm.h> -#include <linux/mutex.h> -#include <linux/mount.h> -#include <linux/pagemap.h> -#include <linux/proc_fs.h> -#include <linux/rcupdate.h> -#include <linux/sched.h> -#include <linux/backing-dev.h> -#include <linux/seq_file.h> -#include <linux/slab.h> -#include <linux/magic.h> -#include <linux/spinlock.h> -#include <linux/string.h> -#include <linux/sort.h> -#include <linux/kmod.h> -#include <linux/module.h> -#include <linux/delayacct.h> -#include <linux/cgroupstats.h> -#include <linux/hashtable.h> -#include <linux/namei.h> -#include <linux/pid_namespace.h> -#include <linux/idr.h> -#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */ -#include <linux/eventfd.h> -#include <linux/poll.h> -#include <linux/flex_array.h> /* used in cgroup_attach_task */ -#include <linux/kthread.h> - -#include <linux/atomic.h> - -/* - * cgroup_mutex is the master lock. Any modification to cgroup or its - * hierarchy must be performed while holding it. - * - * cgroup_root_mutex nests inside cgroup_mutex and should be held to modify - * cgroupfs_root of any cgroup hierarchy - subsys list, flags, - * release_agent_path and so on. Modifying requires both cgroup_mutex and - * cgroup_root_mutex. Readers can acquire either of the two. This is to - * break the following locking order cycle. - * - * A. cgroup_mutex -> cred_guard_mutex -> s_type->i_mutex_key -> namespace_sem - * B. namespace_sem -> cgroup_mutex - * - * B happens only through cgroup_show_options() and using cgroup_root_mutex - * breaks it. - */ -#ifdef CONFIG_PROVE_RCU -DEFINE_MUTEX(cgroup_mutex); -EXPORT_SYMBOL_GPL(cgroup_mutex); /* only for task_subsys_state_check() */ -#else -static DEFINE_MUTEX(cgroup_mutex); -#endif - -static DEFINE_MUTEX(cgroup_root_mutex); - -/* - * Generate an array of cgroup subsystem pointers. At boot time, this is - * populated with the built in subsystems, and modular subsystems are - * registered after that. The mutable section of this array is protected by - * cgroup_mutex. - */ -#define SUBSYS(_x) [_x ## _subsys_id] = &_x ## _subsys, -#define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option) -static struct cgroup_subsys *cgroup_subsys[CGROUP_SUBSYS_COUNT] = { -#include <linux/cgroup_subsys.h> -}; - -/* - * 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 cgroup_dummy_root; - -/* dummy_top is a shorthand for the dummy hierarchy's top cgroup */ -static struct cgroup * const cgroup_dummy_top = &cgroup_dummy_root.top_cgroup; - -/* - * cgroupfs file entry, pointed to from leaf dentry->d_fsdata. - */ -struct cfent { - struct list_head node; - struct dentry *dentry; - struct cftype *type; - - /* file xattrs */ - struct simple_xattrs xattrs; -}; - -/* - * CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when - * cgroup_subsys->use_id != 0. - */ -#define CSS_ID_MAX (65535) -struct css_id { - /* - * The css to which this ID points. This pointer is set to valid value - * after cgroup is populated. If cgroup is removed, this will be NULL. - * This pointer is expected to be RCU-safe because destroy() - * is called after synchronize_rcu(). But for safe use, css_tryget() - * should be used for avoiding race. - */ - struct cgroup_subsys_state __rcu *css; - /* - * ID of this css. - */ - unsigned short id; - /* - * Depth in hierarchy which this ID belongs to. - */ - unsigned short depth; - /* - * ID is freed by RCU. (and lookup routine is RCU safe.) - */ - struct rcu_head rcu_head; - /* - * Hierarchy of CSS ID belongs to. - */ - unsigned short stack[0]; /* Array of Length (depth+1) */ -}; - -/* - * cgroup_event represents events which userspace want to receive. - */ -struct cgroup_event { - /* - * Cgroup which the event belongs to. - */ - struct cgroup *cgrp; - /* - * Control file which the event associated. - */ - struct cftype *cft; - /* - * eventfd to signal userspace about the event. - */ - struct eventfd_ctx *eventfd; - /* - * Each of these stored in a list by the cgroup. - */ - struct list_head list; - /* - * All fields below needed to unregister event when - * userspace closes eventfd. - */ - poll_table pt; - wait_queue_head_t *wqh; - wait_queue_t wait; - struct work_struct remove; -}; - -/* The list of hierarchy roots */ - -static LIST_HEAD(cgroup_roots); -static int cgroup_root_count; - -/* - * Hierarchy ID allocation and mapping. It follows the same exclusion - * rules as other root ops - both cgroup_mutex and cgroup_root_mutex for - * writes, either for reads. - */ -static DEFINE_IDR(cgroup_hierarchy_idr); - -static struct cgroup_name root_cgroup_name = { .name = "/" }; - -/* - * Assign a monotonically increasing serial number to cgroups. It - * guarantees cgroups with bigger numbers are newer than those with smaller - * numbers. Also, as cgroups are always appended to the parent's - * ->children list, it guarantees that sibling cgroups are always sorted in - * the ascending serial number order on the list. Protected by - * cgroup_mutex. - */ -static u64 cgroup_serial_nr_next = 1; - -/* 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 void cgroup_offline_fn(struct work_struct *work); -static int cgroup_destroy_locked(struct cgroup *cgrp); -static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys, - struct cftype cfts[], bool is_add); - -/* convenient tests for these bits */ -static inline bool cgroup_is_dead(const struct cgroup *cgrp) -{ - return test_bit(CGRP_DEAD, &cgrp->flags); -} - -/** - * cgroup_is_descendant - test ancestry - * @cgrp: the cgroup to be tested - * @ancestor: possible ancestor of @cgrp - * - * Test whether @cgrp is a descendant of @ancestor. It also returns %true - * if @cgrp == @ancestor. This function is safe to call as long as @cgrp - * and @ancestor are accessible. - */ -bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor) -{ - while (cgrp) { - if (cgrp == ancestor) - return true; - cgrp = cgrp->parent; - } - return false; -} -EXPORT_SYMBOL_GPL(cgroup_is_descendant); - -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 - iterate all loaded cgroup subsystems - * @ss: the iteration cursor - * @i: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end - * - * Should be called under cgroup_mutex. - */ -#define for_each_subsys(ss, i) \ - for ((i) = 0; (i) < CGROUP_SUBSYS_COUNT; (i)++) \ - if (({ lockdep_assert_held(&cgroup_mutex); \ - !((ss) = cgroup_subsys[i]); })) { } \ - else - -/** - * for_each_builtin_subsys - iterate all built-in cgroup subsystems - * @ss: the iteration cursor - * @i: the index of @ss, CGROUP_BUILTIN_SUBSYS_COUNT after reaching the end - * - * Bulit-in subsystems are always present and iteration itself doesn't - * require any synchronization. - */ -#define for_each_builtin_subsys(ss, i) \ - for ((i) = 0; (i) < CGROUP_BUILTIN_SUBSYS_COUNT && \ - (((ss) = cgroup_subsys[i]) || true); (i)++) - -/* iterate each subsystem attached to a hierarchy */ -#define for_each_root_subsys(root, ss) \ - list_for_each_entry((ss), &(root)->subsys_list, sibling) - -/* iterate across the active hierarchies */ -#define for_each_active_root(root) \ - list_for_each_entry((root), &cgroup_roots, root_list) - -static inline struct cgroup *__d_cgrp(struct dentry *dentry) -{ - return dentry->d_fsdata; -} - -static inline struct cfent *__d_cfe(struct dentry *dentry) -{ - return dentry->d_fsdata; -} - -static inline struct cftype *__d_cft(struct dentry *dentry) -{ - return __d_cfe(dentry)->type; -} - -/** - * 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 mutex should be later unlocked. On - * failure returns false with no lock held. - */ -static bool cgroup_lock_live_group(struct cgroup *cgrp) -{ - mutex_lock(&cgroup_mutex); - if (cgroup_is_dead(cgrp)) { - mutex_unlock(&cgroup_mutex); - return false; - } - return true; -} - -/* the list of cgroups eligible for automatic release. Protected by - * release_list_lock */ -static LIST_HEAD(release_list); -static DEFINE_RAW_SPINLOCK(release_list_lock); -static void cgroup_release_agent(struct work_struct *work); -static DECLARE_WORK(release_agent_work, cgroup_release_agent); -static void check_for_release(struct cgroup *cgrp); - -/* - * A cgroup can be associated with multiple css_sets as different tasks may - * belong to different cgroups on different hierarchies. In the other - * direction, a css_set is naturally associated with multiple cgroups. - * This M:N relationship is represented by the following link structure - * which exists for each association and allows traversing the associations - * from both sides. - */ -struct cgrp_cset_link { - /* the cgroup and css_set this link associates */ - struct cgroup *cgrp; - struct css_set *cset; - - /* list of cgrp_cset_links anchored at cgrp->cset_links */ - struct list_head cset_link; - - /* list of cgrp_cset_links anchored at css_set->cgrp_links */ - struct list_head cgrp_link; -}; - -/* The default css_set - used by init and its children prior to any - * hierarchies being mounted. It contains a pointer to the root state - * for each subsystem. Also used to anchor the list of css_sets. Not - * reference-counted, to improve performance when child cgroups - * haven't been created. - */ - -static struct css_set init_css_set; -static struct cgrp_cset_link init_cgrp_cset_link; - -static int cgroup_init_idr(struct cgroup_subsys *ss, - struct cgroup_subsys_state *css); - -/* css_set_lock protects the list of css_set objects, and the - * chain of tasks off each css_set. Nests outside task->alloc_lock - * due to cgroup_iter_start() */ -static DEFINE_RWLOCK(css_set_lock); -static int css_set_count; - -/* - * hash table for cgroup groups. This improves the performance to find - * an existing css_set. This hash doesn't (currently) take into - * account cgroups in empty hierarchies. - */ -#define CSS_SET_HASH_BITS 7 -static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS); - -static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) -{ - unsigned long key = 0UL; - struct cgroup_subsys *ss; - int i; - - for_each_subsys(ss, i) - key += (unsigned long)css[i]; - key = (key >> 16) ^ key; - - return key; -} - -/* We don't maintain the lists running through each css_set to its - * task until after the first call to cgroup_iter_start(). This - * reduces the fork()/exit() overhead for people who have cgroups - * compiled into their kernel but not actually in use */ -static int use_task_css_set_links __read_mostly; - -static void __put_css_set(struct css_set *cset, int taskexit) -{ - struct cgrp_cset_link *link, *tmp_link; - - /* - * Ensure that the refcount doesn't hit zero while any readers - * can see it. Similar to atomic_dec_and_lock(), but for an - * rwlock - */ - if (atomic_add_unless(&cset->refcount, -1, 1)) - return; - write_lock(&css_set_lock); - if (!atomic_dec_and_test(&cset->refcount)) { - write_unlock(&css_set_lock); - return; - } - - /* This css_set is dead. unlink it and release cgroup refcounts */ - hash_del(&cset->hlist); - css_set_count--; - - list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) { - struct cgroup *cgrp = link->cgrp; - - list_del(&link->cset_link); - list_del(&link->cgrp_link); - - /* @cgrp can't go away while we're holding css_set_lock */ - if (list_empty(&cgrp->cset_links) && notify_on_release(cgrp)) { - if (taskexit) - set_bit(CGRP_RELEASABLE, &cgrp->flags); - check_for_release(cgrp); - } - - kfree(link); - } - - write_unlock(&css_set_lock); - kfree_rcu(cset, rcu_head); -} - -/* - * refcounted get/put for css_set objects - */ -static inline void get_css_set(struct css_set *cset) -{ - atomic_inc(&cset->refcount); -} - -static inline void put_css_set(struct css_set *cset) -{ - __put_css_set(cset, 0); -} - -static inline void put_css_set_taskexit(struct css_set *cset) -{ - __put_css_set(cset, 1); -} - -/** - * compare_css_sets - helper function for find_existing_css_set(). - * @cset: candidate css_set being tested - * @old_cset: existing css_set for a task - * @new_cgrp: cgroup that's being entered by the task - * @template: desired set of css pointers in css_set (pre-calculated) - * - * Returns true if "cg" matches "old_cg" except for the hierarchy - * which "new_cgrp" belongs to, for which it should match "new_cgrp". - */ -static bool compare_css_sets(struct css_set *cset, - struct css_set *old_cset, - struct cgroup *new_cgrp, - struct cgroup_subsys_state *template[]) -{ - struct list_head *l1, *l2; - - if (memcmp(template, cset->subsys, sizeof(cset->subsys))) { - /* Not all subsystems matched */ - return false; - } - - /* - * Compare cgroup pointers in order to distinguish between - * different cgroups in heirarchies with no subsystems. We - * could get by with just this check alone (and skip the - * memcmp above) but on most setups the memcmp check will - * avoid the need for this more expensive check on almost all - * candidates. - */ - - l1 = &cset->cgrp_links; - l2 = &old_cset->cgrp_links; - while (1) { - struct cgrp_cset_link *link1, *link2; - struct cgroup *cgrp1, *cgrp2; - - l1 = l1->next; - l2 = l2->next; - /* See if we reached the end - both lists are equal length. */ - if (l1 == &cset->cgrp_links) { - BUG_ON(l2 != &old_cset->cgrp_links); - break; - } else { - BUG_ON(l2 == &old_cset->cgrp_links); - } - /* Locate the cgroups associated with these links. */ - link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link); - link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link); - cgrp1 = link1->cgrp; - cgrp2 = link2->cgrp; - /* Hierarchies should be linked in the same order. */ - BUG_ON(cgrp1->root != cgrp2->root); - - /* - * If this hierarchy is the hierarchy of the cgroup - * that's changing, then we need to check that this - * css_set points to the new cgroup; if it's any other - * hierarchy, then this css_set should point to the - * same cgroup as the old css_set. - */ - if (cgrp1->root == new_cgrp->root) { - if (cgrp1 != new_cgrp) - return false; - } else { - if (cgrp1 != cgrp2) - return false; - } - } - return true; -} - -/** - * find_existing_css_set - init css array and find the matching css_set - * @old_cset: the css_set that we're using before the cgroup transition - * @cgrp: the cgroup that we're moving into - * @template: out param for the new set of csses, should be clear on entry - */ -static struct css_set *find_existing_css_set(struct css_set *old_cset, - struct cgroup *cgrp, - struct cgroup_subsys_state *template[]) -{ - struct cgroupfs_root *root = cgrp->root; - struct cgroup_subsys *ss; - struct css_set *cset; - unsigned long key; - int i; - - /* - * Build the set of subsystem state objects that we want to see in the - * new css_set. while subsystems can change globally, the entries here - * won't change, so no need for locking. - */ - for_each_subsys(ss, i) { - if (root->subsys_mask & (1UL << i)) { - /* 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] = old_cset->subsys[i]; - } - } - - key = css_set_hash(template); - hash_for_each_possible(css_set_table, cset, hlist, key) { - if (!compare_css_sets(cset, old_cset, cgrp, template)) - continue; - - /* This css_set matches what we need */ - return cset; - } - - /* No existing cgroup group matched */ - return NULL; -} - -static void free_cgrp_cset_links(struct list_head *links_to_free) -{ - struct cgrp_cset_link *link, *tmp_link; - - list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) { - list_del(&link->cset_link); - kfree(link); - } -} - -/** - * allocate_cgrp_cset_links - allocate cgrp_cset_links - * @count: the number of links to allocate - * @tmp_links: list_head the allocated links are put on - * - * Allocate @count cgrp_cset_link structures and chain them on @tmp_links - * through ->cset_link. Returns 0 on success or -errno. - */ -static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links) -{ - struct cgrp_cset_link *link; - int i; - - INIT_LIST_HEAD(tmp_links); - - for (i = 0; i < count; i++) { - link = kzalloc(sizeof(*link), GFP_KERNEL); - if (!link) { - free_cgrp_cset_links(tmp_links); - return -ENOMEM; - } - list_add(&link->cset_link, tmp_links); - } - return 0; -} - -/** - * link_css_set - a helper function to link a css_set to a cgroup - * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links() - * @cset: the css_set to be linked - * @cgrp: the destination cgroup - */ -static void link_css_set(struct list_head *tmp_links, struct css_set *cset, - struct cgroup *cgrp) -{ - struct cgrp_cset_link *link; - - BUG_ON(list_empty(tmp_links)); - link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link); - link->cset = cset; - link->cgrp = cgrp; - list_move(&link->cset_link, &cgrp->cset_links); - /* - * Always add links to the tail of the list so that the list - * is sorted by order of hierarchy creation - */ - list_add_tail(&link->cgrp_link, &cset->cgrp_links); -} - -/** - * find_css_set - return a new css_set with one cgroup updated - * @old_cset: the baseline css_set - * @cgrp: the cgroup to be updated - * - * Return a new css_set that's equivalent to @old_cset, but with @cgrp - * substituted into the appropriate hierarchy. - */ -static struct css_set *find_css_set(struct css_set *old_cset, - struct cgroup *cgrp) -{ - struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { }; - struct css_set *cset; - struct list_head tmp_links; - struct cgrp_cset_link *link; - unsigned long key; - - lockdep_assert_held(&cgroup_mutex); - - /* First see if we already have a cgroup group that matches - * the desired set */ - read_lock(&css_set_lock); - cset = find_existing_css_set(old_cset, cgrp, template); - if (cset) - get_css_set(cset); - read_unlock(&css_set_lock); - - if (cset) - return cset; - - cset = kzalloc(sizeof(*cset), GFP_KERNEL); - if (!cset) - return NULL; - - /* Allocate all the cgrp_cset_link objects that we'll need */ - if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) { - kfree(cset); - return NULL; - } - - atomic_set(&cset->refcount, 1); - INIT_LIST_HEAD(&cset->cgrp_links); - INIT_LIST_HEAD(&cset->tasks); - INIT_HLIST_NODE(&cset->hlist); - - /* Copy the set of subsystem state objects generated in - * find_existing_css_set() */ - memcpy(cset->subsys, template, sizeof(cset->subsys)); - - write_lock(&css_set_lock); - /* Add reference counts and links from the new css_set. */ - list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) { - struct cgroup *c = link->cgrp; - - if (c->root == cgrp->root) - c = cgrp; - link_css_set(&tmp_links, cset, c); - } - - BUG_ON(!list_empty(&tmp_links)); - - css_set_count++; - - /* Add this cgroup group to the hash table */ - key = css_set_hash(cset->subsys); - hash_add(css_set_table, &cset->hlist, key); - - write_unlock(&css_set_lock); - - return cset; -} - -/* - * Return the cgroup for "task" from the given hierarchy. Must be - * called with cgroup_mutex held. - */ -static struct cgroup *task_cgroup_from_root(struct task_struct *task, - struct cgroupfs_root *root) -{ - struct css_set *cset; - struct cgroup *res = NULL; - - BUG_ON(!mutex_is_locked(&cgroup_mutex)); - read_lock(&css_set_lock); - /* - * No need to lock the task - since we hold cgroup_mutex the - * task can't change groups, so the only thing that can happen - * is that it exits and its css is set back to init_css_set. - */ - cset = task_css_set(task); - if (cset == &init_css_set) { - res = &root->top_cgroup; - } else { - struct cgrp_cset_link *link; - - list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { - struct cgroup *c = link->cgrp; - - if (c->root == root) { - res = c; - break; - } - } - } - read_unlock(&css_set_lock); - BUG_ON(!res); - return res; -} - -/* - * There is one global cgroup mutex. We also require taking - * task_lock() when dereferencing a task's cgroup subsys pointers. - * See "The task_lock() exception", at the end of this comment. - * - * A task must hold cgroup_mutex to modify cgroups. - * - * Any task can increment and decrement the count field without lock. - * So in general, code holding cgroup_mutex can't rely on the count - * field not changing. However, if the count goes to zero, then only - * cgroup_attach_task() can increment it again. Because a count of zero - * means that no tasks are currently attached, therefore there is no - * way a task attached to that cgroup can fork (the other way to - * increment the count). So code holding cgroup_mutex can safely - * assume that if the count is zero, it will stay zero. Similarly, if - * a task holds cgroup_mutex on a cgroup with zero count, it - * knows that the cgroup won't be removed, as cgroup_rmdir() - * needs that mutex. - * - * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't - * (usually) take cgroup_mutex. These are the two most performance - * critical pieces of code here. The exception occurs on cgroup_exit(), - * when a task in a notify_on_release cgroup exits. Then cgroup_mutex - * is taken, and if the cgroup count is zero, a usermode call made - * to the release agent with the name of the cgroup (path relative to - * the root of cgroup file system) as the argument. - * - * A cgroup can only be deleted if both its 'count' of using tasks - * is zero, and its list of 'children' cgroups is empty. Since all - * tasks in the system use _some_ cgroup, and since there is always at - * least one task in the system (init, pid == 1), therefore, top_cgroup - * always has either children cgroups and/or using tasks. So we don't - * need a special hack to ensure that top_cgroup cannot be deleted. - * - * The task_lock() exception - * - * The need for this exception arises from the action of - * cgroup_attach_task(), which overwrites one task's cgroup pointer with - * another. It does so using cgroup_mutex, however there are - * several performance critical places that need to reference - * task->cgroup without the expense of grabbing a system global - * mutex. Therefore except as noted below, when dereferencing or, as - * in cgroup_attach_task(), modifying a task's cgroup pointer we use - * task_lock(), which acts on a spinlock (task->alloc_lock) already in - * the task_struct routinely used for such matters. - * - * P.S. One more locking exception. RCU is used to guard the - * update of a tasks cgroup pointer by cgroup_attach_task() - */ - -/* - * A couple of forward declarations required, due to cyclic reference loop: - * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir -> - * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations - * -> cgroup_mkdir. - */ - -static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode); -static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry); -static int cgroup_populate_dir(struct cgroup *cgrp, bool base_files, - unsigned long subsys_mask); -static const struct inode_operations cgroup_dir_inode_operations; -static const struct file_operations proc_cgroupstats_operations; - -static struct backing_dev_info cgroup_backing_dev_info = { - .name = "cgroup", - .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, -}; - -static int alloc_css_id(struct cgroup_subsys *ss, - struct cgroup *parent, struct cgroup *child); - -static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb) -{ - struct inode *inode = new_inode(sb); - - if (inode) { - inode->i_ino = get_next_ino(); - inode->i_mode = mode; - inode->i_uid = current_fsuid(); - inode->i_gid = current_fsgid(); - inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; - inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info; - } - return inode; -} - -static struct cgroup_name *cgroup_alloc_name(struct dentry *dentry) -{ - struct cgroup_name *name; - - name = kmalloc(sizeof(*name) + dentry->d_name.len + 1, GFP_KERNEL); - if (!name) - return NULL; - strcpy(name->name, dentry->d_name.name); - return name; -} - -static void cgroup_free_fn(struct work_struct *work) -{ - struct cgroup *cgrp = container_of(work, struct cgroup, destroy_work); - struct cgroup_subsys *ss; - - mutex_lock(&cgroup_mutex); - /* - * Release the subsystem state objects. - */ - for_each_root_subsys(cgrp->root, ss) - ss->css_free(cgrp); - - cgrp->root->number_of_cgroups--; - mutex_unlock(&cgroup_mutex); - - /* - * We get a ref to the parent's dentry, and put the ref when - * this cgroup is being freed, so it's guaranteed that the - * parent won't be destroyed before its children. - */ - dput(cgrp->parent->dentry); - - ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id); - - /* - * Drop the active superblock reference that we took when we - * created the cgroup. This will free cgrp->root, if we are - * holding the last reference to @sb. - */ - deactivate_super(cgrp->root->sb); - - /* - * if we're getting rid of the cgroup, refcount should ensure - * that there are no pidlists left. - */ - BUG_ON(!list_empty(&cgrp->pidlists)); - - simple_xattrs_free(&cgrp->xattrs); - - kfree(rcu_dereference_raw(cgrp->name)); - kfree(cgrp); -} - -static void cgroup_free_rcu(struct rcu_head *head) -{ - struct cgroup *cgrp = container_of(head, struct cgroup, rcu_head); - - INIT_WORK(&cgrp->destroy_work, cgroup_free_fn); - schedule_work(&cgrp->destroy_work); -} - -static void cgroup_diput(struct dentry *dentry, struct inode *inode) -{ - /* is dentry a directory ? if so, kfree() associated cgroup */ - if (S_ISDIR(inode->i_mode)) { - struct cgroup *cgrp = dentry->d_fsdata; - - BUG_ON(!(cgroup_is_dead(cgrp))); - call_rcu(&cgrp->rcu_head, cgroup_free_rcu); - } else { - struct cfent *cfe = __d_cfe(dentry); - struct cgroup *cgrp = dentry->d_parent->d_fsdata; - - WARN_ONCE(!list_empty(&cfe->node) && - cgrp != &cgrp->root->top_cgroup, - "cfe still linked for %s\n", cfe->type->name); - simple_xattrs_free(&cfe->xattrs); - kfree(cfe); - } - iput(inode); -} - -static int cgroup_delete(const struct dentry *d) -{ - return 1; -} - -static void remove_dir(struct dentry *d) -{ - struct dentry *parent = dget(d->d_parent); - - d_delete(d); - simple_rmdir(parent->d_inode, d); - dput(parent); -} - -static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) -{ - struct cfent *cfe; - - lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex); - lockdep_assert_held(&cgroup_mutex); - - /* - * If we're doing cleanup due to failure of cgroup_create(), - * the corresponding @cfe may not exist. - */ - list_for_each_entry(cfe, &cgrp->files, node) { - struct dentry *d = cfe->dentry; - - if (cft && cfe->type != cft) - continue; - - dget(d); - d_delete(d); - simple_unlink(cgrp->dentry->d_inode, d); - list_del_init(&cfe->node); - dput(d); - - break; - } -} - -/** - * cgroup_clear_directory - selective removal of base and subsystem files - * @dir: directory containing the files - * @base_files: true if the base files should be removed - * @subsys_mask: mask of the subsystem ids whose files should be removed - */ -static void cgroup_clear_directory(struct dentry *dir, bool base_files, - unsigned long subsys_mask) -{ - struct cgroup *cgrp = __d_cgrp(dir); - struct cgroup_subsys *ss; - - for_each_root_subsys(cgrp->root, ss) { - struct cftype_set *set; - if (!test_bit(ss->subsys_id, &subsys_mask)) - continue; - list_for_each_entry(set, &ss->cftsets, node) - cgroup_addrm_files(cgrp, NULL, set->cfts, false); - } - if (base_files) { - while (!list_empty(&cgrp->files)) - cgroup_rm_file(cgrp, NULL); - } -} - -/* - * NOTE : the dentry must have been dget()'ed - */ -static void cgroup_d_remove_dir(struct dentry *dentry) -{ - struct dentry *parent; - struct cgroupfs_root *root = dentry->d_sb->s_fs_info; - - cgroup_clear_directory(dentry, true, root->subsys_mask); - - parent = dentry->d_parent; - spin_lock(&parent->d_lock); - spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); - list_del_init(&dentry->d_u.d_child); - spin_unlock(&dentry->d_lock); - spin_unlock(&parent->d_lock); - remove_dir(dentry); -} - -/* - * Call with cgroup_mutex held. Drops reference counts on modules, including - * any duplicate ones that parse_cgroupfs_options took. If this function - * returns an error, no reference counts are touched. - */ -static int rebind_subsystems(struct cgroupfs_root *root, - unsigned long added_mask, unsigned removed_mask) -{ - struct cgroup *cgrp = &root->top_cgroup; - struct cgroup_subsys *ss; - int i; - - BUG_ON(!mutex_is_locked(&cgroup_mutex)); - BUG_ON(!mutex_is_locked(&cgroup_root_mutex)); - - /* Check that any added subsystems are currently free */ - for_each_subsys(ss, i) { - unsigned long bit = 1UL << i; - - if (!(bit & added_mask)) - continue; - - if (ss->root != &cgroup_dummy_root) { - /* 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_each_subsys(ss, i) { - unsigned long bit = 1UL << i; - - if (bit & added_mask) { - /* We're binding this subsystem to this hierarchy */ - BUG_ON(cgrp->subsys[i]); - BUG_ON(!cgroup_dummy_top->subsys[i]); - BUG_ON(cgroup_dummy_top->subsys[i]->cgroup != cgroup_dummy_top); - - cgrp->subsys[i] = cgroup_dummy_top->subsys[i]; - cgrp->subsys[i]->cgroup = cgrp; - list_move(&ss->sibling, &root->subsys_list); - ss->root = root; - if (ss->bind) - ss->bind(cgrp); - - /* refcount was already taken, and we're keeping it */ - root->subsys_mask |= bit; - } else if (bit & removed_mask) { - /* We're removing this subsystem */ - BUG_ON(cgrp->subsys[i] != cgroup_dummy_top->subsys[i]); - BUG_ON(cgrp->subsys[i]->cgroup != cgrp); - - if (ss->bind) - ss->bind(cgroup_dummy_top); - cgroup_dummy_top->subsys[i]->cgroup = cgroup_dummy_top; - cgrp->subsys[i] = NULL; - cgroup_subsys[i]->root = &cgroup_dummy_root; - list_move(&ss->sibling, &cgroup_dummy_root.subsys_list); - - /* subsystem is now free - drop reference on module */ - module_put(ss->module); - root->subsys_mask &= ~bit; - } else if (bit & root->subsys_mask) { - /* Subsystem state should already exist */ - BUG_ON(!cgrp->subsys[i]); - /* - * a refcount was taken, but we already had one, so - * drop the extra reference. - */ - module_put(ss->module); -#ifdef CONFIG_MODULE_UNLOAD - BUG_ON(ss->module && !module_refcount(ss->module)); -#endif - } else { - /* Subsystem state shouldn't exist */ - BUG_ON(cgrp->subsys[i]); - } - } - - /* - * Mark @root has finished binding subsystems. @root->subsys_mask - * now matches the bound subsystems. - */ - root->flags |= CGRP_ROOT_SUBSYS_BOUND; - - return 0; -} - -static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry) -{ - struct cgroupfs_root *root = dentry->d_sb->s_fs_info; - struct cgroup_subsys *ss; - - mutex_lock(&cgroup_root_mutex); - for_each_root_subsys(root, ss) - seq_printf(seq, ",%s", ss->name); - if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) - seq_puts(seq, ",sane_behavior"); - if (root->flags & CGRP_ROOT_NOPREFIX) - seq_puts(seq, ",noprefix"); - if (root->flags & CGRP_ROOT_XATTR) - seq_puts(seq, ",xattr"); - if (strlen(root->release_agent_path)) - seq_printf(seq, ",release_agent=%s", root->release_agent_path); - if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->top_cgroup.flags)) - seq_puts(seq, ",clone_children"); - if (strlen(root->name)) - seq_printf(seq, ",name=%s", root->name); - mutex_unlock(&cgroup_root_mutex); - return 0; -} - -struct cgroup_sb_opts { - unsigned long subsys_mask; - unsigned long flags; - char *release_agent; - bool cpuset_clone_children; - char *name; - /* User explicitly requested empty subsystem */ - bool none; - - struct cgroupfs_root *new_root; - -}; - -/* - * Convert a hierarchy specifier into a bitmask of subsystems and - * flags. Call with cgroup_mutex held to protect the cgroup_subsys[] - * array. This function takes refcounts on subsystems to be used, unless it - * returns error, in which case no refcounts are taken. - */ -static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) -{ - char *token, *o = data; - bool all_ss = false, one_ss = false; - unsigned long mask = (unsigned long)-1; - bool module_pin_failed = false; - struct cgroup_subsys *ss; - int i; - - BUG_ON(!mutex_is_locked(&cgroup_mutex)); - -#ifdef CONFIG_CPUSETS - mask = ~(1UL << cpuset_subsys_id); -#endif - - memset(opts, 0, sizeof(*opts)); - - while ((token = strsep(&o, ",")) != NULL) { - if (!*token) - return -EINVAL; - if (!strcmp(token, "none")) { - /* Explicitly have no subsystems */ - opts->none = true; - continue; - } - if (!strcmp(token, "all")) { - /* Mutually exclusive option 'all' + subsystem name */ - if (one_ss) - return -EINVAL; - all_ss = true; - continue; - } - if (!strcmp(token, "__DEVEL__sane_behavior")) { - opts->flags |= CGRP_ROOT_SANE_BEHAVIOR; - continue; - } - if (!strcmp(token, "noprefix")) { - opts->flags |= CGRP_ROOT_NOPREFIX; - continue; - } - if (!strcmp(token, "clone_children")) { - opts->cpuset_clone_children = true; - continue; - } - if (!strcmp(token, "xattr")) { - opts->flags |= CGRP_ROOT_XATTR; - continue; - } - if (!strncmp(token, "release_agent=", 14)) { - /* Specifying two release agents is forbidden */ - if (opts->release_agent) - return -EINVAL; - opts->release_agent = - kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL); - if (!opts->release_agent) - return -ENOMEM; - continue; - } - if (!strncmp(token, "name=", 5)) { - const char *name = token + 5; - /* Can't specify an empty name */ - if (!strlen(name)) - return -EINVAL; - /* Must match [\w.-]+ */ - for (i = 0; i < strlen(name); i++) { - char c = name[i]; - if (isalnum(c)) - continue; - if ((c == '.') || (c == '-') || (c == '_')) - continue; - return -EINVAL; - } - /* Specifying two names is forbidden */ - if (opts->name) - return -EINVAL; - opts->name = kstrndup(name, - MAX_CGROUP_ROOT_NAMELEN - 1, - GFP_KERNEL); - if (!opts->name) - return -ENOMEM; - - continue; - } - - for_each_subsys(ss, i) { - if (strcmp(token, ss->name)) - continue; - if (ss->disabled) - continue; - - /* Mutually exclusive option 'all' + subsystem name */ - if (all_ss) - return -EINVAL; - set_bit(i, &opts->subsys_mask); - one_ss = true; - - break; - } - if (i == CGROUP_SUBSYS_COUNT) - return -ENOENT; - } - - /* - * If the 'all' option was specified select all the subsystems, - * otherwise if 'none', 'name=' and a subsystem name options - * were not specified, let's default to 'all' - */ - if (all_ss || (!one_ss && !opts->none && !opts->name)) - for_each_subsys(ss, i) - if (!ss->disabled) - set_bit(i, &opts->subsys_mask); - - /* Consistency checks */ - - if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) { - pr_warning("cgroup: sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n"); - - if (opts->flags & CGRP_ROOT_NOPREFIX) { - pr_err("cgroup: sane_behavior: noprefix is not allowed\n"); - return -EINVAL; - } - - if (opts->cpuset_clone_children) { - pr_err("cgroup: sane_behavior: clone_children is not allowed\n"); - return -EINVAL; - } - } - - /* - * Option noprefix was introduced just for backward compatibility - * with the old cpuset, so we allow noprefix only if mounting just - * the cpuset subsystem. - */ - if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask)) - return -EINVAL; - - - /* Can't specify "none" and some subsystems */ - if (opts->subsys_mask && opts->none) - return -EINVAL; - - /* - * We either have to specify by name or by subsystems. (So all - * empty hierarchies must have a name). - */ - if (!opts->subsys_mask && !opts->name) - return -EINVAL; - - /* - * Grab references on all the modules we'll need, so the subsystems - * don't dance around before rebind_subsystems attaches them. This may - * take duplicate reference counts on a subsystem that's already used, - * but rebind_subsystems handles this case. - */ - for_each_subsys(ss, i) { - if (!(opts->subsys_mask & (1UL << i))) - continue; - if (!try_module_get(cgroup_subsys[i]->module)) { - module_pin_failed = true; - break; - } - } - if (module_pin_failed) { - /* - * oops, one of the modules was going away. this means that we - * raced with a module_delete call, and to the user this is - * essentially a "subsystem doesn't exist" case. - */ - for (i--; i >= 0; i--) { - /* drop refcounts only on the ones we took */ - unsigned long bit = 1UL << i; - - if (!(bit & opts->subsys_mask)) - continue; - module_put(cgroup_subsys[i]->module); - } - return -ENOENT; - } - - return 0; -} - -static void drop_parsed_module_refcounts(unsigned long subsys_mask) -{ - struct cgroup_subsys *ss; - int i; - - mutex_lock(&cgroup_mutex); - for_each_subsys(ss, i) - if (subsys_mask & (1UL << i)) - module_put(cgroup_subsys[i]->module); - mutex_unlock(&cgroup_mutex); -} - -static int cgroup_remount(struct super_block *sb, int *flags, char *data) -{ - int ret = 0; - struct cgroupfs_root *root = sb->s_fs_info; - struct cgroup *cgrp = &root->top_cgroup; - struct cgroup_sb_opts opts; - unsigned long added_mask, removed_mask; - - if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) { - pr_err("cgroup: sane_behavior: remount is not allowed\n"); - return -EINVAL; - } - - mutex_lock(&cgrp->dentry->d_inode->i_mutex); - mutex_lock(&cgroup_mutex); - mutex_lock(&cgroup_root_mutex); - - /* See what subsystems are wanted */ - ret = parse_cgroupfs_options(data, &opts); - if (ret) - goto out_unlock; - - if (opts.subsys_mask != root->subsys_mask || opts.release_agent) - pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n", - task_tgid_nr(current), current->comm); - - added_mask = opts.subsys_mask & ~root->subsys_mask; - removed_mask = root->subsys_mask & ~opts.subsys_mask; - - /* Don't allow flags or name to change at remount */ - if (((opts.flags ^ root->flags) & CGRP_ROOT_OPTION_MASK) || - (opts.name && strcmp(opts.name, root->name))) { - pr_err("cgroup: option or name mismatch, new: 0x%lx \"%s\", old: 0x%lx \"%s\"\n", - opts.flags & CGRP_ROOT_OPTION_MASK, opts.name ?: "", - root->flags & CGRP_ROOT_OPTION_MASK, root->name); - ret = -EINVAL; - goto out_unlock; - } - - /* - * Clear out the files of subsystems that should be removed, do - * this before rebind_subsystems, since rebind_subsystems may - * change this hierarchy's subsys_list. - */ - cgroup_clear_directory(cgrp->dentry, false, removed_mask); - - ret = rebind_subsystems(root, added_mask, removed_mask); - if (ret) { - /* rebind_subsystems failed, re-populate the removed files */ - cgroup_populate_dir(cgrp, false, removed_mask); - goto out_unlock; - } - - /* re-populate subsystem files */ - cgroup_populate_dir(cgrp, false, added_mask); - - if (opts.release_agent) - strcpy(root->release_agent_path, opts.release_agent); - out_unlock: - kfree(opts.release_agent); - kfree(opts.name); - mutex_unlock(&cgroup_root_mutex); - mutex_unlock(&cgroup_mutex); - mutex_unlock(&cgrp->dentry->d_inode->i_mutex); - if (ret) - drop_parsed_module_refcounts(opts.subsys_mask); - return ret; -} - -static const struct super_operations cgroup_ops = { - .statfs = simple_statfs, - .drop_inode = generic_delete_inode, - .show_options = cgroup_show_options, - .remount_fs = cgroup_remount, -}; - -static void init_cgroup_housekeeping(struct cgroup *cgrp) -{ - INIT_LIST_HEAD(&cgrp->sibling); - INIT_LIST_HEAD(&cgrp->children); - INIT_LIST_HEAD(&cgrp->files); - INIT_LIST_HEAD(&cgrp->cset_links); - INIT_LIST_HEAD(&cgrp->release_list); - INIT_LIST_HEAD(&cgrp->pidlists); - mutex_init(&cgrp->pidlist_mutex); - INIT_LIST_HEAD(&cgrp->event_list); - spin_lock_init(&cgrp->event_list_lock); - simple_xattrs_init(&cgrp->xattrs); -} - -static void init_cgroup_root(struct cgroupfs_root *root) -{ - struct cgroup *cgrp = &root->top_cgroup; - - INIT_LIST_HEAD(&root->subsys_list); - INIT_LIST_HEAD(&root->root_list); - root->number_of_cgroups = 1; - cgrp->root = root; - RCU_INIT_POINTER(cgrp->name, &root_cgroup_name); - init_cgroup_housekeeping(cgrp); -} - -static int cgroup_init_root_id(struct cgroupfs_root *root, int start, int end) -{ - int id; - - lockdep_assert_held(&cgroup_mutex); - lockdep_assert_held(&cgroup_root_mutex); - - id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, start, end, - GFP_KERNEL); - if (id < 0) - return id; - - root->hierarchy_id = id; - return 0; -} - -static void cgroup_exit_root_id(struct cgroupfs_root *root) -{ - lockdep_assert_held(&cgroup_mutex); - lockdep_assert_held(&cgroup_root_mutex); - - if (root->hierarchy_id) { - idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id); - root->hierarchy_id = 0; - } -} - -static int cgroup_test_super(struct super_block *sb, void *data) -{ - struct cgroup_sb_opts *opts = data; - struct cgroupfs_root *root = sb->s_fs_info; - - /* If we asked for a name then it must match */ - if (opts->name && strcmp(opts->name, root->name)) - return 0; - - /* - * If we asked for subsystems (or explicitly for no - * subsystems) then they must match - */ - if ((opts->subsys_mask || opts->none) - && (opts->subsys_mask != root->subsys_mask)) - return 0; - - return 1; -} - -static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) -{ - struct cgroupfs_root *root; - - if (!opts->subsys_mask && !opts->none) - return NULL; - - root = kzalloc(sizeof(*root), GFP_KERNEL); - if (!root) - return ERR_PTR(-ENOMEM); - - init_cgroup_root(root); - - /* - * We need to set @root->subsys_mask now so that @root can be - * matched by cgroup_test_super() before it finishes - * initialization; otherwise, competing mounts with the same - * options may try to bind the same subsystems instead of waiting - * for the first one leading to unexpected mount errors. - * SUBSYS_BOUND will be set once actual binding is complete. - */ - root->subsys_mask = opts->subsys_mask; - root->flags = opts->flags; - ida_init(&root->cgroup_ida); - if (opts->release_agent) - strcpy(root->release_agent_path, opts->release_agent); - if (opts->name) - strcpy(root->name, opts->name); - if (opts->cpuset_clone_children) - set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->top_cgroup.flags); - return root; -} - -static void cgroup_free_root(struct cgroupfs_root *root) -{ - if (root) { - /* hierarhcy ID shoulid already have been released */ - WARN_ON_ONCE(root->hierarchy_id); - - ida_destroy(&root->cgroup_ida); - kfree(root); - } -} - -static int cgroup_set_super(struct super_block *sb, void *data) -{ - int ret; - struct cgroup_sb_opts *opts = data; - - /* If we don't have a new root, we can't set up a new sb */ - if (!opts->new_root) - return -EINVAL; - - BUG_ON(!opts->subsys_mask && !opts->none); - - ret = set_anon_super(sb, NULL); - if (ret) - return ret; - - sb->s_fs_info = opts->new_root; - opts->new_root->sb = sb; - - sb->s_blocksize = PAGE_CACHE_SIZE; - sb->s_blocksize_bits = PAGE_CACHE_SHIFT; - sb->s_magic = CGROUP_SUPER_MAGIC; - sb->s_op = &cgroup_ops; - - return 0; -} - -static int cgroup_get_rootdir(struct super_block *sb) -{ - static const struct dentry_operations cgroup_dops = { - .d_iput = cgroup_diput, - .d_delete = cgroup_delete, - }; - - struct inode *inode = - cgroup_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR, sb); - - if (!inode) - return -ENOMEM; - - inode->i_fop = &simple_dir_operations; - inode->i_op = &cgroup_dir_inode_operations; - /* directories start off with i_nlink == 2 (for "." entry) */ - inc_nlink(inode); - sb->s_root = d_make_root(inode); - if (!sb->s_root) - return -ENOMEM; - /* for everything else we want ->d_op set */ - sb->s_d_op = &cgroup_dops; - return 0; -} - -static struct dentry *cgroup_mount(struct file_system_type *fs_type, - int flags, const char *unused_dev_name, - void *data) -{ - struct cgroup_sb_opts opts; - struct cgroupfs_root *root; - int ret = 0; - struct super_block *sb; - struct cgroupfs_root *new_root; - struct inode *inode; - - /* First find the desired set of subsystems */ - mutex_lock(&cgroup_mutex); - ret = parse_cgroupfs_options(data, &opts); - mutex_unlock(&cgroup_mutex); - if (ret) - goto out_err; - - /* - * Allocate a new cgroup root. We may not need it if we're - * reusing an existing hierarchy. - */ - new_root = cgroup_root_from_opts(&opts); - if (IS_ERR(new_root)) { - ret = PTR_ERR(new_root); - goto drop_modules; - } - opts.new_root = new_root; - - /* Locate an existing or new sb for this hierarchy */ - sb = sget(fs_type, cgroup_test_super, cgroup_set_super, 0, &opts); - if (IS_ERR(sb)) { - ret = PTR_ERR(sb); - cgroup_free_root(opts.new_root); - goto drop_modules; - } - - root = sb->s_fs_info; - BUG_ON(!root); - if (root == opts.new_root) { - /* We used the new root structure, so this is a new hierarchy */ - struct list_head tmp_links; - struct cgroup *root_cgrp = &root->top_cgroup; - struct cgroupfs_root *existing_root; - const struct cred *cred; - int i; - struct css_set *cset; - - BUG_ON(sb->s_root != NULL); - - ret = cgroup_get_rootdir(sb); - if (ret) - goto drop_new_super; - inode = sb->s_root->d_inode; - - mutex_lock(&inode->i_mutex); - mutex_lock(&cgroup_mutex); - mutex_lock(&cgroup_root_mutex); - - /* Check for name clashes with existing mounts */ - ret = -EBUSY; - if (strlen(root->name)) - for_each_active_root(existing_root) - if (!strcmp(existing_root->name, root->name)) - goto unlock_drop; - - /* - * We're accessing css_set_count without locking - * css_set_lock here, but that's OK - it can only be - * increased by someone holding cgroup_lock, and - * that's us. The worst that can happen is that we - * have some link structures left over - */ - ret = allocate_cgrp_cset_links(css_set_count, &tmp_links); - if (ret) - goto unlock_drop; - - /* ID 0 is reserved for dummy root, 1 for unified hierarchy */ - ret = cgroup_init_root_id(root, 2, 0); - if (ret) - goto unlock_drop; - - ret = rebind_subsystems(root, root->subsys_mask, 0); - if (ret == -EBUSY) { - free_cgrp_cset_links(&tmp_links); - goto unlock_drop; - } - /* - * There must be no failure case after here, since rebinding - * takes care of subsystems' refcounts, which are explicitly - * dropped in the failure exit path. - */ - - /* EBUSY should be the only error here */ - BUG_ON(ret); - - list_add(&root->root_list, &cgroup_roots); - cgroup_root_count++; - - sb->s_root->d_fsdata = root_cgrp; - root->top_cgroup.dentry = sb->s_root; - - /* Link the top cgroup in this hierarchy into all - * the css_set objects */ - write_lock(&css_set_lock); - hash_for_each(css_set_table, i, cset, hlist) - link_css_set(&tmp_links, cset, root_cgrp); - write_unlock(&css_set_lock); - - free_cgrp_cset_links(&tmp_links); - - BUG_ON(!list_empty(&root_cgrp->children)); - BUG_ON(root->number_of_cgroups != 1); - - cred = override_creds(&init_cred); - cgroup_populate_dir(root_cgrp, true, root->subsys_mask); - revert_creds(cred); - mutex_unlock(&cgroup_root_mutex); - mutex_unlock(&cgroup_mutex); - mutex_unlock(&inode->i_mutex); - } else { - /* - * We re-used an existing hierarchy - the new root (if - * any) is not needed - */ - cgroup_free_root(opts.new_root); - - if ((root->flags ^ opts.flags) & CGRP_ROOT_OPTION_MASK) { - if ((root->flags | opts.flags) & CGRP_ROOT_SANE_BEHAVIOR) { - pr_err("cgroup: sane_behavior: new mount options should match the existing superblock\n"); - ret = -EINVAL; - goto drop_new_super; - } else { - pr_warning("cgroup: new mount options do not match the existing superblock, will be ignored\n"); - } - } - - /* no subsys rebinding, so refcounts don't change */ - drop_parsed_module_refcounts(opts.subsys_mask); - } - - kfree(opts.release_agent); - kfree(opts.name); - return dget(sb->s_root); - - unlock_drop: - cgroup_exit_root_id(root); - mutex_unlock(&cgroup_root_mutex); - mutex_unlock(&cgroup_mutex); - mutex_unlock(&inode->i_mutex); - drop_new_super: - deactivate_locked_super(sb); - drop_modules: - drop_parsed_module_refcounts(opts.subsys_mask); - out_err: - kfree(opts.release_agent); - kfree(opts.name); - return ERR_PTR(ret); -} - -static void cgroup_kill_sb(struct super_block *sb) { - struct cgroupfs_root *root = sb->s_fs_info; - struct cgroup *cgrp = &root->top_cgroup; - struct cgrp_cset_link *link, *tmp_link; - int ret; - - BUG_ON(!root); - - BUG_ON(root->number_of_cgroups != 1); - BUG_ON(!list_empty(&cgrp->children)); - - mutex_lock(&cgroup_mutex); - mutex_lock(&cgroup_root_mutex); - - /* Rebind all subsystems back to the default hierarchy */ - if (root->flags & CGRP_ROOT_SUBSYS_BOUND) { - ret = rebind_subsystems(root, 0, root->subsys_mask); - /* Shouldn't be able to fail ... */ - BUG_ON(ret); - } - - /* - * Release all the links from cset_links to this hierarchy's - * root cgroup - */ - write_lock(&css_set_lock); - - list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) { - list_del(&link->cset_link); - list_del(&link->cgrp_link); - kfree(link); - } - write_unlock(&css_set_lock); - - if (!list_empty(&root->root_list)) { - list_del(&root->root_list); - cgroup_root_count--; - } - - cgroup_exit_root_id(root); - - mutex_unlock(&cgroup_root_mutex); - mutex_unlock(&cgroup_mutex); - - simple_xattrs_free(&cgrp->xattrs); - - kill_litter_super(sb); - cgroup_free_root(root); -} - -static struct file_system_type cgroup_fs_type = { - .name = "cgroup", - .mount = cgroup_mount, - .kill_sb = cgroup_kill_sb, -}; - -static struct kobject *cgroup_kobj; - -/** - * cgroup_path - generate the path of a cgroup - * @cgrp: the cgroup in question - * @buf: the buffer to write the path into - * @buflen: the length of the buffer - * - * Writes path of cgroup into buf. Returns 0 on success, -errno on error. - * - * We can't generate cgroup path using dentry->d_name, as accessing - * dentry->name must be protected by irq-unsafe dentry->d_lock or parent - * inode's i_mutex, while on the other hand cgroup_path() can be called - * with some irq-safe spinlocks held. - */ -int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) -{ - int ret = -ENAMETOOLONG; - char *start; - - if (!cgrp->parent) { - if (strlcpy(buf, "/", buflen) >= buflen) - return -ENAMETOOLONG; - return 0; - } - - start = buf + buflen - 1; - *start = '\0'; - - rcu_read_lock(); - do { - const char *name = cgroup_name(cgrp); - int len; - - len = strlen(name); - if ((start -= len) < buf) - goto out; - memcpy(start, name, len); - - if (--start < buf) - goto out; - *start = '/'; - - cgrp = cgrp->parent; - } while (cgrp->parent); - ret = 0; - memmove(buf, start, buf + buflen - start); -out: - rcu_read_unlock(); - return ret; -} -EXPORT_SYMBOL_GPL(cgroup_path); - -/** - * task_cgroup_path_from_hierarchy - cgroup path of a task on a hierarchy - * @task: target task - * @hierarchy_id: the hierarchy to look up @task's cgroup from - * @buf: the buffer to write the path into - * @buflen: the length of the buffer - * - * Determine @task's cgroup on the hierarchy specified by @hierarchy_id and - * copy its path into @buf. This function grabs cgroup_mutex and shouldn't - * be used inside locks used by cgroup controller callbacks. - */ -int task_cgroup_path_from_hierarchy(struct task_struct *task, int hierarchy_id, - char *buf, size_t buflen) -{ - struct cgroupfs_root *root; - struct cgroup *cgrp = NULL; - int ret = -ENOENT; - - mutex_lock(&cgroup_mutex); - - root = idr_find(&cgroup_hierarchy_idr, hierarchy_id); - if (root) { - cgrp = task_cgroup_from_root(task, root); - ret = cgroup_path(cgrp, buf, buflen); - } - - mutex_unlock(&cgroup_mutex); - - return ret; -} -EXPORT_SYMBOL_GPL(task_cgroup_path_from_hierarchy); - -/* - * Control Group taskset - */ -struct task_and_cgroup { - struct task_struct *task; - struct cgroup *cgrp; - struct css_set *cg; -}; - -struct cgroup_taskset { - struct task_and_cgroup single; - struct flex_array *tc_array; - int tc_array_len; - int idx; - struct cgroup *cur_cgrp; -}; - -/** - * cgroup_taskset_first - reset taskset and return the first task - * @tset: taskset of interest - * - * @tset iteration is initialized and the first task is returned. - */ -struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset) -{ - if (tset->tc_array) { - tset->idx = 0; - return cgroup_taskset_next(tset); - } else { - tset->cur_cgrp = tset->single.cgrp; - return tset->single.task; - } -} -EXPORT_SYMBOL_GPL(cgroup_taskset_first); - -/** - * cgroup_taskset_next - iterate to the next task in taskset - * @tset: taskset of interest - * - * Return the next task in @tset. Iteration must have been initialized - * with cgroup_taskset_first(). - */ -struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset) -{ - struct task_and_cgroup *tc; - - if (!tset->tc_array || tset->idx >= tset->tc_array_len) - return NULL; - - tc = flex_array_get(tset->tc_array, tset->idx++); - tset->cur_cgrp = tc->cgrp; - return tc->task; -} -EXPORT_SYMBOL_GPL(cgroup_taskset_next); - -/** - * cgroup_taskset_cur_cgroup - return the matching cgroup for the current task - * @tset: taskset of interest - * - * Return the cgroup for the current (last returned) task of @tset. This - * function must be preceded by either cgroup_taskset_first() or - * cgroup_taskset_next(). - */ -struct cgroup *cgroup_taskset_cur_cgroup(struct cgroup_taskset *tset) -{ - return tset->cur_cgrp; -} -EXPORT_SYMBOL_GPL(cgroup_taskset_cur_cgroup); - -/** - * cgroup_taskset_size - return the number of tasks in taskset - * @tset: taskset of interest - */ -int cgroup_taskset_size(struct cgroup_taskset *tset) -{ - return tset->tc_array ? tset->tc_array_len : 1; -} -EXPORT_SYMBOL_GPL(cgroup_taskset_size); - - -/* - * cgroup_task_migrate - move a task from one cgroup to another. - * - * Must be called with cgroup_mutex and threadgroup locked. - */ -static void cgroup_task_migrate(struct cgroup *old_cgrp, - struct task_struct *tsk, - struct css_set *new_cset) -{ - struct css_set *old_cset; - - /* - * We are synchronized through threadgroup_lock() against PF_EXITING - * setting such that we can't race against cgroup_exit() changing the - * css_set to init_css_set and dropping the old one. - */ - WARN_ON_ONCE(tsk->flags & PF_EXITING); - old_cset = task_css_set(tsk); - - task_lock(tsk); - rcu_assign_pointer(tsk->cgroups, new_cset); - task_unlock(tsk); - - /* Update the css_set linked lists if we're using them */ - write_lock(&css_set_lock); - if (!list_empty(&tsk->cg_list)) - list_move(&tsk->cg_list, &new_cset->tasks); - write_unlock(&css_set_lock); - - /* - * We just gained a reference on old_cset by taking it from the - * task. As trading it for new_cset is protected by cgroup_mutex, - * we're safe to drop it here; it will be freed under RCU. - */ - set_bit(CGRP_RELEASABLE, &old_cgrp->flags); - put_css_set(old_cset); -} - -/** - * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup - * @cgrp: the cgroup to attach to - * @tsk: the task or the leader of the threadgroup to be attached - * @threadgroup: attach the whole threadgroup? - * - * Call holding cgroup_mutex and the group_rwsem of the leader. Will take - * task_lock of @tsk or each thread in the threadgroup individually in turn. - */ -static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, - bool threadgroup) -{ - int retval, i, group_size; - struct cgroup_subsys *ss, *failed_ss = NULL; - struct cgroupfs_root *root = cgrp->root; - /* threadgroup list cursor and array */ - struct task_struct *leader = tsk; - struct task_and_cgroup *tc; - struct flex_array *group; - struct cgroup_taskset tset = { }; - - /* - * step 0: in order to do expensive, possibly blocking operations for - * every thread, we cannot iterate the thread group list, since it needs - * rcu or tasklist locked. instead, build an array of all threads in the - * group - group_rwsem prevents new threads from appearing, and if - * threads exit, this will just be an over-estimate. - */ - if (threadgroup) - group_size = get_nr_threads(tsk); - else - group_size = 1; - /* flex_array supports very large thread-groups better than kmalloc. */ - group = flex_array_alloc(sizeof(*tc), group_size, GFP_KERNEL); - if (!group) - return -ENOMEM; - /* pre-allocate to guarantee space while iterating in rcu read-side. */ - retval = flex_array_prealloc(group, 0, group_size, GFP_KERNEL); - if (retval) - goto out_free_group_list; - - i = 0; - /* - * Prevent freeing of tasks while we take a snapshot. Tasks that are - * already PF_EXITING could be freed from underneath us unless we - * take an rcu_read_lock. - */ - rcu_read_lock(); - do { - struct task_and_cgroup ent; - - /* @tsk either already exited or can't exit until the end */ - if (tsk->flags & PF_EXITING) - continue; - - /* as per above, nr_threads may decrease, but not increase. */ - BUG_ON(i >= group_size); - ent.task = tsk; - ent.cgrp = task_cgroup_from_root(tsk, root); - /* nothing to do if this task is already in the cgroup */ - if (ent.cgrp == cgrp) - continue; - /* - * saying GFP_ATOMIC has no effect here because we did prealloc - * earlier, but it's good form to communicate our expectations. - */ - retval = flex_array_put(group, i, &ent, GFP_ATOMIC); - BUG_ON(retval != 0); - i++; - - if (!threadgroup) - break; - } while_each_thread(leader, tsk); - rcu_read_unlock(); - /* remember the number of threads in the array for later. */ - group_size = i; - tset.tc_array = group; - tset.tc_array_len = group_size; - - /* methods shouldn't be called if no task is actually migrating */ - retval = 0; - if (!group_size) - goto out_free_group_list; - - /* - * step 1: check that we can legitimately attach to the cgroup. - */ - for_each_root_subsys(root, ss) { - if (ss->can_attach) { - retval = ss->can_attach(cgrp, &tset); - if (retval) { - failed_ss = ss; - goto out_cancel_attach; - } - } - } - - /* - * step 2: make sure css_sets exist for all threads to be migrated. - * we use find_css_set, which allocates a new one if necessary. - */ - for (i = 0; i < group_size; i++) { - struct css_set *old_cset; - - tc = flex_array_get(group, i); - old_cset = task_css_set(tc->task); - tc->cg = find_css_set(old_cset, cgrp); - if (!tc->cg) { - retval = -ENOMEM; - goto out_put_css_set_refs; - } - } - - /* - * step 3: now that we're guaranteed success wrt the css_sets, - * proceed to move all tasks to the new cgroup. There are no - * failure cases after here, so this is the commit point. - */ - for (i = 0; i < group_size; i++) { - tc = flex_array_get(group, i); - cgroup_task_migrate(tc->cgrp, tc->task, tc->cg); - } - /* nothing is sensitive to fork() after this point. */ - - /* - * step 4: do subsystem attach callbacks. - */ - for_each_root_subsys(root, ss) { - if (ss->attach) - ss->attach(cgrp, &tset); - } - - /* - * step 5: success! and cleanup - */ - retval = 0; -out_put_css_set_refs: - if (retval) { - for (i = 0; i < group_size; i++) { - tc = flex_array_get(group, i); - if (!tc->cg) - break; - put_css_set(tc->cg); - } - } -out_cancel_attach: - if (retval) { - for_each_root_subsys(root, ss) { - if (ss == failed_ss) - break; - if (ss->cancel_attach) - ss->cancel_attach(cgrp, &tset); - } - } -out_free_group_list: - flex_array_free(group); - return retval; -} - -/* - * Find the task_struct of the task to attach by vpid and pass it along to the - * function to attach either it or all tasks in its threadgroup. Will lock - * cgroup_mutex and threadgroup; may take task_lock of task. - */ -static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup) -{ - struct task_struct *tsk; - const struct cred *cred = current_cred(), *tcred; - int ret; - - if (!cgroup_lock_live_group(cgrp)) - return -ENODEV; - -retry_find_task: - rcu_read_lock(); - if (pid) { - tsk = find_task_by_vpid(pid); - if (!tsk) { - rcu_read_unlock(); - ret= -ESRCH; - goto out_unlock_cgroup; - } - /* - * even if we're attaching all tasks in the thread group, we - * only need to check permissions on one of them. - */ - tcred = __task_cred(tsk); - if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) && - !uid_eq(cred->euid, tcred->uid) && - !uid_eq(cred->euid, tcred->suid)) { - rcu_read_unlock(); - ret = -EACCES; - goto out_unlock_cgroup; - } - } else - tsk = current; - - if (threadgroup) - tsk = tsk->group_leader; - - /* - * Workqueue threads may acquire PF_NO_SETAFFINITY and become - * trapped in a cpuset, or RT worker may be born in a cgroup - * with no rt_runtime allocated. Just say no. - */ - if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) { - ret = -EINVAL; - rcu_read_unlock(); - goto out_unlock_cgroup; - } - - get_task_struct(tsk); - rcu_read_unlock(); - - threadgroup_lock(tsk); - if (threadgroup) { - if (!thread_group_leader(tsk)) { - /* - * a race with de_thread from another thread's exec() - * may strip us of our leadership, if this happens, - * there is no choice but to throw this task away and - * try again; this is - * "double-double-toil-and-trouble-check locking". - */ - threadgroup_unlock(tsk); - put_task_struct(tsk); - goto retry_find_task; - } - } - - ret = cgroup_attach_task(cgrp, tsk, threadgroup); - - threadgroup_unlock(tsk); - - put_task_struct(tsk); -out_unlock_cgroup: - mutex_unlock(&cgroup_mutex); - return ret; -} - -/** - * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' - * @from: attach to all cgroups of a given task - * @tsk: the task to be attached - */ -int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) -{ - struct cgroupfs_root *root; - int retval = 0; - - mutex_lock(&cgroup_mutex); - for_each_active_root(root) { - struct cgroup *from_cg = task_cgroup_from_root(from, root); - - retval = cgroup_attach_task(from_cg, tsk, false); - if (retval) - break; - } - mutex_unlock(&cgroup_mutex); - - return retval; -} -EXPORT_SYMBOL_GPL(cgroup_attach_task_all); - -static int cgroup_tasks_write(struct cgroup *cgrp, struct cftype *cft, u64 pid) -{ - return attach_task_by_pid(cgrp, pid, false); -} - -static int cgroup_procs_write(struct cgroup *cgrp, struct cftype *cft, u64 tgid) -{ - return attach_task_by_pid(cgrp, tgid, true); -} - -static int cgroup_release_agent_write(struct cgroup *cgrp, struct cftype *cft, - const char *buffer) -{ - BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); - if (strlen(buffer) >= PATH_MAX) - return -EINVAL; - if (!cgroup_lock_live_group(cgrp)) - return -ENODEV; - mutex_lock(&cgroup_root_mutex); - strcpy(cgrp->root->release_agent_path, buffer); - mutex_unlock(&cgroup_root_mutex); - mutex_unlock(&cgroup_mutex); - 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'); - mutex_unlock(&cgroup_mutex); - return 0; -} - -static int cgroup_sane_behavior_show(struct cgroup *cgrp, struct cftype *cft, - struct seq_file *seq) -{ - seq_printf(seq, "%d\n", cgroup_sane_behavior(cgrp)); - return 0; -} - -/* A buffer size big enough for numbers or short strings */ -#define CGROUP_LOCAL_BUFFER_SIZE 64 - -static ssize_t cgroup_write_X64(struct cgroup *cgrp, struct cftype *cft, - struct file *file, - const char __user *userbuf, - size_t nbytes, loff_t *unused_ppos) -{ - char buffer[CGROUP_LOCAL_BUFFER_SIZE]; - int retval = 0; - char *end; - - if (!nbytes) - return -EINVAL; - if (nbytes >= sizeof(buffer)) - return -E2BIG; - if (copy_from_user(buffer, userbuf, nbytes)) - return -EFAULT; - - buffer[nbytes] = 0; /* nul-terminate */ - if (cft->write_u64) { - u64 val = simple_strtoull(strstrip(buffer), &end, 0); - if (*end) - return -EINVAL; - retval = cft->write_u64(cgrp, cft, val); - } else { - s64 val = simple_strtoll(strstrip(buffer), &end, 0); - if (*end) - return -EINVAL; - retval = cft->write_s64(cgrp, cft, val); - } - if (!retval) - retval = nbytes; - return retval; -} - -static ssize_t cgroup_write_string(struct cgroup *cgrp, struct cftype *cft, - struct file *file, - const char __user *userbuf, - size_t nbytes, loff_t *unused_ppos) -{ - char local_buffer[CGROUP_LOCAL_BUFFER_SIZE]; - int retval = 0; - size_t max_bytes = cft->max_write_len; - char *buffer = local_buffer; - - if (!max_bytes) - max_bytes = sizeof(local_buffer) - 1; - if (nbytes >= max_bytes) - return -E2BIG; - /* Allocate a dynamic buffer if we need one */ - if (nbytes >= sizeof(local_buffer)) { - buffer = kmalloc(nbytes + 1, GFP_KERNEL); - if (buffer == NULL) - return -ENOMEM; - } - if (nbytes && copy_from_user(buffer, userbuf, nbytes)) { - retval = -EFAULT; - goto out; - } - - buffer[nbytes] = 0; /* nul-terminate */ - retval = cft->write_string(cgrp, cft, strstrip(buffer)); - if (!retval) - retval = nbytes; -out: - if (buffer != local_buffer) - kfree(buffer); - return retval; -} - -static ssize_t cgroup_file_write(struct file *file, const char __user *buf, - size_t nbytes, loff_t *ppos) -{ - struct cftype *cft = __d_cft(file->f_dentry); - struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); - - if (cgroup_is_dead(cgrp)) - return -ENODEV; - if (cft->write) - return cft->write(cgrp, cft, file, buf, nbytes, ppos); - if (cft->write_u64 || cft->write_s64) - return cgroup_write_X64(cgrp, cft, file, buf, nbytes, ppos); - if (cft->write_string) - return cgroup_write_string(cgrp, cft, file, buf, nbytes, ppos); - if (cft->trigger) { - int ret = cft->trigger(cgrp, (unsigned int)cft->private); - return ret ? ret : nbytes; - } - return -EINVAL; -} - -static ssize_t cgroup_read_u64(struct cgroup *cgrp, struct cftype *cft, - struct file *file, - char __user *buf, size_t nbytes, - loff_t *ppos) -{ - char tmp[CGROUP_LOCAL_BUFFER_SIZE]; - u64 val = cft->read_u64(cgrp, cft); - int len = sprintf(tmp, "%llu\n", (unsigned long long) val); - - return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); -} - -static ssize_t cgroup_read_s64(struct cgroup *cgrp, struct cftype *cft, - struct file *file, - char __user *buf, size_t nbytes, - loff_t *ppos) -{ - char tmp[CGROUP_LOCAL_BUFFER_SIZE]; - s64 val = cft->read_s64(cgrp, cft); - int len = sprintf(tmp, "%lld\n", (long long) val); - - return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); -} - -static ssize_t cgroup_file_read(struct file *file, char __user *buf, - size_t nbytes, loff_t *ppos) -{ - struct cftype *cft = __d_cft(file->f_dentry); - struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); - - if (cgroup_is_dead(cgrp)) - return -ENODEV; - - if (cft->read) - return cft->read(cgrp, cft, file, buf, nbytes, ppos); - if (cft->read_u64) - return cgroup_read_u64(cgrp, cft, file, buf, nbytes, ppos); - if (cft->read_s64) - return cgroup_read_s64(cgrp, cft, file, buf, nbytes, ppos); - return -EINVAL; -} - -/* - * seqfile ops/methods for returning structured data. Currently just - * supports string->u64 maps, but can be extended in future. - */ - -struct cgroup_seqfile_state { - struct cftype *cft; - struct cgroup *cgroup; -}; - -static int cgroup_map_add(struct cgroup_map_cb *cb, const char *key, u64 value) -{ - struct seq_file *sf = cb->state; - return seq_printf(sf, "%s %llu\n", key, (unsigned long long)value); -} - -static int cgroup_seqfile_show(struct seq_file *m, void *arg) -{ - struct cgroup_seqfile_state *state = m->private; - struct cftype *cft = state->cft; - if (cft->read_map) { - struct cgroup_map_cb cb = { - .fill = cgroup_map_add, - .state = m, - }; - return cft->read_map(state->cgroup, cft, &cb); - } - return cft->read_seq_string(state->cgroup, cft, m); -} - -static int cgroup_seqfile_release(struct inode *inode, struct file *file) -{ - struct seq_file *seq = file->private_data; - kfree(seq->private); - return single_release(inode, file); -} - -static const struct file_operations cgroup_seqfile_operations = { - .read = seq_read, - .write = cgroup_file_write, - .llseek = seq_lseek, - .release = cgroup_seqfile_release, -}; - -static int cgroup_file_open(struct inode *inode, struct file *file) -{ - int err; - struct cftype *cft; - - err = generic_file_open(inode, file); - if (err) - return err; - cft = __d_cft(file->f_dentry); - - if (cft->read_map || cft->read_seq_string) { - struct cgroup_seqfile_state *state; - - 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) -{ - int ret; - struct cgroup_name *name, *old_name; - struct cgroup *cgrp; - - /* - * It's convinient to use parent dir's i_mutex to protected - * cgrp->name. - */ - lockdep_assert_held(&old_dir->i_mutex); - - 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; - - cgrp = __d_cgrp(old_dentry); - - /* - * This isn't a proper migration and its usefulness is very - * limited. Disallow if sane_behavior. - */ - if (cgroup_sane_behavior(cgrp)) - return -EPERM; - - name = cgroup_alloc_name(new_dentry); - if (!name) - return -ENOMEM; - - ret = simple_rename(old_dir, old_dentry, new_dir, new_dentry); - if (ret) { - kfree(name); - return ret; - } - - old_name = rcu_dereference_protected(cgrp->name, true); - rcu_assign_pointer(cgrp->name, name); - - kfree_rcu(old_name, rcu_head); - return 0; -} - -static struct simple_xattrs *__d_xattrs(struct dentry *dentry) -{ - if (S_ISDIR(dentry->d_inode->i_mode)) - return &__d_cgrp(dentry)->xattrs; - else - return &__d_cfe(dentry)->xattrs; -} - -static inline int xattr_enabled(struct dentry *dentry) -{ - struct cgroupfs_root *root = dentry->d_sb->s_fs_info; - return root->flags & CGRP_ROOT_XATTR; -} - -static bool is_valid_xattr(const char *name) -{ - if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) || - !strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) - return true; - return false; -} - -static int cgroup_setxattr(struct dentry *dentry, const char *name, - const void *val, size_t size, int flags) -{ - if (!xattr_enabled(dentry)) - return -EOPNOTSUPP; - if (!is_valid_xattr(name)) - return -EINVAL; - return simple_xattr_set(__d_xattrs(dentry), name, val, size, flags); -} - -static int cgroup_removexattr(struct dentry *dentry, const char *name) -{ - if (!xattr_enabled(dentry)) - return -EOPNOTSUPP; - if (!is_valid_xattr(name)) - return -EINVAL; - return simple_xattr_remove(__d_xattrs(dentry), name); -} - -static ssize_t cgroup_getxattr(struct dentry *dentry, const char *name, - void *buf, size_t size) -{ - if (!xattr_enabled(dentry)) - return -EOPNOTSUPP; - if (!is_valid_xattr(name)) - return -EINVAL; - return simple_xattr_get(__d_xattrs(dentry), name, buf, size); -} - -static ssize_t cgroup_listxattr(struct dentry *dentry, char *buf, size_t size) -{ - if (!xattr_enabled(dentry)) - return -EOPNOTSUPP; - return simple_xattr_list(__d_xattrs(dentry), buf, size); -} - -static const struct file_operations cgroup_file_operations = { - .read = cgroup_file_read, - .write = cgroup_file_write, - .llseek = generic_file_llseek, - .open = cgroup_file_open, - .release = cgroup_file_release, -}; - -static const struct inode_operations cgroup_file_inode_operations = { - .setxattr = cgroup_setxattr, - .getxattr = cgroup_getxattr, - .listxattr = cgroup_listxattr, - .removexattr = cgroup_removexattr, -}; - -static const struct inode_operations cgroup_dir_inode_operations = { - .lookup = simple_lookup, - .mkdir = cgroup_mkdir, - .rmdir = cgroup_rmdir, - .rename = cgroup_rename, - .setxattr = cgroup_setxattr, - .getxattr = cgroup_getxattr, - .listxattr = cgroup_listxattr, - .removexattr = cgroup_removexattr, -}; - -/* - * Check if a file is a control file - */ -static inline struct cftype *__file_cft(struct file *file) -{ - if (file_inode(file)->i_fop != &cgroup_file_operations) - return ERR_PTR(-EINVAL); - return __d_cft(file->f_dentry); -} - -static int cgroup_create_file(struct dentry *dentry, umode_t mode, - struct super_block *sb) -{ - struct inode *inode; - - if (!dentry) - return -ENOENT; - if (dentry->d_inode) - return -EEXIST; - - inode = cgroup_new_inode(mode, sb); - if (!inode) - return -ENOMEM; - - if (S_ISDIR(mode)) { - inode->i_op = &cgroup_dir_inode_operations; - inode->i_fop = &simple_dir_operations; - - /* start off with i_nlink == 2 (for "." entry) */ - inc_nlink(inode); - inc_nlink(dentry->d_parent->d_inode); - - /* - * Control reaches here with cgroup_mutex held. - * @inode->i_mutex should nest outside cgroup_mutex but we - * want to populate it immediately without releasing - * cgroup_mutex. As @inode isn't visible to anyone else - * yet, trylock will always succeed without affecting - * lockdep checks. - */ - WARN_ON_ONCE(!mutex_trylock(&inode->i_mutex)); - } else if (S_ISREG(mode)) { - inode->i_size = 0; - inode->i_fop = &cgroup_file_operations; - inode->i_op = &cgroup_file_inode_operations; - } - d_instantiate(dentry, inode); - dget(dentry); /* Extra count - pin the dentry in core */ - return 0; -} - -/** - * cgroup_file_mode - deduce file mode of a control file - * @cft: the control file in question - * - * returns cft->mode if ->mode is not 0 - * returns S_IRUGO|S_IWUSR if it has both a read and a write handler - * returns S_IRUGO if it has only a read handler - * returns S_IWUSR if it has only a write hander - */ -static umode_t cgroup_file_mode(const struct cftype *cft) -{ - umode_t mode = 0; - - if (cft->mode) - return cft->mode; - - if (cft->read || cft->read_u64 || cft->read_s64 || - cft->read_map || cft->read_seq_string) - mode |= S_IRUGO; - - if (cft->write || cft->write_u64 || cft->write_s64 || - cft->write_string || cft->trigger) - mode |= S_IWUSR; - - return mode; -} - -static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys, - struct cftype *cft) -{ - struct dentry *dir = cgrp->dentry; - struct cgroup *parent = __d_cgrp(dir); - struct dentry *dentry; - struct cfent *cfe; - int error; - umode_t mode; - char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 }; - - if (subsys && !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) { - strcpy(name, subsys->name); - strcat(name, "."); - } - strcat(name, cft->name); - - BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex)); - - cfe = kzalloc(sizeof(*cfe), GFP_KERNEL); - if (!cfe) - return -ENOMEM; - - dentry = lookup_one_len(name, dir, strlen(name)); - if (IS_ERR(dentry)) { - error = PTR_ERR(dentry); - goto out; - } - - cfe->type = (void *)cft; - cfe->dentry = dentry; - dentry->d_fsdata = cfe; - simple_xattrs_init(&cfe->xattrs); - - mode = cgroup_file_mode(cft); - error = cgroup_create_file(dentry, mode | S_IFREG, cgrp->root->sb); - if (!error) { - list_add_tail(&cfe->node, &parent->files); - cfe = NULL; - } - dput(dentry); -out: - kfree(cfe); - return error; -} - -static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys, - struct cftype cfts[], bool is_add) -{ - struct cftype *cft; - int err, ret = 0; - - for (cft = cfts; cft->name[0] != '\0'; cft++) { - /* does cft->flags tell us to skip this file on @cgrp? */ - if ((cft->flags & CFTYPE_INSANE) && cgroup_sane_behavior(cgrp)) - continue; - if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent) - continue; - if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent) - continue; - - if (is_add) { - err = cgroup_add_file(cgrp, subsys, cft); - if (err) - pr_warn("cgroup_addrm_files: failed to add %s, err=%d\n", - cft->name, err); - ret = err; - } else { - cgroup_rm_file(cgrp, cft); - } - } - return ret; -} - -static void cgroup_cfts_prepare(void) - __acquires(&cgroup_mutex) -{ - /* - * Thanks to the entanglement with vfs inode locking, we can't walk - * the existing cgroups under cgroup_mutex and create files. - * Instead, we use cgroup_for_each_descendant_pre() and drop RCU - * read lock before calling cgroup_addrm_files(). - */ - mutex_lock(&cgroup_mutex); -} - -static void cgroup_cfts_commit(struct cgroup_subsys *ss, - struct cftype *cfts, bool is_add) - __releases(&cgroup_mutex) -{ - LIST_HEAD(pending); - struct cgroup *cgrp, *root = &ss->root->top_cgroup; - struct super_block *sb = ss->root->sb; - struct dentry *prev = NULL; - struct inode *inode; - u64 update_before; - - /* %NULL @cfts indicates abort and don't bother if @ss isn't attached */ - if (!cfts || ss->root == &cgroup_dummy_root || - !atomic_inc_not_zero(&sb->s_active)) { - mutex_unlock(&cgroup_mutex); - return; - } - - /* - * All cgroups which are created after we drop cgroup_mutex will - * have the updated set of files, so we only need to update the - * cgroups created before the current @cgroup_serial_nr_next. - */ - update_before = cgroup_serial_nr_next; - - mutex_unlock(&cgroup_mutex); - - /* @root always needs to be updated */ - inode = root->dentry->d_inode; - mutex_lock(&inode->i_mutex); - mutex_lock(&cgroup_mutex); - cgroup_addrm_files(root, ss, cfts, is_add); - mutex_unlock(&cgroup_mutex); - mutex_unlock(&inode->i_mutex); - - /* add/rm files for all cgroups created before */ - rcu_read_lock(); - cgroup_for_each_descendant_pre(cgrp, root) { - if (cgroup_is_dead(cgrp)) - continue; - - inode = cgrp->dentry->d_inode; - dget(cgrp->dentry); - rcu_read_unlock(); - - dput(prev); - prev = cgrp->dentry; - - mutex_lock(&inode->i_mutex); - mutex_lock(&cgroup_mutex); - if (cgrp->serial_nr < update_before && !cgroup_is_dead(cgrp)) - cgroup_addrm_files(cgrp, ss, cfts, is_add); - mutex_unlock(&cgroup_mutex); - mutex_unlock(&inode->i_mutex); - - rcu_read_lock(); - } - rcu_read_unlock(); - dput(prev); - deactivate_super(sb); -} - -/** - * cgroup_add_cftypes - add an array of cftypes to a subsystem - * @ss: target cgroup subsystem - * @cfts: zero-length name terminated array of cftypes - * - * Register @cfts to @ss. Files described by @cfts are created for all - * existing cgroups to which @ss is attached and all future cgroups will - * have them too. This function can be called anytime whether @ss is - * attached or not. - * - * Returns 0 on successful registration, -errno on failure. Note that this - * function currently returns 0 as long as @cfts registration is successful - * even if some file creation attempts on existing cgroups fail. - */ -int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) -{ - struct cftype_set *set; - - set = kzalloc(sizeof(*set), GFP_KERNEL); - if (!set) - return -ENOMEM; - - cgroup_cfts_prepare(); - set->cfts = cfts; - list_add_tail(&set->node, &ss->cftsets); - cgroup_cfts_commit(ss, cfts, true); - - return 0; -} -EXPORT_SYMBOL_GPL(cgroup_add_cftypes); - -/** - * cgroup_rm_cftypes - remove an array of cftypes from a subsystem - * @ss: target cgroup subsystem - * @cfts: zero-length name terminated array of cftypes - * - * Unregister @cfts from @ss. Files described by @cfts are removed from - * all existing cgroups to which @ss is attached and all future cgroups - * won't have them either. This function can be called anytime whether @ss - * is attached or not. - * - * Returns 0 on successful unregistration, -ENOENT if @cfts is not - * registered with @ss. - */ -int cgroup_rm_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) -{ - struct cftype_set *set; - - cgroup_cfts_prepare(); - - list_for_each_entry(set, &ss->cftsets, node) { - if (set->cfts == cfts) { - list_del(&set->node); - kfree(set); - cgroup_cfts_commit(ss, cfts, false); - return 0; - } - } - - cgroup_cfts_commit(ss, NULL, false); - return -ENOENT; -} - -/** - * cgroup_task_count - count the number of tasks in a cgroup. - * @cgrp: the cgroup in question - * - * Return the number of tasks in the cgroup. - */ -int cgroup_task_count(const struct cgroup *cgrp) -{ - int count = 0; - struct cgrp_cset_link *link; - - read_lock(&css_set_lock); - list_for_each_entry(link, &cgrp->cset_links, cset_link) - count += atomic_read(&link->cset->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->cset_link; - struct cgrp_cset_link *link; - struct css_set *cset; - - /* Advance to the next non-empty css_set */ - do { - l = l->next; - if (l == &cgrp->cset_links) { - it->cset_link = NULL; - return; - } - link = list_entry(l, struct cgrp_cset_link, cset_link); - cset = link->cset; - } while (list_empty(&cset->tasks)); - it->cset_link = l; - it->task = cset->tasks.next; -} - -/* - * To reduce the fork() overhead for systems that are not actually - * using their cgroups capability, we don't maintain the lists running - * through each css_set to its tasks until we see the list actually - * used - in other words after the first call to cgroup_iter_start(). - */ -static void cgroup_enable_task_cg_lists(void) -{ - struct task_struct *p, *g; - write_lock(&css_set_lock); - use_task_css_set_links = 1; - /* - * We need tasklist_lock because RCU is not safe against - * while_each_thread(). Besides, a forking task that has passed - * cgroup_post_fork() without seeing use_task_css_set_links = 1 - * is not guaranteed to have its child immediately visible in the - * tasklist if we walk through it with RCU. - */ - read_lock(&tasklist_lock); - do_each_thread(g, p) { - task_lock(p); - /* - * We should check if the process is exiting, otherwise - * it will race with cgroup_exit() in that the list - * entry won't be deleted though the process has exited. - */ - if (!(p->flags & PF_EXITING) && list_empty(&p->cg_list)) - list_add(&p->cg_list, &task_css_set(p)->tasks); - task_unlock(p); - } while_each_thread(g, p); - read_unlock(&tasklist_lock); - write_unlock(&css_set_lock); -} - -/** - * cgroup_next_sibling - find the next sibling of a given cgroup - * @pos: the current cgroup - * - * This function returns the next sibling of @pos and should be called - * under RCU read lock. The only requirement is that @pos is accessible. - * The next sibling is guaranteed to be returned regardless of @pos's - * state. - */ -struct cgroup *cgroup_next_sibling(struct cgroup *pos) -{ - struct cgroup *next; - - WARN_ON_ONCE(!rcu_read_lock_held()); - - /* - * @pos could already have been removed. Once a cgroup is removed, - * its ->sibling.next is no longer updated when its next sibling - * changes. As CGRP_DEAD assertion is serialized and happens - * before the cgroup is taken off the ->sibling list, if we see it - * unasserted, it's guaranteed that the next sibling hasn't - * finished its grace period even if it's already removed, and thus - * safe to dereference from this RCU critical section. If - * ->sibling.next is inaccessible, cgroup_is_dead() is guaranteed - * to be visible as %true here. - */ - if (likely(!cgroup_is_dead(pos))) { - next = list_entry_rcu(pos->sibling.next, struct cgroup, sibling); - if (&next->sibling != &pos->parent->children) - return next; - return NULL; - } - - /* - * Can't dereference the next pointer. Each cgroup is given a - * monotonically increasing unique serial number and always - * appended to the sibling list, so the next one can be found by - * walking the parent's children until we see a cgroup with higher - * serial number than @pos's. - * - * While this path can be slow, it's taken only when either the - * current cgroup is removed or iteration and removal race. - */ - list_for_each_entry_rcu(next, &pos->parent->children, sibling) - if (next->serial_nr > pos->serial_nr) - return next; - return NULL; -} -EXPORT_SYMBOL_GPL(cgroup_next_sibling); - -/** - * cgroup_next_descendant_pre - find the next descendant for pre-order walk - * @pos: the current position (%NULL to initiate traversal) - * @cgroup: cgroup whose descendants to walk - * - * To be used by cgroup_for_each_descendant_pre(). Find the next - * descendant to visit for pre-order traversal of @cgroup's descendants. - * - * While this function requires RCU read locking, it doesn't require the - * whole traversal to be contained in a single RCU critical section. This - * function will return the correct next descendant as long as both @pos - * and @cgroup are accessible and @pos is a descendant of @cgroup. - */ -struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos, - struct cgroup *cgroup) -{ - struct cgroup *next; - - WARN_ON_ONCE(!rcu_read_lock_held()); - - /* if first iteration, pretend we just visited @cgroup */ - if (!pos) - pos = cgroup; - - /* visit the first child if exists */ - next = list_first_or_null_rcu(&pos->children, struct cgroup, sibling); - if (next) - return next; - - /* no child, visit my or the closest ancestor's next sibling */ - while (pos != cgroup) { - next = cgroup_next_sibling(pos); - if (next) - return next; - pos = pos->parent; - } - - return NULL; -} -EXPORT_SYMBOL_GPL(cgroup_next_descendant_pre); - -/** - * cgroup_rightmost_descendant - return the rightmost descendant of a cgroup - * @pos: cgroup of interest - * - * Return the rightmost descendant of @pos. If there's no descendant, - * @pos is returned. This can be used during pre-order traversal to skip - * subtree of @pos. - * - * While this function requires RCU read locking, it doesn't require the - * whole traversal to be contained in a single RCU critical section. This - * function will return the correct rightmost descendant as long as @pos is - * accessible. - */ -struct cgroup *cgroup_rightmost_descendant(struct cgroup *pos) -{ - struct cgroup *last, *tmp; - - WARN_ON_ONCE(!rcu_read_lock_held()); - - do { - last = pos; - /* ->prev isn't RCU safe, walk ->next till the end */ - pos = NULL; - list_for_each_entry_rcu(tmp, &last->children, sibling) - pos = tmp; - } while (pos); - - return last; -} -EXPORT_SYMBOL_GPL(cgroup_rightmost_descendant); - -static struct cgroup *cgroup_leftmost_descendant(struct cgroup *pos) -{ - struct cgroup *last; - - do { - last = pos; - pos = list_first_or_null_rcu(&pos->children, struct cgroup, - sibling); - } while (pos); - - return last; -} - -/** - * cgroup_next_descendant_post - find the next descendant for post-order walk - * @pos: the current position (%NULL to initiate traversal) - * @cgroup: cgroup whose descendants to walk - * - * To be used by cgroup_for_each_descendant_post(). Find the next - * descendant to visit for post-order traversal of @cgroup's descendants. - * - * While this function requires RCU read locking, it doesn't require the - * whole traversal to be contained in a single RCU critical section. This - * function will return the correct next descendant as long as both @pos - * and @cgroup are accessible and @pos is a descendant of @cgroup. - */ -struct cgroup *cgroup_next_descendant_post(struct cgroup *pos, - struct cgroup *cgroup) -{ - struct cgroup *next; - - WARN_ON_ONCE(!rcu_read_lock_held()); - - /* if first iteration, visit the leftmost descendant */ - if (!pos) { - next = cgroup_leftmost_descendant(cgroup); - return next != cgroup ? next : NULL; - } - - /* if there's an unvisited sibling, visit its leftmost descendant */ - next = cgroup_next_sibling(pos); - if (next) - return cgroup_leftmost_descendant(next); - - /* no sibling left, visit parent */ - next = pos->parent; - return next != cgroup ? next : NULL; -} -EXPORT_SYMBOL_GPL(cgroup_next_descendant_post); - -void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it) - __acquires(css_set_lock) -{ - /* - * The first time anyone tries to iterate across a cgroup, - * we need to enable the list linking each css_set to its - * tasks, and fix up all existing tasks. - */ - if (!use_task_css_set_links) - cgroup_enable_task_cg_lists(); - - read_lock(&css_set_lock); - it->cset_link = &cgrp->cset_links; - cgroup_advance_iter(cgrp, it); -} - -struct task_struct *cgroup_iter_next(struct cgroup *cgrp, - struct cgroup_iter *it) -{ - struct task_struct *res; - struct list_head *l = it->task; - struct cgrp_cset_link *link; - - /* If the iterator cg is NULL, we have no tasks */ - if (!it->cset_link) - return NULL; - res = list_entry(l, struct task_struct, cg_list); - /* Advance iterator to find next entry */ - l = l->next; - link = list_entry(it->cset_link, struct cgrp_cset_link, cset_link); - if (l == &link->cset->tasks) { - /* We reached the end of this task list - move on to - * the next cg_cgroup_link */ - cgroup_advance_iter(cgrp, it); - } else { - it->task = l; - } - return res; -} - -void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it) - __releases(css_set_lock) -{ - read_unlock(&css_set_lock); -} - -static inline int started_after_time(struct task_struct *t1, - struct timespec *time, - struct task_struct *t2) -{ - int start_diff = timespec_compare(&t1->start_time, time); - if (start_diff > 0) { - return 1; - } else if (start_diff < 0) { - return 0; - } else { - /* - * Arbitrarily, if two processes started at the same - * time, we'll say that the lower pointer value - * started first. Note that t2 may have exited by now - * so this may not be a valid pointer any longer, but - * that's fine - it still serves to distinguish - * between two tasks started (effectively) simultaneously. - */ - return t1 > t2; - } -} - -/* - * This function is a callback from heap_insert() and is used to order - * the heap. - * In this case we order the heap in descending task start time. - */ -static inline int started_after(void *p1, void *p2) -{ - struct task_struct *t1 = p1; - struct task_struct *t2 = p2; - return started_after_time(t1, &t2->start_time, t2); -} - -/** - * cgroup_scan_tasks - iterate though all the tasks in a cgroup - * @scan: struct cgroup_scanner containing arguments for the scan - * - * Arguments include pointers to callback functions test_task() and - * process_task(). - * Iterate through all the tasks in a cgroup, calling test_task() for each, - * and if it returns true, call process_task() for it also. - * The test_task pointer may be NULL, meaning always true (select all tasks). - * Effectively duplicates cgroup_iter_{start,next,end}() - * but does not lock css_set_lock for the call to process_task(). - * The struct cgroup_scanner may be embedded in any structure of the caller's - * creation. - * It is guaranteed that process_task() will act on every task that - * is a member of the cgroup for the duration of this call. This - * function may or may not call process_task() for tasks that exit - * or move to a different cgroup during the call, or are forked or - * move into the cgroup during the call. - * - * Note that test_task() may be called with locks held, and may in some - * situations be called multiple times for the same task, so it should - * be cheap. - * If the heap pointer in the struct cgroup_scanner is non-NULL, a heap has been - * pre-allocated and will be used for heap operations (and its "gt" member will - * be overwritten), else a temporary heap will be used (allocation of which - * may cause this function to fail). - */ -int cgroup_scan_tasks(struct cgroup_scanner *scan) -{ - int retval, i; - struct cgroup_iter it; - struct task_struct *p, *dropped; - /* Never dereference latest_task, since it's not refcounted */ - struct task_struct *latest_task = NULL; - struct ptr_heap tmp_heap; - struct ptr_heap *heap; - struct timespec latest_time = { 0, 0 }; - - if (scan->heap) { - /* The caller supplied our heap and pre-allocated its memory */ - heap = scan->heap; - heap->gt = &started_after; - } else { - /* We need to allocate our own heap memory */ - heap = &tmp_heap; - retval = heap_init(heap, PAGE_SIZE, GFP_KERNEL, &started_after); - if (retval) - /* cannot allocate the heap */ - return retval; - } - - again: - /* - * Scan tasks in the cgroup, using the scanner's "test_task" callback - * to determine which are of interest, and using the scanner's - * "process_task" callback to process any of them that need an update. - * Since we don't want to hold any locks during the task updates, - * gather tasks to be processed in a heap structure. - * The heap is sorted by descending task start time. - * If the statically-sized heap fills up, we overflow tasks that - * started later, and in future iterations only consider tasks that - * started after the latest task in the previous pass. This - * guarantees forward progress and that we don't miss any tasks. - */ - heap->size = 0; - cgroup_iter_start(scan->cg, &it); - while ((p = cgroup_iter_next(scan->cg, &it))) { - /* - * Only affect tasks that qualify per the caller's callback, - * if he provided one - */ - if (scan->test_task && !scan->test_task(p, scan)) - continue; - /* - * Only process tasks that started after the last task - * we processed - */ - if (!started_after_time(p, &latest_time, latest_task)) - continue; - dropped = heap_insert(heap, p); - if (dropped == NULL) { - /* - * The new task was inserted; the heap wasn't - * previously full - */ - get_task_struct(p); - } else if (dropped != p) { - /* - * The new task was inserted, and pushed out a - * different task - */ - get_task_struct(p); - put_task_struct(dropped); - } - /* - * Else the new task was newer than anything already in - * the heap and wasn't inserted - */ - } - cgroup_iter_end(scan->cg, &it); - - if (heap->size) { - for (i = 0; i < heap->size; i++) { - struct task_struct *q = heap->ptrs[i]; - if (i == 0) { - latest_time = q->start_time; - latest_task = q; - } - /* Process the task per the caller's callback */ - scan->process_task(q, scan); - put_task_struct(q); - } - /* - * If we had to process any tasks at all, scan again - * in case some of them were in the middle of forking - * children that didn't get processed. - * Not the most efficient way to do it, but it avoids - * having to take callback_mutex in the fork path - */ - goto again; - } - if (heap == &tmp_heap) - heap_free(&tmp_heap); - return 0; -} - -static void cgroup_transfer_one_task(struct task_struct *task, - struct cgroup_scanner *scan) -{ - struct cgroup *new_cgroup = scan->data; - - mutex_lock(&cgroup_mutex); - cgroup_attach_task(new_cgroup, task, false); - mutex_unlock(&cgroup_mutex); -} - -/** - * cgroup_trasnsfer_tasks - move tasks from one cgroup to another - * @to: cgroup to which the tasks will be moved - * @from: cgroup in which the tasks currently reside - */ -int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) -{ - struct cgroup_scanner scan; - - scan.cg = from; - scan.test_task = NULL; /* select all tasks in cgroup */ - scan.process_task = cgroup_transfer_one_task; - scan.heap = NULL; - scan.data = to; - - return cgroup_scan_tasks(&scan); -} - -/* - * Stuff for reading the 'tasks'/'procs' files. - * - * Reading this file can return large amounts of data if a cgroup has - * *lots* of attached tasks. So it may need several calls to read(), - * but we cannot guarantee that the information we produce is correct - * unless we produce it entirely atomically. - * - */ - -/* which pidlist file are we talking about? */ -enum cgroup_filetype { - CGROUP_FILE_PROCS, - CGROUP_FILE_TASKS, -}; - -/* - * A pidlist is a list of pids that virtually represents the contents of one - * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists, - * a pair (one each for procs, tasks) for each pid namespace that's relevant - * to the cgroup. - */ -struct cgroup_pidlist { - /* - * used to find which pidlist is wanted. doesn't change as long as - * this particular list stays in the list. - */ - struct { enum cgroup_filetype type; struct pid_namespace *ns; } key; - /* array of xids */ - pid_t *list; - /* how many elements the above list has */ - int length; - /* how many files are using the current array */ - int use_count; - /* each of these stored in a list by its cgroup */ - struct list_head links; - /* pointer to the cgroup we belong to, for list removal purposes */ - struct cgroup *owner; - /* protects the other fields */ - struct rw_semaphore mutex; -}; - -/* - * The following two functions "fix" the issue where there are more pids - * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. - * TODO: replace with a kernel-wide solution to this problem - */ -#define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2)) -static void *pidlist_allocate(int count) -{ - if (PIDLIST_TOO_LARGE(count)) - return vmalloc(count * sizeof(pid_t)); - else - return kmalloc(count * sizeof(pid_t), GFP_KERNEL); -} -static void pidlist_free(void *p) -{ - if (is_vmalloc_addr(p)) - vfree(p); - else - kfree(p); -} - -/* - * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries - * Returns the number of unique elements. - */ -static int pidlist_uniq(pid_t *list, int length) -{ - int src, dest = 1; - - /* - * we presume the 0th element is unique, so i starts at 1. trivial - * edge cases first; no work needs to be done for either - */ - if (length == 0 || length == 1) - return length; - /* src and dest walk down the list; dest counts unique elements */ - for (src = 1; src < length; src++) { - /* find next unique element */ - while (list[src] == list[src-1]) { - src++; - if (src == length) - goto after; - } - /* dest always points to where the next unique element goes */ - list[dest] = list[src]; - dest++; - } -after: - return dest; -} - -static int cmppid(const void *a, const void *b) -{ - return *(pid_t *)a - *(pid_t *)b; -} - -/* - * find the appropriate pidlist for our purpose (given procs vs tasks) - * returns with the lock on that pidlist already held, and takes care - * of the use count, or returns NULL with no locks held if we're out of - * memory. - */ -static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, - enum cgroup_filetype type) -{ - struct cgroup_pidlist *l; - /* don't need task_nsproxy() if we're looking at ourself */ - struct pid_namespace *ns = task_active_pid_ns(current); - - /* - * We can't drop the pidlist_mutex before taking the l->mutex in case - * the last ref-holder is trying to remove l from the list at the same - * time. Holding the pidlist_mutex precludes somebody taking whichever - * list we find out from under us - compare release_pid_array(). - */ - mutex_lock(&cgrp->pidlist_mutex); - list_for_each_entry(l, &cgrp->pidlists, links) { - if (l->key.type == type && l->key.ns == ns) { - /* make sure l doesn't vanish out from under us */ - down_write(&l->mutex); - mutex_unlock(&cgrp->pidlist_mutex); - return l; - } - } - /* entry not found; create a new one */ - l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); - if (!l) { - mutex_unlock(&cgrp->pidlist_mutex); - return l; - } - init_rwsem(&l->mutex); - down_write(&l->mutex); - l->key.type = type; - l->key.ns = get_pid_ns(ns); - l->owner = cgrp; - list_add(&l->links, &cgrp->pidlists); - mutex_unlock(&cgrp->pidlist_mutex); - return l; -} - -/* - * Load a cgroup's pidarray with either procs' tgids or tasks' pids - */ -static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, - struct cgroup_pidlist **lp) -{ - pid_t *array; - int length; - int pid, n = 0; /* used for populating the array */ - struct cgroup_iter it; - struct task_struct *tsk; - struct cgroup_pidlist *l; - - /* - * If cgroup gets more users after we read count, we won't have - * enough space - tough. This race is indistinguishable to the - * caller from the case that the additional cgroup users didn't - * show up until sometime later on. - */ - length = cgroup_task_count(cgrp); - array = pidlist_allocate(length); - if (!array) - return -ENOMEM; - /* now, populate the array */ - cgroup_iter_start(cgrp, &it); - while ((tsk = cgroup_iter_next(cgrp, &it))) { - if (unlikely(n == length)) - break; - /* get tgid or pid for procs or tasks file respectively */ - if (type == CGROUP_FILE_PROCS) - pid = task_tgid_vnr(tsk); - else - pid = task_pid_vnr(tsk); - if (pid > 0) /* make sure to only use valid results */ - array[n++] = pid; - } - cgroup_iter_end(cgrp, &it); - length = n; - /* now sort & (if procs) strip out duplicates */ - sort(array, length, sizeof(pid_t), cmppid, NULL); - if (type == CGROUP_FILE_PROCS) - length = pidlist_uniq(array, length); - l = cgroup_pidlist_find(cgrp, type); - if (!l) { - pidlist_free(array); - return -ENOMEM; - } - /* store array, freeing old if necessary - lock already held */ - pidlist_free(l->list); - l->list = array; - l->length = length; - l->use_count++; - up_write(&l->mutex); - *lp = l; - return 0; -} - -/** - * cgroupstats_build - build and fill cgroupstats - * @stats: cgroupstats to fill information into - * @dentry: A dentry entry belonging to the cgroup for which stats have - * been requested. - * - * Build and fill cgroupstats so that taskstats can export it to user - * space. - */ -int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) -{ - int ret = -EINVAL; - struct cgroup *cgrp; - struct cgroup_iter it; - struct task_struct *tsk; - - /* - * Validate dentry by checking the superblock operations, - * and make sure it's a directory. - */ - if (dentry->d_sb->s_op != &cgroup_ops || - !S_ISDIR(dentry->d_inode->i_mode)) - goto err; - - ret = 0; - cgrp = dentry->d_fsdata; - - cgroup_iter_start(cgrp, &it); - while ((tsk = cgroup_iter_next(cgrp, &it))) { - switch (tsk->state) { - case TASK_RUNNING: - stats->nr_running++; - break; - case TASK_INTERRUPTIBLE: - stats->nr_sleeping++; - break; - case TASK_UNINTERRUPTIBLE: - stats->nr_uninterruptible++; - break; - case TASK_STOPPED: - stats->nr_stopped++; - break; - default: - if (delayacct_is_task_waiting_on_io(tsk)) - stats->nr_io_wait++; - break; - } - } - cgroup_iter_end(cgrp, &it); - -err: - return ret; -} - - -/* - * seq_file methods for the tasks/procs files. The seq_file position is the - * next pid to display; the seq_file iterator is a pointer to the pid - * in the cgroup->l->list array. - */ - -static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) -{ - /* - * Initially we receive a position value that corresponds to - * one more than the last pid shown (or 0 on the first call or - * after a seek to the start). Use a binary-search to find the - * next pid to display, if any - */ - struct cgroup_pidlist *l = s->private; - int index = 0, pid = *pos; - int *iter; - - down_read(&l->mutex); - if (pid) { - int end = l->length; - - while (index < end) { - int mid = (index + end) / 2; - if (l->list[mid] == pid) { - index = mid; - break; - } else if (l->list[mid] <= pid) - index = mid + 1; - else - end = mid; - } - } - /* If we're off the end of the array, we're done */ - if (index >= l->length) - return NULL; - /* Update the abstract position to be the actual pid that we found */ - iter = l->list + index; - *pos = *iter; - return iter; -} - -static void cgroup_pidlist_stop(struct seq_file *s, void *v) -{ - struct cgroup_pidlist *l = s->private; - up_read(&l->mutex); -} - -static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) -{ - struct cgroup_pidlist *l = s->private; - pid_t *p = v; - pid_t *end = l->list + l->length; - /* - * Advance to the next pid in the array. If this goes off the - * end, we're done - */ - p++; - if (p >= end) { - return NULL; - } else { - *pos = *p; - return p; - } -} - -static int cgroup_pidlist_show(struct seq_file *s, void *v) -{ - return seq_printf(s, "%d\n", *(int *)v); -} - -/* - * seq_operations functions for iterating on pidlists through seq_file - - * independent of whether it's tasks or procs - */ -static const struct seq_operations cgroup_pidlist_seq_operations = { - .start = cgroup_pidlist_start, - .stop = cgroup_pidlist_stop, - .next = cgroup_pidlist_next, - .show = cgroup_pidlist_show, -}; - -static void cgroup_release_pid_array(struct cgroup_pidlist *l) -{ - /* - * the case where we're the last user of this particular pidlist will - * have us remove it from the cgroup's list, which entails taking the - * mutex. since in pidlist_find the pidlist->lock depends on cgroup-> - * pidlist_mutex, we have to take pidlist_mutex first. - */ - mutex_lock(&l->owner->pidlist_mutex); - down_write(&l->mutex); - BUG_ON(!l->use_count); - if (!--l->use_count) { - /* we're the last user if refcount is 0; remove and free */ - list_del(&l->links); - mutex_unlock(&l->owner->pidlist_mutex); - pidlist_free(l->list); - put_pid_ns(l->key.ns); - up_write(&l->mutex); - kfree(l); - return; - } - mutex_unlock(&l->owner->pidlist_mutex); - up_write(&l->mutex); -} - -static int cgroup_pidlist_release(struct inode *inode, struct file *file) -{ - struct cgroup_pidlist *l; - if (!(file->f_mode & FMODE_READ)) - return 0; - /* - * the seq_file will only be initialized if the file was opened for - * reading; hence we check if it's not null only in that case. - */ - l = ((struct seq_file *)file->private_data)->private; - cgroup_release_pid_array(l); - return seq_release(inode, file); -} - -static const struct file_operations cgroup_pidlist_operations = { - .read = seq_read, - .llseek = seq_lseek, - .write = cgroup_file_write, - .release = cgroup_pidlist_release, -}; - -/* - * The following functions handle opens on a file that displays a pidlist - * (tasks or procs). Prepare an array of the process/thread IDs of whoever's - * in the cgroup. - */ -/* helper function for the two below it */ -static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type) -{ - struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); - struct cgroup_pidlist *l; - int retval; - - /* Nothing to do for write-only files */ - if (!(file->f_mode & FMODE_READ)) - return 0; - - /* have the array populated */ - retval = pidlist_array_load(cgrp, type, &l); - if (retval) - return retval; - /* configure file information */ - file->f_op = &cgroup_pidlist_operations; - - retval = seq_open(file, &cgroup_pidlist_seq_operations); - if (retval) { - cgroup_release_pid_array(l); - return retval; - } - ((struct seq_file *)file->private_data)->private = l; - return 0; -} -static int cgroup_tasks_open(struct inode *unused, struct file *file) -{ - return cgroup_pidlist_open(file, CGROUP_FILE_TASKS); -} -static int cgroup_procs_open(struct inode *unused, struct file *file) -{ - return cgroup_pidlist_open(file, CGROUP_FILE_PROCS); -} - -static u64 cgroup_read_notify_on_release(struct cgroup *cgrp, - struct cftype *cft) -{ - return notify_on_release(cgrp); -} - -static int cgroup_write_notify_on_release(struct cgroup *cgrp, - struct cftype *cft, - u64 val) -{ - clear_bit(CGRP_RELEASABLE, &cgrp->flags); - if (val) - set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); - else - clear_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); - return 0; -} - -/* - * When dput() is called asynchronously, if umount has been done and - * then deactivate_super() in cgroup_free_fn() kills the superblock, - * there's a small window that vfs will see the root dentry with non-zero - * refcnt and trigger BUG(). - * - * That's why we hold a reference before dput() and drop it right after. - */ -static void cgroup_dput(struct cgroup *cgrp) -{ - struct super_block *sb = cgrp->root->sb; - - atomic_inc(&sb->s_active); - dput(cgrp->dentry); - deactivate_super(sb); -} - -/* - * Unregister event and free resources. - * - * Gets called from workqueue. - */ -static void cgroup_event_remove(struct work_struct *work) -{ - struct cgroup_event *event = container_of(work, struct cgroup_event, - remove); - struct cgroup *cgrp = event->cgrp; - - remove_wait_queue(event->wqh, &event->wait); - - event->cft->unregister_event(cgrp, event->cft, event->eventfd); - - /* Notify userspace the event is going away. */ - eventfd_signal(event->eventfd, 1); - - eventfd_ctx_put(event->eventfd); - kfree(event); - cgroup_dput(cgrp); -} - -/* - * Gets called on POLLHUP on eventfd when user closes it. - * - * Called with wqh->lock held and interrupts disabled. - */ -static int cgroup_event_wake(wait_queue_t *wait, unsigned mode, - int sync, void *key) -{ - struct cgroup_event *event = container_of(wait, - struct cgroup_event, wait); - struct cgroup *cgrp = event->cgrp; - unsigned long flags = (unsigned long)key; - - if (flags & POLLHUP) { - /* - * If the event has been detached at cgroup removal, we - * can simply return knowing the other side will cleanup - * for us. - * - * We can't race against event freeing since the other - * side will require wqh->lock via remove_wait_queue(), - * which we hold. - */ - spin_lock(&cgrp->event_list_lock); - if (!list_empty(&event->list)) { - list_del_init(&event->list); - /* - * We are in atomic context, but cgroup_event_remove() - * may sleep, so we have to call it in workqueue. - */ - schedule_work(&event->remove); - } - spin_unlock(&cgrp->event_list_lock); - } - - return 0; -} - -static void cgroup_event_ptable_queue_proc(struct file *file, - wait_queue_head_t *wqh, poll_table *pt) -{ - struct cgroup_event *event = container_of(pt, - struct cgroup_event, pt); - - event->wqh = wqh; - add_wait_queue(wqh, &event->wait); -} - -/* - * Parse input and register new cgroup event handler. - * - * Input must be in format '<event_fd> <control_fd> <args>'. - * Interpretation of args is defined by control file implementation. - */ -static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft, - const char *buffer) -{ - struct cgroup_event *event = NULL; - struct cgroup *cgrp_cfile; - unsigned int efd, cfd; - struct file *efile = NULL; - struct file *cfile = NULL; - char *endp; - int ret; - - efd = simple_strtoul(buffer, &endp, 10); - if (*endp != ' ') - return -EINVAL; - buffer = endp + 1; - - cfd = simple_strtoul(buffer, &endp, 10); - if ((*endp != ' ') && (*endp != '\0')) - return -EINVAL; - buffer = endp + 1; - - event = kzalloc(sizeof(*event), GFP_KERNEL); - if (!event) - return -ENOMEM; - event->cgrp = cgrp; - INIT_LIST_HEAD(&event->list); - init_poll_funcptr(&event->pt, cgroup_event_ptable_queue_proc); - init_waitqueue_func_entry(&event->wait, cgroup_event_wake); - INIT_WORK(&event->remove, cgroup_event_remove); - - efile = eventfd_fget(efd); - if (IS_ERR(efile)) { - ret = PTR_ERR(efile); - goto fail; - } - - event->eventfd = eventfd_ctx_fileget(efile); - if (IS_ERR(event->eventfd)) { - ret = PTR_ERR(event->eventfd); - goto fail; - } - - cfile = fget(cfd); - if (!cfile) { - ret = -EBADF; - goto fail; - } - - /* the process need read permission on control file */ - /* AV: shouldn't we check that it's been opened for read instead? */ - ret = inode_permission(file_inode(cfile), MAY_READ); - if (ret < 0) - goto fail; - - event->cft = __file_cft(cfile); - if (IS_ERR(event->cft)) { - ret = PTR_ERR(event->cft); - goto fail; - } - - /* - * The file to be monitored must be in the same cgroup as - * cgroup.event_control is. - */ - cgrp_cfile = __d_cgrp(cfile->f_dentry->d_parent); - if (cgrp_cfile != cgrp) { - ret = -EINVAL; - goto fail; - } - - if (!event->cft->register_event || !event->cft->unregister_event) { - ret = -EINVAL; - goto fail; - } - - ret = event->cft->register_event(cgrp, event->cft, - event->eventfd, buffer); - if (ret) - goto fail; - - efile->f_op->poll(efile, &event->pt); - - /* - * Events should be removed after rmdir of cgroup directory, but before - * destroying subsystem state objects. Let's take reference to cgroup - * directory dentry to do that. - */ - dget(cgrp->dentry); - - spin_lock(&cgrp->event_list_lock); - list_add(&event->list, &cgrp->event_list); - spin_unlock(&cgrp->event_list_lock); - - fput(cfile); - fput(efile); - - return 0; - -fail: - if (cfile) - fput(cfile); - - if (event && event->eventfd && !IS_ERR(event->eventfd)) - eventfd_ctx_put(event->eventfd); - - if (!IS_ERR_OR_NULL(efile)) - fput(efile); - - kfree(event); - - return ret; -} - -static u64 cgroup_clone_children_read(struct cgroup *cgrp, - struct cftype *cft) -{ - return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); -} - -static int cgroup_clone_children_write(struct cgroup *cgrp, - struct cftype *cft, - u64 val) -{ - if (val) - set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); - else - clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); - return 0; -} - -static struct cftype cgroup_base_files[] = { - { - .name = "cgroup.procs", - .open = cgroup_procs_open, - .write_u64 = cgroup_procs_write, - .release = cgroup_pidlist_release, - .mode = S_IRUGO | S_IWUSR, - }, - { - .name = "cgroup.event_control", - .write_string = cgroup_write_event_control, - .mode = S_IWUGO, - }, - { - .name = "cgroup.clone_children", - .flags = CFTYPE_INSANE, - .read_u64 = cgroup_clone_children_read, - .write_u64 = cgroup_clone_children_write, - }, - { - .name = "cgroup.sane_behavior", - .flags = CFTYPE_ONLY_ON_ROOT, - .read_seq_string = cgroup_sane_behavior_show, - }, - - /* - * Historical crazy stuff. These don't have "cgroup." prefix and - * don't exist if sane_behavior. If you're depending on these, be - * prepared to be burned. - */ - { - .name = "tasks", - .flags = CFTYPE_INSANE, /* use "procs" instead */ - .open = cgroup_tasks_open, - .write_u64 = cgroup_tasks_write, - .release = cgroup_pidlist_release, - .mode = S_IRUGO | S_IWUSR, - }, - { - .name = "notify_on_release", - .flags = CFTYPE_INSANE, - .read_u64 = cgroup_read_notify_on_release, - .write_u64 = cgroup_write_notify_on_release, - }, - { - .name = "release_agent", - .flags = CFTYPE_INSANE | CFTYPE_ONLY_ON_ROOT, - .read_seq_string = cgroup_release_agent_show, - .write_string = cgroup_release_agent_write, - .max_write_len = PATH_MAX, - }, - { } /* terminate */ -}; - -/** - * cgroup_populate_dir - selectively creation of files in a directory - * @cgrp: target cgroup - * @base_files: true if the base files should be added - * @subsys_mask: mask of the subsystem ids whose files should be added - */ -static int cgroup_populate_dir(struct cgroup *cgrp, bool base_files, - unsigned long subsys_mask) -{ - int err; - struct cgroup_subsys *ss; - - if (base_files) { - err = cgroup_addrm_files(cgrp, NULL, cgroup_base_files, true); - if (err < 0) - return err; - } - - /* process cftsets of each subsystem */ - for_each_root_subsys(cgrp->root, ss) { - struct cftype_set *set; - if (!test_bit(ss->subsys_id, &subsys_mask)) - continue; - - list_for_each_entry(set, &ss->cftsets, node) - cgroup_addrm_files(cgrp, ss, set->cfts, true); - } - - /* This cgroup is ready now */ - for_each_root_subsys(cgrp->root, ss) { - struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; - struct css_id *id = rcu_dereference_protected(css->id, true); - - /* - * Update id->css pointer and make this css visible from - * CSS ID functions. This pointer will be dereferened - * from RCU-read-side without locks. - */ - if (id) - rcu_assign_pointer(id->css, css); - } - - return 0; -} - -static void css_dput_fn(struct work_struct *work) -{ - struct cgroup_subsys_state *css = - container_of(work, struct cgroup_subsys_state, dput_work); - - cgroup_dput(css->cgroup); -} - -static void css_release(struct percpu_ref *ref) -{ - struct cgroup_subsys_state *css = - container_of(ref, struct cgroup_subsys_state, refcnt); - - schedule_work(&css->dput_work); -} - -static void init_cgroup_css(struct cgroup_subsys_state *css, - struct cgroup_subsys *ss, - struct cgroup *cgrp) -{ - css->cgroup = cgrp; - css->flags = 0; - css->id = NULL; - if (cgrp == cgroup_dummy_top) - css->flags |= CSS_ROOT; - BUG_ON(cgrp->subsys[ss->subsys_id]); - cgrp->subsys[ss->subsys_id] = css; - - /* - * css holds an extra ref to @cgrp->dentry which is put on the last - * css_put(). dput() requires process context, which css_put() may - * be called without. @css->dput_work will be used to invoke - * dput() asynchronously from css_put(). - */ - INIT_WORK(&css->dput_work, css_dput_fn); -} - -/* invoke ->post_create() on a new CSS and mark it online if successful */ -static int online_css(struct cgroup_subsys *ss, struct cgroup *cgrp) -{ - int ret = 0; - - lockdep_assert_held(&cgroup_mutex); - - if (ss->css_online) - ret = ss->css_online(cgrp); - if (!ret) - cgrp->subsys[ss->subsys_id]->flags |= CSS_ONLINE; - return ret; -} - -/* if the CSS is online, invoke ->pre_destory() on it and mark it offline */ -static void offline_css(struct cgroup_subsys *ss, struct cgroup *cgrp) - __releases(&cgroup_mutex) __acquires(&cgroup_mutex) -{ - struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; - - lockdep_assert_held(&cgroup_mutex); - - if (!(css->flags & CSS_ONLINE)) - return; - - if (ss->css_offline) - ss->css_offline(cgrp); - - cgrp->subsys[ss->subsys_id]->flags &= ~CSS_ONLINE; -} - -/* - * cgroup_create - create a cgroup - * @parent: cgroup that will be parent of the new cgroup - * @dentry: dentry of the new cgroup - * @mode: mode to set on new inode - * - * Must be called with the mutex on the parent inode held - */ -static long cgroup_create(struct cgroup *parent, struct dentry *dentry, - umode_t mode) -{ - struct cgroup *cgrp; - struct cgroup_name *name; - struct cgroupfs_root *root = parent->root; - int err = 0; - struct cgroup_subsys *ss; - struct super_block *sb = root->sb; - - /* allocate the cgroup and its ID, 0 is reserved for the root */ - cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); - if (!cgrp) - return -ENOMEM; - - name = cgroup_alloc_name(dentry); - if (!name) - goto err_free_cgrp; - rcu_assign_pointer(cgrp->name, name); - - cgrp->id = ida_simple_get(&root->cgroup_ida, 1, 0, GFP_KERNEL); - if (cgrp->id < 0) - goto err_free_name; - - /* - * Only live parents can have children. Note that the liveliness - * check isn't strictly necessary because cgroup_mkdir() and - * cgroup_rmdir() are fully synchronized by i_mutex; however, do it - * anyway so that locking is contained inside cgroup proper and we - * don't get nasty surprises if we ever grow another caller. - */ - if (!cgroup_lock_live_group(parent)) { - err = -ENODEV; - goto err_free_id; - } - - /* Grab a reference on the superblock so the hierarchy doesn't - * get deleted on unmount if there are child cgroups. This - * can be done outside cgroup_mutex, since the sb can't - * disappear while someone has an open control file on the - * fs */ - atomic_inc(&sb->s_active); - - init_cgroup_housekeeping(cgrp); - - dentry->d_fsdata = cgrp; - cgrp->dentry = dentry; - - cgrp->parent = parent; - cgrp->root = parent->root; - - if (notify_on_release(parent)) - set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); - - if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags)) - set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); - - for_each_root_subsys(root, ss) { - struct cgroup_subsys_state *css; - - css = ss->css_alloc(cgrp); - if (IS_ERR(css)) { - err = PTR_ERR(css); - goto err_free_all; - } - - err = percpu_ref_init(&css->refcnt, css_release); - if (err) - goto err_free_all; - - init_cgroup_css(css, ss, cgrp); - - if (ss->use_id) { - err = alloc_css_id(ss, parent, cgrp); - if (err) - goto err_free_all; - } - } - - /* - * Create directory. cgroup_create_file() returns with the new - * directory locked on success so that it can be populated without - * dropping cgroup_mutex. - */ - err = cgroup_create_file(dentry, S_IFDIR | mode, sb); - if (err < 0) - goto err_free_all; - lockdep_assert_held(&dentry->d_inode->i_mutex); - - cgrp->serial_nr = cgroup_serial_nr_next++; - - /* allocation complete, commit to creation */ - list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children); - root->number_of_cgroups++; - - /* each css holds a ref to the cgroup's dentry */ - for_each_root_subsys(root, ss) - dget(dentry); - - /* hold a ref to the parent's dentry */ - dget(parent->dentry); - - /* creation succeeded, notify subsystems */ - for_each_root_subsys(root, ss) { - err = online_css(ss, cgrp); - if (err) - goto err_destroy; - - if (ss->broken_hierarchy && !ss->warned_broken_hierarchy && - parent->parent) { - pr_warning("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n", - current->comm, current->pid, ss->name); - if (!strcmp(ss->name, "memory")) - pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n"); - ss->warned_broken_hierarchy = true; - } - } - - err = cgroup_populate_dir(cgrp, true, root->subsys_mask); - if (err) - goto err_destroy; - - mutex_unlock(&cgroup_mutex); - mutex_unlock(&cgrp->dentry->d_inode->i_mutex); - - return 0; - -err_free_all: - for_each_root_subsys(root, ss) { - struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; - - if (css) { - percpu_ref_cancel_init(&css->refcnt); - ss->css_free(cgrp); - } - } - mutex_unlock(&cgroup_mutex); - /* Release the reference count that we took on the superblock */ - deactivate_super(sb); -err_free_id: - ida_simple_remove(&root->cgroup_ida, cgrp->id); -err_free_name: - kfree(rcu_dereference_raw(cgrp->name)); -err_free_cgrp: - kfree(cgrp); - return err; - -err_destroy: - cgroup_destroy_locked(cgrp); - mutex_unlock(&cgroup_mutex); - mutex_unlock(&dentry->d_inode->i_mutex); - return err; -} - -static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) -{ - struct cgroup *c_parent = dentry->d_parent->d_fsdata; - - /* the vfs holds inode->i_mutex already */ - return cgroup_create(c_parent, dentry, mode | S_IFDIR); -} - -static void cgroup_css_killed(struct cgroup *cgrp) -{ - if (!atomic_dec_and_test(&cgrp->css_kill_cnt)) - return; - - /* percpu ref's of all css's are killed, kick off the next step */ - INIT_WORK(&cgrp->destroy_work, cgroup_offline_fn); - schedule_work(&cgrp->destroy_work); -} - -static void css_ref_killed_fn(struct percpu_ref *ref) -{ - struct cgroup_subsys_state *css = - container_of(ref, struct cgroup_subsys_state, refcnt); - - cgroup_css_killed(css->cgroup); -} - -/** - * cgroup_destroy_locked - the first stage of cgroup destruction - * @cgrp: cgroup to be destroyed - * - * css's make use of percpu refcnts whose killing latency shouldn't be - * exposed to userland and are RCU protected. Also, cgroup core needs to - * guarantee that css_tryget() won't succeed by the time ->css_offline() is - * invoked. To satisfy all the requirements, destruction is implemented in - * the following two steps. - * - * s1. Verify @cgrp can be destroyed and mark it dying. Remove all - * userland visible parts and start killing the percpu refcnts of - * css's. Set up so that the next stage will be kicked off once all - * the percpu refcnts are confirmed to be killed. - * - * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the - * rest of destruction. Once all cgroup references are gone, the - * cgroup is RCU-freed. - * - * This function implements s1. After this step, @cgrp is gone as far as - * the userland is concerned and a new cgroup with the same name may be - * created. As cgroup doesn't care about the names internally, this - * doesn't cause any problem. - */ -static int cgroup_destroy_locked(struct cgroup *cgrp) - __releases(&cgroup_mutex) __acquires(&cgroup_mutex) -{ - struct dentry *d = cgrp->dentry; - struct cgroup_event *event, *tmp; - struct cgroup_subsys *ss; - bool empty; - - lockdep_assert_held(&d->d_inode->i_mutex); - lockdep_assert_held(&cgroup_mutex); - - /* - * css_set_lock synchronizes access to ->cset_links and prevents - * @cgrp from being removed while __put_css_set() is in progress. - */ - read_lock(&css_set_lock); - empty = list_empty(&cgrp->cset_links) && list_empty(&cgrp->children); - read_unlock(&css_set_lock); - if (!empty) - return -EBUSY; - - /* - * Block new css_tryget() by killing css refcnts. cgroup core - * guarantees that, by the time ->css_offline() is invoked, no new - * css reference will be given out via css_tryget(). We can't - * simply call percpu_ref_kill() and proceed to offlining css's - * because percpu_ref_kill() doesn't guarantee that the ref is seen - * as killed on all CPUs on return. - * - * Use percpu_ref_kill_and_confirm() to get notifications as each - * css is confirmed to be seen as killed on all CPUs. The - * notification callback keeps track of the number of css's to be - * killed and schedules cgroup_offline_fn() to perform the rest of - * destruction once the percpu refs of all css's are confirmed to - * be killed. - */ - atomic_set(&cgrp->css_kill_cnt, 1); - for_each_root_subsys(cgrp->root, ss) { - struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; - - /* - * Killing would put the base ref, but we need to keep it - * alive until after ->css_offline. - */ - percpu_ref_get(&css->refcnt); - - atomic_inc(&cgrp->css_kill_cnt); - percpu_ref_kill_and_confirm(&css->refcnt, css_ref_killed_fn); - } - cgroup_css_killed(cgrp); - - /* - * Mark @cgrp dead. This prevents further task migration and child - * creation by disabling cgroup_lock_live_group(). Note that - * CGRP_DEAD assertion is depended upon by cgroup_next_sibling() to - * resume iteration after dropping RCU read lock. See - * cgroup_next_sibling() for details. - */ - set_bit(CGRP_DEAD, &cgrp->flags); - - /* CGRP_DEAD is set, remove from ->release_list for the last time */ - raw_spin_lock(&release_list_lock); - if (!list_empty(&cgrp->release_list)) - list_del_init(&cgrp->release_list); - raw_spin_unlock(&release_list_lock); - - /* - * Remove @cgrp directory. The removal puts the base ref but we - * aren't quite done with @cgrp yet, so hold onto it. - */ - dget(d); - cgroup_d_remove_dir(d); - - /* - * Unregister events and notify userspace. - * Notify userspace about cgroup removing only after rmdir of cgroup - * directory to avoid race between userspace and kernelspace. - */ - spin_lock(&cgrp->event_list_lock); - list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) { - list_del_init(&event->list); - schedule_work(&event->remove); - } - spin_unlock(&cgrp->event_list_lock); - - return 0; -}; - -/** - * cgroup_offline_fn - the second step of cgroup destruction - * @work: cgroup->destroy_free_work - * - * This function is invoked from a work item for a cgroup which is being - * destroyed after the percpu refcnts of all css's are guaranteed to be - * seen as killed on all CPUs, and performs the rest of destruction. This - * is the second step of destruction described in the comment above - * cgroup_destroy_locked(). - */ -static void cgroup_offline_fn(struct work_struct *work) -{ - struct cgroup *cgrp = container_of(work, struct cgroup, destroy_work); - struct cgroup *parent = cgrp->parent; - struct dentry *d = cgrp->dentry; - struct cgroup_subsys *ss; - - mutex_lock(&cgroup_mutex); - - /* - * css_tryget() is guaranteed to fail now. Tell subsystems to - * initate destruction. - */ - for_each_root_subsys(cgrp->root, ss) - offline_css(ss, cgrp); - - /* - * Put the css refs from cgroup_destroy_locked(). Each css holds - * an extra reference to the cgroup's dentry and cgroup removal - * proceeds regardless of css refs. On the last put of each css, - * whenever that may be, the extra dentry ref is put so that dentry - * destruction happens only after all css's are released. - */ - for_each_root_subsys(cgrp->root, ss) - css_put(cgrp->subsys[ss->subsys_id]); - - /* delete this cgroup from parent->children */ - list_del_rcu(&cgrp->sibling); - - dput(d); - - set_bit(CGRP_RELEASABLE, &parent->flags); - check_for_release(parent); - - mutex_unlock(&cgroup_mutex); -} - -static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) -{ - int ret; - - mutex_lock(&cgroup_mutex); - ret = cgroup_destroy_locked(dentry->d_fsdata); - mutex_unlock(&cgroup_mutex); - - return ret; -} - -static void __init_or_module cgroup_init_cftsets(struct cgroup_subsys *ss) -{ - INIT_LIST_HEAD(&ss->cftsets); - - /* - * base_cftset is embedded in subsys itself, no need to worry about - * deregistration. - */ - if (ss->base_cftypes) { - ss->base_cftset.cfts = ss->base_cftypes; - list_add_tail(&ss->base_cftset.node, &ss->cftsets); - } -} - -static void __init cgroup_init_subsys(struct cgroup_subsys *ss) -{ - struct cgroup_subsys_state *css; - - printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); - - mutex_lock(&cgroup_mutex); - - /* init base cftset */ - cgroup_init_cftsets(ss); - - /* Create the top cgroup state for this subsystem */ - list_add(&ss->sibling, &cgroup_dummy_root.subsys_list); - ss->root = &cgroup_dummy_root; - css = ss->css_alloc(cgroup_dummy_top); - /* We don't handle early failures gracefully */ - BUG_ON(IS_ERR(css)); - init_cgroup_css(css, ss, cgroup_dummy_top); - - /* Update the init_css_set to contain a subsys - * pointer to this state - since the subsystem is - * newly registered, all tasks and hence the - * init_css_set is in the subsystem's top cgroup. */ - init_css_set.subsys[ss->subsys_id] = css; - - need_forkexit_callback |= ss->fork || ss->exit; - - /* At system boot, before all subsystems have been - * registered, no tasks have been forked, so we don't - * need to invoke fork callbacks here. */ - BUG_ON(!list_empty(&init_task.tasks)); - - BUG_ON(online_css(ss, cgroup_dummy_top)); - - mutex_unlock(&cgroup_mutex); - - /* this function shouldn't be used with modular subsystems, since they - * need to register a subsys_id, among other things */ - BUG_ON(ss->module); -} - -/** - * cgroup_load_subsys: load and register a modular subsystem at runtime - * @ss: the subsystem to load - * - * This function should be called in a modular subsystem's initcall. If the - * subsystem is built as a module, it will be assigned a new subsys_id and set - * up for use. If the subsystem is built-in anyway, work is delegated to the - * simpler cgroup_init_subsys. - */ -int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) -{ - struct cgroup_subsys_state *css; - int i, ret; - struct hlist_node *tmp; - struct css_set *cset; - unsigned long key; - - /* check name and function validity */ - if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN || - ss->css_alloc == NULL || ss->css_free == NULL) - return -EINVAL; - - /* - * we don't support callbacks in modular subsystems. this check is - * before the ss->module check for consistency; a subsystem that could - * be a module should still have no callbacks even if the user isn't - * compiling it as one. - */ - if (ss->fork || ss->exit) - return -EINVAL; - - /* - * an optionally modular subsystem is built-in: we want to do nothing, - * since cgroup_init_subsys will have already taken care of it. - */ - if (ss->module == NULL) { - /* a sanity check */ - BUG_ON(cgroup_subsys[ss->subsys_id] != ss); - return 0; - } - - /* init base cftset */ - cgroup_init_cftsets(ss); - - mutex_lock(&cgroup_mutex); - cgroup_subsys[ss->subsys_id] = ss; - - /* - * no ss->css_alloc seems to need anything important in the ss - * struct, so this can happen first (i.e. before the dummy root - * attachment). - */ - css = ss->css_alloc(cgroup_dummy_top); - if (IS_ERR(css)) { - /* failure case - need to deassign the cgroup_subsys[] slot. */ - cgroup_subsys[ss->subsys_id] = NULL; - mutex_unlock(&cgroup_mutex); - return PTR_ERR(css); - } - - list_add(&ss->sibling, &cgroup_dummy_root.subsys_list); - ss->root = &cgroup_dummy_root; - - /* our new subsystem will be attached to the dummy hierarchy. */ - init_cgroup_css(css, ss, cgroup_dummy_top); - /* init_idr must be after init_cgroup_css because it sets css->id. */ - if (ss->use_id) { - ret = cgroup_init_idr(ss, css); - if (ret) - goto err_unload; - } - - /* - * Now we need to entangle the css into the existing css_sets. unlike - * in cgroup_init_subsys, there are now multiple css_sets, so each one - * will need a new pointer to it; done by iterating the css_set_table. - * furthermore, modifying the existing css_sets will corrupt the hash - * table state, so each changed css_set will need its hash recomputed. - * this is all done under the css_set_lock. - */ - write_lock(&css_set_lock); - hash_for_each_safe(css_set_table, i, tmp, cset, hlist) { - /* skip entries that we already rehashed */ - if (cset->subsys[ss->subsys_id]) - continue; - /* remove existing entry */ - hash_del(&cset->hlist); - /* set new value */ - cset->subsys[ss->subsys_id] = css; - /* recompute hash and restore entry */ - key = css_set_hash(cset->subsys); - hash_add(css_set_table, &cset->hlist, key); - } - write_unlock(&css_set_lock); - - ret = online_css(ss, cgroup_dummy_top); - if (ret) - goto err_unload; - - /* success! */ - mutex_unlock(&cgroup_mutex); - return 0; - -err_unload: - mutex_unlock(&cgroup_mutex); - /* @ss can't be mounted here as try_module_get() would fail */ - cgroup_unload_subsys(ss); - return ret; -} -EXPORT_SYMBOL_GPL(cgroup_load_subsys); - -/** - * cgroup_unload_subsys: unload a modular subsystem - * @ss: the subsystem to unload - * - * This function should be called in a modular subsystem's exitcall. When this - * function is invoked, the refcount on the subsystem's module will be 0, so - * the subsystem will not be attached to any hierarchy. - */ -void cgroup_unload_subsys(struct cgroup_subsys *ss) -{ - struct cgrp_cset_link *link; - - BUG_ON(ss->module == NULL); - - /* - * we shouldn't be called if the subsystem is in use, and the use of - * try_module_get in parse_cgroupfs_options should ensure that it - * doesn't start being used while we're killing it off. - */ - BUG_ON(ss->root != &cgroup_dummy_root); - - mutex_lock(&cgroup_mutex); - - offline_css(ss, cgroup_dummy_top); - - if (ss->use_id) - idr_destroy(&ss->idr); - - /* deassign the subsys_id */ - cgroup_subsys[ss->subsys_id] = NULL; - - /* remove subsystem from the dummy root's list of subsystems */ - list_del_init(&ss->sibling); - - /* - * disentangle the css from all css_sets attached to the dummy - * top. as in loading, we need to pay our respects to the hashtable - * gods. - */ - write_lock(&css_set_lock); - list_for_each_entry(link, &cgroup_dummy_top->cset_links, cset_link) { - struct css_set *cset = link->cset; - unsigned long key; - - hash_del(&cset->hlist); - cset->subsys[ss->subsys_id] = NULL; - key = css_set_hash(cset->subsys); - hash_add(css_set_table, &cset->hlist, key); - } - write_unlock(&css_set_lock); - - /* - * remove subsystem's css from the cgroup_dummy_top and free it - - * need to free before marking as null because ss->css_free needs - * the cgrp->subsys pointer to find their state. note that this - * also takes care of freeing the css_id. - */ - ss->css_free(cgroup_dummy_top); - cgroup_dummy_top->subsys[ss->subsys_id] = NULL; - - mutex_unlock(&cgroup_mutex); -} -EXPORT_SYMBOL_GPL(cgroup_unload_subsys); - -/** - * cgroup_init_early - cgroup initialization at system boot - * - * Initialize cgroups at system boot, and initialize any - * subsystems that request early init. - */ -int __init cgroup_init_early(void) -{ - struct cgroup_subsys *ss; - int i; - - atomic_set(&init_css_set.refcount, 1); - INIT_LIST_HEAD(&init_css_set.cgrp_links); - INIT_LIST_HEAD(&init_css_set.tasks); - INIT_HLIST_NODE(&init_css_set.hlist); - css_set_count = 1; - init_cgroup_root(&cgroup_dummy_root); - cgroup_root_count = 1; - RCU_INIT_POINTER(init_task.cgroups, &init_css_set); - - init_cgrp_cset_link.cset = &init_css_set; - init_cgrp_cset_link.cgrp = cgroup_dummy_top; - list_add(&init_cgrp_cset_link.cset_link, &cgroup_dummy_top->cset_links); - list_add(&init_cgrp_cset_link.cgrp_link, &init_css_set.cgrp_links); - - /* at bootup time, we don't worry about modular subsystems */ - for_each_builtin_subsys(ss, i) { - BUG_ON(!ss->name); - BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN); - BUG_ON(!ss->css_alloc); - BUG_ON(!ss->css_free); - if (ss->subsys_id != i) { - printk(KERN_ERR "cgroup: Subsys %s id == %d\n", - ss->name, ss->subsys_id); - BUG(); - } - - if (ss->early_init) - cgroup_init_subsys(ss); - } - return 0; -} - -/** - * cgroup_init - cgroup initialization - * - * Register cgroup filesystem and /proc file, and initialize - * any subsystems that didn't request early init. - */ -int __init cgroup_init(void) -{ - struct cgroup_subsys *ss; - unsigned long key; - int i, err; - - err = bdi_init(&cgroup_backing_dev_info); - if (err) - return err; - - for_each_builtin_subsys(ss, i) { - if (!ss->early_init) - cgroup_init_subsys(ss); - if (ss->use_id) - cgroup_init_idr(ss, init_css_set.subsys[ss->subsys_id]); - } - - /* allocate id for the dummy hierarchy */ - mutex_lock(&cgroup_mutex); - mutex_lock(&cgroup_root_mutex); - - /* Add init_css_set to the hash table */ - key = css_set_hash(init_css_set.subsys); - hash_add(css_set_table, &init_css_set.hlist, key); - - BUG_ON(cgroup_init_root_id(&cgroup_dummy_root, 0, 1)); - - mutex_unlock(&cgroup_root_mutex); - mutex_unlock(&cgroup_mutex); - - cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj); - if (!cgroup_kobj) { - err = -ENOMEM; - goto out; - } - - err = register_filesystem(&cgroup_fs_type); - if (err < 0) { - kobject_put(cgroup_kobj); - goto out; - } - - proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations); - -out: - if (err) - bdi_destroy(&cgroup_backing_dev_info); - - return err; -} - -/* - * proc_cgroup_show() - * - Print task's cgroup paths into seq_file, one line for each hierarchy - * - Used for /proc/<pid>/cgroup. - * - No need to task_lock(tsk) on this tsk->cgroup reference, as it - * doesn't really matter if tsk->cgroup changes after we read it, - * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it - * anyway. No need to check that tsk->cgroup != NULL, thanks to - * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks - * cgroup to top_cgroup. - */ - -/* TODO: Use a proper seq_file iterator */ -int proc_cgroup_show(struct seq_file *m, void *v) -{ - struct pid *pid; - struct task_struct *tsk; - char *buf; - int retval; - struct cgroupfs_root *root; - - retval = -ENOMEM; - buf = kmalloc(PAGE_SIZE, GFP_KERNEL); - if (!buf) - goto out; - - retval = -ESRCH; - pid = m->private; - tsk = get_pid_task(pid, PIDTYPE_PID); - if (!tsk) - goto out_free; - - retval = 0; - - mutex_lock(&cgroup_mutex); - - for_each_active_root(root) { - struct cgroup_subsys *ss; - struct cgroup *cgrp; - int count = 0; - - seq_printf(m, "%d:", root->hierarchy_id); - for_each_root_subsys(root, ss) - seq_printf(m, "%s%s", count++ ? "," : "", ss->name); - if (strlen(root->name)) - seq_printf(m, "%sname=%s", count ? "," : "", - root->name); - seq_putc(m, ':'); - cgrp = task_cgroup_from_root(tsk, root); - retval = cgroup_path(cgrp, buf, PAGE_SIZE); - if (retval < 0) - goto out_unlock; - seq_puts(m, buf); - seq_putc(m, '\n'); - } - -out_unlock: - mutex_unlock(&cgroup_mutex); - put_task_struct(tsk); -out_free: - kfree(buf); -out: - return retval; -} - -/* Display information about each subsystem and each hierarchy */ -static int proc_cgroupstats_show(struct seq_file *m, void *v) -{ - struct cgroup_subsys *ss; - int i; - - seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); - /* - * ideally we don't want subsystems moving around while we do this. - * cgroup_mutex is also necessary to guarantee an atomic snapshot of - * subsys/hierarchy state. - */ - mutex_lock(&cgroup_mutex); - - for_each_subsys(ss, i) - seq_printf(m, "%s\t%d\t%d\t%d\n", - ss->name, ss->root->hierarchy_id, - ss->root->number_of_cgroups, !ss->disabled); - - mutex_unlock(&cgroup_mutex); - return 0; -} - -static int cgroupstats_open(struct inode *inode, struct file *file) -{ - return single_open(file, proc_cgroupstats_show, NULL); -} - -static const struct file_operations proc_cgroupstats_operations = { - .open = cgroupstats_open, - .read = seq_read, - .llseek = seq_lseek, - .release = single_release, -}; - -/** - * cgroup_fork - attach newly forked task to its parents cgroup. - * @child: pointer to task_struct of forking parent process. - * - * Description: A task inherits its parent's cgroup at fork(). - * - * A pointer to the shared css_set was automatically copied in - * fork.c by dup_task_struct(). However, we ignore that copy, since - * it was not made under the protection of RCU or cgroup_mutex, so - * might no longer be a valid cgroup pointer. cgroup_attach_task() might - * have already changed current->cgroups, allowing the previously - * referenced cgroup group to be removed and freed. - * - * At the point that cgroup_fork() is called, 'current' is the parent - * task, and the passed argument 'child' points to the child task. - */ -void cgroup_fork(struct task_struct *child) -{ - task_lock(current); - get_css_set(task_css_set(current)); - child->cgroups = current->cgroups; - task_unlock(current); - INIT_LIST_HEAD(&child->cg_list); -} - -/** - * cgroup_post_fork - called on a new task after adding it to the task list - * @child: the task in question - * - * Adds the task to the list running through its css_set if necessary and - * call the subsystem fork() callbacks. Has to be after the task is - * visible on the task list in case we race with the first call to - * cgroup_iter_start() - to guarantee that the new task ends up on its - * list. - */ -void cgroup_post_fork(struct task_struct *child) -{ - struct cgroup_subsys *ss; - int i; - - /* - * use_task_css_set_links is set to 1 before we walk the tasklist - * under the tasklist_lock and we read it here after we added the child - * to the tasklist under the tasklist_lock as well. If the child wasn't - * yet in the tasklist when we walked through it from - * cgroup_enable_task_cg_lists(), then use_task_css_set_links value - * should be visible now due to the paired locking and barriers implied - * by LOCK/UNLOCK: it is written before the tasklist_lock unlock - * in cgroup_enable_task_cg_lists() and read here after the tasklist_lock - * lock on fork. - */ - if (use_task_css_set_links) { - write_lock(&css_set_lock); - task_lock(child); - if (list_empty(&child->cg_list)) - list_add(&child->cg_list, &task_css_set(child)->tasks); - task_unlock(child); - write_unlock(&css_set_lock); - } - - /* - * Call ss->fork(). This must happen after @child is linked on - * css_set; otherwise, @child might change state between ->fork() - * and addition to css_set. - */ - if (need_forkexit_callback) { - /* - * fork/exit callbacks are supported only for builtin - * subsystems, and the builtin section of the subsys - * array is immutable, so we don't need to lock the - * subsys array here. On the other hand, modular section - * of the array can be freed at module unload, so we - * can't touch that. - */ - for_each_builtin_subsys(ss, i) - if (ss->fork) - ss->fork(child); - } -} - -/** - * cgroup_exit - detach cgroup from exiting task - * @tsk: pointer to task_struct of exiting process - * @run_callback: run exit callbacks? - * - * Description: Detach cgroup from @tsk and release it. - * - * Note that cgroups marked notify_on_release force every task in - * them to take the global cgroup_mutex mutex when exiting. - * This could impact scaling on very large systems. Be reluctant to - * use notify_on_release cgroups where very high task exit scaling - * is required on large systems. - * - * the_top_cgroup_hack: - * - * Set the exiting tasks cgroup to the root cgroup (top_cgroup). - * - * We call cgroup_exit() while the task is still competent to - * handle notify_on_release(), then leave the task attached to the - * root cgroup in each hierarchy for the remainder of its exit. - * - * To do this properly, we would increment the reference count on - * top_cgroup, and near the very end of the kernel/exit.c do_exit() - * code we would add a second cgroup function call, to drop that - * reference. This would just create an unnecessary hot spot on - * the top_cgroup reference count, to no avail. - * - * Normally, holding a reference to a cgroup without bumping its - * count is unsafe. The cgroup could go away, or someone could - * attach us to a different cgroup, decrementing the count on - * the first cgroup that we never incremented. But in this case, - * top_cgroup isn't going away, and either task has PF_EXITING set, - * which wards off any cgroup_attach_task() attempts, or task is a failed - * fork, never visible to cgroup_attach_task. - */ -void cgroup_exit(struct task_struct *tsk, int run_callbacks) -{ - struct cgroup_subsys *ss; - struct css_set *cset; - int i; - - /* - * Unlink from the css_set task list if necessary. - * Optimistically check cg_list before taking - * css_set_lock - */ - if (!list_empty(&tsk->cg_list)) { - write_lock(&css_set_lock); - if (!list_empty(&tsk->cg_list)) - list_del_init(&tsk->cg_list); - write_unlock(&css_set_lock); - } - - /* Reassign the task to the init_css_set. */ - task_lock(tsk); - cset = task_css_set(tsk); - RCU_INIT_POINTER(tsk->cgroups, &init_css_set); - - if (run_callbacks && need_forkexit_callback) { - /* - * fork/exit callbacks are supported only for builtin - * subsystems, see cgroup_post_fork() for details. - */ - for_each_builtin_subsys(ss, i) { - if (ss->exit) { - struct cgroup *old_cgrp = cset->subsys[i]->cgroup; - struct cgroup *cgrp = task_cgroup(tsk, i); - - ss->exit(cgrp, old_cgrp, tsk); - } - } - } - task_unlock(tsk); - - put_css_set_taskexit(cset); -} - -static void check_for_release(struct cgroup *cgrp) -{ - if (cgroup_is_releasable(cgrp) && - list_empty(&cgrp->cset_links) && list_empty(&cgrp->children)) { - /* - * Control Group is currently removeable. If it's not - * already queued for a userspace notification, queue - * it now - */ - int need_schedule_work = 0; - - raw_spin_lock(&release_list_lock); - if (!cgroup_is_dead(cgrp) && - list_empty(&cgrp->release_list)) { - list_add(&cgrp->release_list, &release_list); - need_schedule_work = 1; - } - raw_spin_unlock(&release_list_lock); - if (need_schedule_work) - schedule_work(&release_agent_work); - } -} - -/* - * Notify userspace when a cgroup is released, by running the - * configured release agent with the name of the cgroup (path - * relative to the root of cgroup file system) as the argument. - * - * Most likely, this user command will try to rmdir this cgroup. - * - * This races with the possibility that some other task will be - * attached to this cgroup before it is removed, or that some other - * user task will 'mkdir' a child cgroup of this cgroup. That's ok. - * The presumed 'rmdir' will fail quietly if this cgroup is no longer - * unused, and this cgroup will be reprieved from its death sentence, - * to continue to serve a useful existence. Next time it's released, - * we will get notified again, if it still has 'notify_on_release' set. - * - * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which - * means only wait until the task is successfully execve()'d. The - * separate release agent task is forked by call_usermodehelper(), - * then control in this thread returns here, without waiting for the - * release agent task. We don't bother to wait because the caller of - * this routine has no use for the exit status of the release agent - * task, so no sense holding our caller up for that. - */ -static void cgroup_release_agent(struct work_struct *work) -{ - BUG_ON(work != &release_agent_work); - mutex_lock(&cgroup_mutex); - raw_spin_lock(&release_list_lock); - while (!list_empty(&release_list)) { - char *argv[3], *envp[3]; - int i; - char *pathbuf = NULL, *agentbuf = NULL; - struct cgroup *cgrp = list_entry(release_list.next, - struct cgroup, - release_list); - list_del_init(&cgrp->release_list); - raw_spin_unlock(&release_list_lock); - pathbuf = kmalloc(PAGE_SIZE, GFP_KERNEL); - if (!pathbuf) - goto continue_free; - if (cgroup_path(cgrp, pathbuf, PAGE_SIZE) < 0) - goto continue_free; - agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); - if (!agentbuf) - goto continue_free; - - i = 0; - argv[i++] = agentbuf; - argv[i++] = pathbuf; - argv[i] = NULL; - - i = 0; - /* minimal command environment */ - envp[i++] = "HOME=/"; - envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; - envp[i] = NULL; - - /* Drop the lock while we invoke the usermode helper, - * since the exec could involve hitting disk and hence - * be a slow process */ - mutex_unlock(&cgroup_mutex); - call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); - mutex_lock(&cgroup_mutex); - continue_free: - kfree(pathbuf); - kfree(agentbuf); - raw_spin_lock(&release_list_lock); - } - raw_spin_unlock(&release_list_lock); - mutex_unlock(&cgroup_mutex); -} - -static int __init cgroup_disable(char *str) -{ - struct cgroup_subsys *ss; - char *token; - int i; - - while ((token = strsep(&str, ",")) != NULL) { - if (!*token) - continue; - - /* - * cgroup_disable, being at boot time, can't know about - * module subsystems, so we don't worry about them. - */ - for_each_builtin_subsys(ss, 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); - -/* - * Functons for CSS ID. - */ - -/* to get ID other than 0, this should be called when !cgroup_is_dead() */ -unsigned short css_id(struct cgroup_subsys_state *css) -{ - struct css_id *cssid; - - /* - * This css_id() can return correct value when somone has refcnt - * on this or this is under rcu_read_lock(). Once css->id is allocated, - * it's unchanged until freed. - */ - cssid = rcu_dereference_raw(css->id); - - if (cssid) - return cssid->id; - return 0; -} -EXPORT_SYMBOL_GPL(css_id); - -/** - * css_is_ancestor - test "root" css is an ancestor of "child" - * @child: the css to be tested. - * @root: the css supporsed to be an ancestor of the child. - * - * Returns true if "root" is an ancestor of "child" in its hierarchy. Because - * this function reads css->id, the caller must hold rcu_read_lock(). - * But, considering usual usage, the csses should be valid objects after test. - * Assuming that the caller will do some action to the child if this returns - * returns true, the caller must take "child";s reference count. - * If "child" is valid object and this returns true, "root" is valid, too. - */ - -bool css_is_ancestor(struct cgroup_subsys_state *child, - const struct cgroup_subsys_state *root) -{ - struct css_id *child_id; - struct css_id *root_id; - - child_id = rcu_dereference(child->id); - if (!child_id) - return false; - root_id = rcu_dereference(root->id); - if (!root_id) - return false; - if (child_id->depth < root_id->depth) - return false; - if (child_id->stack[root_id->depth] != root_id->id) - return false; - return true; -} - -void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css) -{ - struct css_id *id = rcu_dereference_protected(css->id, true); - - /* When this is called before css_id initialization, id can be NULL */ - if (!id) - return; - - BUG_ON(!ss->use_id); - - rcu_assign_pointer(id->css, NULL); - rcu_assign_pointer(css->id, NULL); - spin_lock(&ss->id_lock); - idr_remove(&ss->idr, id->id); - spin_unlock(&ss->id_lock); - kfree_rcu(id, rcu_head); -} -EXPORT_SYMBOL_GPL(free_css_id); - -/* - * This is called by init or create(). Then, calls to this function are - * always serialized (By cgroup_mutex() at create()). - */ - -static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth) -{ - struct css_id *newid; - int ret, size; - - BUG_ON(!ss->use_id); - - size = sizeof(*newid) + sizeof(unsigned short) * (depth + 1); - newid = kzalloc(size, GFP_KERNEL); - if (!newid) - return ERR_PTR(-ENOMEM); - - idr_preload(GFP_KERNEL); - spin_lock(&ss->id_lock); - /* Don't use 0. allocates an ID of 1-65535 */ - ret = idr_alloc(&ss->idr, newid, 1, CSS_ID_MAX + 1, GFP_NOWAIT); - spin_unlock(&ss->id_lock); - idr_preload_end(); - - /* Returns error when there are no free spaces for new ID.*/ - if (ret < 0) - goto err_out; - - newid->id = ret; - newid->depth = depth; - return newid; -err_out: - kfree(newid); - return ERR_PTR(ret); - -} - -static int __init_or_module cgroup_init_idr(struct cgroup_subsys *ss, - struct cgroup_subsys_state *rootcss) -{ - struct css_id *newid; - - spin_lock_init(&ss->id_lock); - idr_init(&ss->idr); - - newid = get_new_cssid(ss, 0); - if (IS_ERR(newid)) - return PTR_ERR(newid); - - newid->stack[0] = newid->id; - RCU_INIT_POINTER(newid->css, rootcss); - RCU_INIT_POINTER(rootcss->id, newid); - return 0; -} - -static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent, - struct cgroup *child) -{ - int subsys_id, i, depth = 0; - struct cgroup_subsys_state *parent_css, *child_css; - struct css_id *child_id, *parent_id; - - subsys_id = ss->subsys_id; - parent_css = parent->subsys[subsys_id]; - child_css = child->subsys[subsys_id]; - parent_id = rcu_dereference_protected(parent_css->id, true); - depth = parent_id->depth + 1; - - child_id = get_new_cssid(ss, depth); - if (IS_ERR(child_id)) - return PTR_ERR(child_id); - - for (i = 0; i < depth; i++) - child_id->stack[i] = parent_id->stack[i]; - child_id->stack[depth] = child_id->id; - /* - * child_id->css pointer will be set after this cgroup is available - * see cgroup_populate_dir() - */ - rcu_assign_pointer(child_css->id, child_id); - - return 0; -} - -/** - * css_lookup - lookup css by id - * @ss: cgroup subsys to be looked into. - * @id: the id - * - * Returns pointer to cgroup_subsys_state if there is valid one with id. - * NULL if not. Should be called under rcu_read_lock() - */ -struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id) -{ - struct css_id *cssid = NULL; - - BUG_ON(!ss->use_id); - cssid = idr_find(&ss->idr, id); - - if (unlikely(!cssid)) - return NULL; - - return rcu_dereference(cssid->css); -} -EXPORT_SYMBOL_GPL(css_lookup); - -/* - * get corresponding css from file open on cgroupfs directory - */ -struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id) -{ - struct cgroup *cgrp; - struct inode *inode; - struct cgroup_subsys_state *css; - - inode = file_inode(f); - /* check in cgroup filesystem dir */ - if (inode->i_op != &cgroup_dir_inode_operations) - return ERR_PTR(-EBADF); - - if (id < 0 || id >= CGROUP_SUBSYS_COUNT) - return ERR_PTR(-EINVAL); - - /* get cgroup */ - cgrp = __d_cgrp(f->f_dentry); - css = cgrp->subsys[id]; - return css ? css : ERR_PTR(-ENOENT); -} - -#ifdef CONFIG_CGROUP_DEBUG -static struct cgroup_subsys_state *debug_css_alloc(struct cgroup *cgrp) -{ - struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); - - if (!css) - return ERR_PTR(-ENOMEM); - - return css; -} - -static void debug_css_free(struct cgroup *cgrp) -{ - kfree(cgrp->subsys[debug_subsys_id]); -} - -static u64 debug_taskcount_read(struct cgroup *cgrp, struct cftype *cft) -{ - return cgroup_task_count(cgrp); -} - -static u64 current_css_set_read(struct cgroup *cgrp, struct cftype *cft) -{ - return (u64)(unsigned long)current->cgroups; -} - -static u64 current_css_set_refcount_read(struct cgroup *cgrp, - struct cftype *cft) -{ - u64 count; - - rcu_read_lock(); - count = atomic_read(&task_css_set(current)->refcount); - rcu_read_unlock(); - return count; -} - -static int current_css_set_cg_links_read(struct cgroup *cgrp, - struct cftype *cft, - struct seq_file *seq) -{ - struct cgrp_cset_link *link; - struct css_set *cset; - - read_lock(&css_set_lock); - rcu_read_lock(); - cset = rcu_dereference(current->cgroups); - list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { - struct cgroup *c = link->cgrp; - const char *name; - - if (c->dentry) - name = c->dentry->d_name.name; - else - name = "?"; - seq_printf(seq, "Root %d group %s\n", - c->root->hierarchy_id, name); - } - rcu_read_unlock(); - read_unlock(&css_set_lock); - return 0; -} - -#define MAX_TASKS_SHOWN_PER_CSS 25 -static int cgroup_css_links_read(struct cgroup *cgrp, - struct cftype *cft, - struct seq_file *seq) -{ - struct cgrp_cset_link *link; - - read_lock(&css_set_lock); - list_for_each_entry(link, &cgrp->cset_links, cset_link) { - struct css_set *cset = link->cset; - struct task_struct *task; - int count = 0; - seq_printf(seq, "css_set %p\n", cset); - list_for_each_entry(task, &cset->tasks, cg_list) { - if (count++ > MAX_TASKS_SHOWN_PER_CSS) { - seq_puts(seq, " ...\n"); - break; - } else { - seq_printf(seq, " task %d\n", - task_pid_vnr(task)); - } - } - } - read_unlock(&css_set_lock); - return 0; -} - -static u64 releasable_read(struct cgroup *cgrp, struct cftype *cft) -{ - return test_bit(CGRP_RELEASABLE, &cgrp->flags); -} - -static struct cftype debug_files[] = { - { - .name = "taskcount", - .read_u64 = debug_taskcount_read, - }, - - { - .name = "current_css_set", - .read_u64 = current_css_set_read, - }, - - { - .name = "current_css_set_refcount", - .read_u64 = current_css_set_refcount_read, - }, - - { - .name = "current_css_set_cg_links", - .read_seq_string = current_css_set_cg_links_read, - }, - - { - .name = "cgroup_css_links", - .read_seq_string = cgroup_css_links_read, - }, - - { - .name = "releasable", - .read_u64 = releasable_read, - }, - - { } /* terminate */ -}; - -struct cgroup_subsys debug_subsys = { - .name = "debug", - .css_alloc = debug_css_alloc, - .css_free = debug_css_free, - .subsys_id = debug_subsys_id, - .base_cftypes = debug_files, -}; -#endif /* CONFIG_CGROUP_DEBUG */ |