diff options
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 1085 |
1 files changed, 605 insertions, 480 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 79818507e444..f34c41bfaa37 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -88,11 +88,12 @@ static DEFINE_MUTEX(cgroup_root_mutex); /* * Generate an array of cgroup subsystem pointers. At boot time, this is - * populated up to CGROUP_BUILTIN_SUBSYS_COUNT, and modular subsystems are + * 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, +#define SUBSYS(_x) [_x ## _subsys_id] = &_x ## _subsys, +#define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option) static struct cgroup_subsys *subsys[CGROUP_SUBSYS_COUNT] = { #include <linux/cgroup_subsys.h> }; @@ -111,13 +112,13 @@ struct cgroupfs_root { * The bitmask of subsystems intended to be attached to this * hierarchy */ - unsigned long subsys_bits; + unsigned long subsys_mask; /* Unique id for this hierarchy. */ int hierarchy_id; /* The bitmask of subsystems currently attached to this hierarchy */ - unsigned long actual_subsys_bits; + unsigned long actual_subsys_mask; /* A list running through the attached subsystems */ struct list_head subsys_list; @@ -137,6 +138,9 @@ struct cgroupfs_root { /* Hierarchy-specific flags */ unsigned long flags; + /* IDs for cgroups in this hierarchy */ + struct ida cgroup_ida; + /* The path to use for release notifications. */ char release_agent_path[PATH_MAX]; @@ -170,8 +174,8 @@ 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_is_removed() - * css_tryget() should be used for avoiding race. + * is called after synchronize_rcu(). But for safe use, css_tryget() + * should be used for avoiding race. */ struct cgroup_subsys_state __rcu *css; /* @@ -241,6 +245,10 @@ static DEFINE_SPINLOCK(hierarchy_id_lock); */ static int need_forkexit_callback __read_mostly; +static int cgroup_destroy_locked(struct cgroup *cgrp); +static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys, + struct cftype cfts[], bool is_add); + #ifdef CONFIG_PROVE_LOCKING int cgroup_lock_is_held(void) { @@ -276,7 +284,8 @@ inline int cgroup_is_removed(const struct cgroup *cgrp) /* bits in struct cgroupfs_root flags field */ enum { - ROOT_NOPREFIX, /* mounted subsystems have no named prefix */ + ROOT_NOPREFIX, /* mounted subsystems have no named prefix */ + ROOT_XATTR, /* supports extended attributes */ }; static int cgroup_is_releasable(const struct cgroup *cgrp) @@ -292,11 +301,6 @@ static int notify_on_release(const struct cgroup *cgrp) return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); } -static int clone_children(const struct cgroup *cgrp) -{ - return test_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); -} - /* * for_each_subsys() allows you to iterate on each subsystem attached to * an active hierarchy @@ -556,7 +560,7 @@ static struct css_set *find_existing_css_set( * won't change, so no need for locking. */ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { - if (root->subsys_bits & (1UL << i)) { + if (root->subsys_mask & (1UL << i)) { /* Subsystem is in this hierarchy. So we want * the subsystem state from the new * cgroup */ @@ -780,12 +784,12 @@ static struct cgroup *task_cgroup_from_root(struct task_struct *task, * The task_lock() exception * * The need for this exception arises from the action of - * cgroup_attach_task(), which overwrites one tasks cgroup pointer with + * 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'ss cgroup pointer we use + * 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. * @@ -824,7 +828,8 @@ EXPORT_SYMBOL_GPL(cgroup_unlock); static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode); static struct dentry *cgroup_lookup(struct inode *, struct dentry *, unsigned int); static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry); -static int cgroup_populate_dir(struct cgroup *cgrp); +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; @@ -851,30 +856,6 @@ static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb) return inode; } -/* - * Call subsys's pre_destroy handler. - * This is called before css refcnt check. - */ -static int cgroup_call_pre_destroy(struct cgroup *cgrp) -{ - struct cgroup_subsys *ss; - int ret = 0; - - for_each_subsys(cgrp->root, ss) { - if (!ss->pre_destroy) - continue; - - ret = ss->pre_destroy(cgrp); - if (ret) { - /* ->pre_destroy() failure is being deprecated */ - WARN_ON_ONCE(!ss->__DEPRECATED_clear_css_refs); - break; - } - } - - return ret; -} - static void cgroup_diput(struct dentry *dentry, struct inode *inode) { /* is dentry a directory ? if so, kfree() associated cgroup */ @@ -895,7 +876,7 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode) * Release the subsystem state objects. */ for_each_subsys(cgrp->root, ss) - ss->destroy(cgrp); + ss->css_free(cgrp); cgrp->root->number_of_cgroups--; mutex_unlock(&cgroup_mutex); @@ -912,15 +893,20 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode) */ BUG_ON(!list_empty(&cgrp->pidlists)); + simple_xattrs_free(&cgrp->xattrs); + + ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id); kfree_rcu(cgrp, rcu_head); } else { struct cfent *cfe = __d_cfe(dentry); struct cgroup *cgrp = dentry->d_parent->d_fsdata; + struct cftype *cft = cfe->type; WARN_ONCE(!list_empty(&cfe->node) && cgrp != &cgrp->root->top_cgroup, "cfe still linked for %s\n", cfe->type->name); kfree(cfe); + simple_xattrs_free(&cft->xattrs); } iput(inode); } @@ -963,12 +949,29 @@ static int cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) return -ENOENT; } -static void cgroup_clear_directory(struct dentry *dir) +/** + * 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; - while (!list_empty(&cgrp->files)) - cgroup_rm_file(cgrp, NULL); + for_each_subsys(cgrp->root, ss) { + struct cftype_set *set; + if (!test_bit(ss->subsys_id, &subsys_mask)) + continue; + list_for_each_entry(set, &ss->cftsets, node) + cgroup_addrm_files(cgrp, NULL, set->cfts, false); + } + if (base_files) { + while (!list_empty(&cgrp->files)) + cgroup_rm_file(cgrp, NULL); + } } /* @@ -977,8 +980,9 @@ static void cgroup_clear_directory(struct dentry *dir) 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); + cgroup_clear_directory(dentry, true, root->subsys_mask); parent = dentry->d_parent; spin_lock(&parent->d_lock); @@ -990,54 +994,27 @@ static void cgroup_d_remove_dir(struct dentry *dentry) } /* - * A queue for waiters to do rmdir() cgroup. A tasks will sleep when - * cgroup->count == 0 && list_empty(&cgroup->children) && subsys has some - * reference to css->refcnt. In general, this refcnt is expected to goes down - * to zero, soon. - * - * CGRP_WAIT_ON_RMDIR flag is set under cgroup's inode->i_mutex; - */ -static DECLARE_WAIT_QUEUE_HEAD(cgroup_rmdir_waitq); - -static void cgroup_wakeup_rmdir_waiter(struct cgroup *cgrp) -{ - if (unlikely(test_and_clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags))) - wake_up_all(&cgroup_rmdir_waitq); -} - -void cgroup_exclude_rmdir(struct cgroup_subsys_state *css) -{ - css_get(css); -} - -void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state *css) -{ - cgroup_wakeup_rmdir_waiter(css->cgroup); - css_put(css); -} - -/* * Call with cgroup_mutex held. Drops reference counts on modules, including * any duplicate ones that parse_cgroupfs_options took. If this function * returns an error, no reference counts are touched. */ static int rebind_subsystems(struct cgroupfs_root *root, - unsigned long final_bits) + unsigned long final_subsys_mask) { - unsigned long added_bits, removed_bits; + unsigned long added_mask, removed_mask; struct cgroup *cgrp = &root->top_cgroup; int i; BUG_ON(!mutex_is_locked(&cgroup_mutex)); BUG_ON(!mutex_is_locked(&cgroup_root_mutex)); - removed_bits = root->actual_subsys_bits & ~final_bits; - added_bits = final_bits & ~root->actual_subsys_bits; + removed_mask = root->actual_subsys_mask & ~final_subsys_mask; + added_mask = final_subsys_mask & ~root->actual_subsys_mask; /* Check that any added subsystems are currently free */ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { unsigned long bit = 1UL << i; struct cgroup_subsys *ss = subsys[i]; - if (!(bit & added_bits)) + if (!(bit & added_mask)) continue; /* * Nobody should tell us to do a subsys that doesn't exist: @@ -1062,7 +1039,7 @@ static int rebind_subsystems(struct cgroupfs_root *root, for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { struct cgroup_subsys *ss = subsys[i]; unsigned long bit = 1UL << i; - if (bit & added_bits) { + if (bit & added_mask) { /* We're binding this subsystem to this hierarchy */ BUG_ON(ss == NULL); BUG_ON(cgrp->subsys[i]); @@ -1075,7 +1052,7 @@ static int rebind_subsystems(struct cgroupfs_root *root, if (ss->bind) ss->bind(cgrp); /* refcount was already taken, and we're keeping it */ - } else if (bit & removed_bits) { + } else if (bit & removed_mask) { /* We're removing this subsystem */ BUG_ON(ss == NULL); BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]); @@ -1088,7 +1065,7 @@ static int rebind_subsystems(struct cgroupfs_root *root, list_move(&ss->sibling, &rootnode.subsys_list); /* subsystem is now free - drop reference on module */ module_put(ss->module); - } else if (bit & final_bits) { + } else if (bit & final_subsys_mask) { /* Subsystem state should already exist */ BUG_ON(ss == NULL); BUG_ON(!cgrp->subsys[i]); @@ -1105,7 +1082,7 @@ static int rebind_subsystems(struct cgroupfs_root *root, BUG_ON(cgrp->subsys[i]); } } - root->subsys_bits = root->actual_subsys_bits = final_bits; + root->subsys_mask = root->actual_subsys_mask = final_subsys_mask; synchronize_rcu(); return 0; @@ -1121,9 +1098,11 @@ static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry) seq_printf(seq, ",%s", ss->name); if (test_bit(ROOT_NOPREFIX, &root->flags)) seq_puts(seq, ",noprefix"); + if (test_bit(ROOT_XATTR, &root->flags)) + seq_puts(seq, ",xattr"); if (strlen(root->release_agent_path)) seq_printf(seq, ",release_agent=%s", root->release_agent_path); - if (clone_children(&root->top_cgroup)) + 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); @@ -1132,10 +1111,10 @@ static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry) } struct cgroup_sb_opts { - unsigned long subsys_bits; + unsigned long subsys_mask; unsigned long flags; char *release_agent; - bool clone_children; + bool cpuset_clone_children; char *name; /* User explicitly requested empty subsystem */ bool none; @@ -1186,7 +1165,11 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) continue; } if (!strcmp(token, "clone_children")) { - opts->clone_children = true; + opts->cpuset_clone_children = true; + continue; + } + if (!strcmp(token, "xattr")) { + set_bit(ROOT_XATTR, &opts->flags); continue; } if (!strncmp(token, "release_agent=", 14)) { @@ -1237,7 +1220,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) /* Mutually exclusive option 'all' + subsystem name */ if (all_ss) return -EINVAL; - set_bit(i, &opts->subsys_bits); + set_bit(i, &opts->subsys_mask); one_ss = true; break; @@ -1258,7 +1241,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) continue; if (ss->disabled) continue; - set_bit(i, &opts->subsys_bits); + set_bit(i, &opts->subsys_mask); } } @@ -1270,19 +1253,19 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) * the cpuset subsystem. */ if (test_bit(ROOT_NOPREFIX, &opts->flags) && - (opts->subsys_bits & mask)) + (opts->subsys_mask & mask)) return -EINVAL; /* Can't specify "none" and some subsystems */ - if (opts->subsys_bits && opts->none) + 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_bits && !opts->name) + if (!opts->subsys_mask && !opts->name) return -EINVAL; /* @@ -1291,10 +1274,10 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) * take duplicate reference counts on a subsystem that's already used, * but rebind_subsystems handles this case. */ - for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) { + for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { unsigned long bit = 1UL << i; - if (!(bit & opts->subsys_bits)) + if (!(bit & opts->subsys_mask)) continue; if (!try_module_get(subsys[i]->module)) { module_pin_failed = true; @@ -1307,11 +1290,11 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) * raced with a module_delete call, and to the user this is * essentially a "subsystem doesn't exist" case. */ - for (i--; i >= CGROUP_BUILTIN_SUBSYS_COUNT; i--) { + for (i--; i >= 0; i--) { /* drop refcounts only on the ones we took */ unsigned long bit = 1UL << i; - if (!(bit & opts->subsys_bits)) + if (!(bit & opts->subsys_mask)) continue; module_put(subsys[i]->module); } @@ -1321,13 +1304,13 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) return 0; } -static void drop_parsed_module_refcounts(unsigned long subsys_bits) +static void drop_parsed_module_refcounts(unsigned long subsys_mask) { int i; - for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) { + for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { unsigned long bit = 1UL << i; - if (!(bit & subsys_bits)) + if (!(bit & subsys_mask)) continue; module_put(subsys[i]->module); } @@ -1339,6 +1322,7 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data) struct cgroupfs_root *root = sb->s_fs_info; struct cgroup *cgrp = &root->top_cgroup; struct cgroup_sb_opts opts; + unsigned long added_mask, removed_mask; mutex_lock(&cgrp->dentry->d_inode->i_mutex); mutex_lock(&cgroup_mutex); @@ -1350,27 +1334,38 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data) goto out_unlock; /* See feature-removal-schedule.txt */ - if (opts.subsys_bits != root->actual_subsys_bits || opts.release_agent) + if (opts.subsys_mask != root->actual_subsys_mask || opts.release_agent) pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n", task_tgid_nr(current), current->comm); + added_mask = opts.subsys_mask & ~root->subsys_mask; + removed_mask = root->subsys_mask & ~opts.subsys_mask; + /* Don't allow flags or name to change at remount */ if (opts.flags != root->flags || (opts.name && strcmp(opts.name, root->name))) { ret = -EINVAL; - drop_parsed_module_refcounts(opts.subsys_bits); + drop_parsed_module_refcounts(opts.subsys_mask); goto out_unlock; } - ret = rebind_subsystems(root, opts.subsys_bits); + /* + * Clear out the files of subsystems that should be removed, do + * this before rebind_subsystems, since rebind_subsystems may + * change this hierarchy's subsys_list. + */ + cgroup_clear_directory(cgrp->dentry, false, removed_mask); + + ret = rebind_subsystems(root, opts.subsys_mask); if (ret) { - drop_parsed_module_refcounts(opts.subsys_bits); + /* rebind_subsystems failed, re-populate the removed files */ + cgroup_populate_dir(cgrp, false, removed_mask); + drop_parsed_module_refcounts(opts.subsys_mask); goto out_unlock; } - /* clear out any existing files and repopulate subsystem files */ - cgroup_clear_directory(cgrp->dentry); - cgroup_populate_dir(cgrp); + /* re-populate subsystem files */ + cgroup_populate_dir(cgrp, false, added_mask); if (opts.release_agent) strcpy(root->release_agent_path, opts.release_agent); @@ -1396,11 +1391,13 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp) INIT_LIST_HEAD(&cgrp->children); INIT_LIST_HEAD(&cgrp->files); INIT_LIST_HEAD(&cgrp->css_sets); + INIT_LIST_HEAD(&cgrp->allcg_node); INIT_LIST_HEAD(&cgrp->release_list); INIT_LIST_HEAD(&cgrp->pidlists); 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) @@ -1413,8 +1410,8 @@ static void init_cgroup_root(struct cgroupfs_root *root) root->number_of_cgroups = 1; cgrp->root = root; cgrp->top_cgroup = cgrp; - list_add_tail(&cgrp->allcg_node, &root->allcg_list); init_cgroup_housekeeping(cgrp); + list_add_tail(&cgrp->allcg_node, &root->allcg_list); } static bool init_root_id(struct cgroupfs_root *root) @@ -1455,8 +1452,8 @@ static int cgroup_test_super(struct super_block *sb, void *data) * If we asked for subsystems (or explicitly for no * subsystems) then they must match */ - if ((opts->subsys_bits || opts->none) - && (opts->subsys_bits != root->subsys_bits)) + if ((opts->subsys_mask || opts->none) + && (opts->subsys_mask != root->subsys_mask)) return 0; return 1; @@ -1466,7 +1463,7 @@ static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) { struct cgroupfs_root *root; - if (!opts->subsys_bits && !opts->none) + if (!opts->subsys_mask && !opts->none) return NULL; root = kzalloc(sizeof(*root), GFP_KERNEL); @@ -1479,14 +1476,15 @@ static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) } init_cgroup_root(root); - root->subsys_bits = opts->subsys_bits; + 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->clone_children) - set_bit(CGRP_CLONE_CHILDREN, &root->top_cgroup.flags); + if (opts->cpuset_clone_children) + set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->top_cgroup.flags); return root; } @@ -1499,6 +1497,7 @@ static void cgroup_drop_root(struct cgroupfs_root *root) spin_lock(&hierarchy_id_lock); ida_remove(&hierarchy_ida, root->hierarchy_id); spin_unlock(&hierarchy_id_lock); + ida_destroy(&root->cgroup_ida); kfree(root); } @@ -1511,7 +1510,7 @@ static int cgroup_set_super(struct super_block *sb, void *data) if (!opts->new_root) return -EINVAL; - BUG_ON(!opts->subsys_bits && !opts->none); + BUG_ON(!opts->subsys_mask && !opts->none); ret = set_anon_super(sb, NULL); if (ret) @@ -1629,7 +1628,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, if (ret) goto unlock_drop; - ret = rebind_subsystems(root, root->subsys_bits); + ret = rebind_subsystems(root, root->subsys_mask); if (ret == -EBUSY) { free_cg_links(&tmp_cg_links); goto unlock_drop; @@ -1664,12 +1663,11 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, free_cg_links(&tmp_cg_links); - BUG_ON(!list_empty(&root_cgrp->sibling)); BUG_ON(!list_empty(&root_cgrp->children)); BUG_ON(root->number_of_cgroups != 1); cred = override_creds(&init_cred); - cgroup_populate_dir(root_cgrp); + cgroup_populate_dir(root_cgrp, true, root->subsys_mask); revert_creds(cred); mutex_unlock(&cgroup_root_mutex); mutex_unlock(&cgroup_mutex); @@ -1681,7 +1679,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, */ cgroup_drop_root(opts.new_root); /* no subsys rebinding, so refcounts don't change */ - drop_parsed_module_refcounts(opts.subsys_bits); + drop_parsed_module_refcounts(opts.subsys_mask); } kfree(opts.release_agent); @@ -1695,7 +1693,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, drop_new_super: deactivate_locked_super(sb); drop_modules: - drop_parsed_module_refcounts(opts.subsys_bits); + drop_parsed_module_refcounts(opts.subsys_mask); out_err: kfree(opts.release_agent); kfree(opts.name); @@ -1713,7 +1711,6 @@ static void cgroup_kill_sb(struct super_block *sb) { BUG_ON(root->number_of_cgroups != 1); BUG_ON(!list_empty(&cgrp->children)); - BUG_ON(!list_empty(&cgrp->sibling)); mutex_lock(&cgroup_mutex); mutex_lock(&cgroup_root_mutex); @@ -1745,6 +1742,8 @@ static void cgroup_kill_sb(struct super_block *sb) { mutex_unlock(&cgroup_root_mutex); mutex_unlock(&cgroup_mutex); + simple_xattrs_free(&cgrp->xattrs); + kill_litter_super(sb); cgroup_drop_root(root); } @@ -1769,9 +1768,11 @@ static struct kobject *cgroup_kobj; */ int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) { + struct dentry *dentry = cgrp->dentry; char *start; - struct dentry *dentry = rcu_dereference_check(cgrp->dentry, - cgroup_lock_is_held()); + + rcu_lockdep_assert(rcu_read_lock_held() || cgroup_lock_is_held(), + "cgroup_path() called without proper locking"); if (!dentry || cgrp == dummytop) { /* @@ -1782,9 +1783,9 @@ int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) return 0; } - start = buf + buflen; + start = buf + buflen - 1; - *--start = '\0'; + *start = '\0'; for (;;) { int len = dentry->d_name.len; @@ -1795,8 +1796,7 @@ int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) if (!cgrp) break; - dentry = rcu_dereference_check(cgrp->dentry, - cgroup_lock_is_held()); + dentry = cgrp->dentry; if (!cgrp->parent) continue; if (--start < buf) @@ -1891,9 +1891,7 @@ EXPORT_SYMBOL_GPL(cgroup_taskset_size); /* * cgroup_task_migrate - move a task from one cgroup to another. * - * 'guarantee' is set if the caller promises that a new css_set for the task - * will already exist. If not set, this function might sleep, and can fail with - * -ENOMEM. Must be called with cgroup_mutex and threadgroup locked. + * Must be called with cgroup_mutex and threadgroup locked. */ static void cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp, struct task_struct *tsk, struct css_set *newcg) @@ -1923,9 +1921,8 @@ static void cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp, * trading it for newcg is protected by cgroup_mutex, we're safe to drop * it here; it will be freed under RCU. */ - put_css_set(oldcg); - set_bit(CGRP_RELEASABLE, &oldcgrp->flags); + put_css_set(oldcg); } /** @@ -1987,12 +1984,6 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) } synchronize_rcu(); - - /* - * wake up rmdir() waiter. the rmdir should fail since the cgroup - * is no longer empty. - */ - cgroup_wakeup_rmdir_waiter(cgrp); out: if (retval) { for_each_subsys(root, ss) { @@ -2162,7 +2153,6 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) * step 5: success! and cleanup */ synchronize_rcu(); - cgroup_wakeup_rmdir_waiter(cgrp); retval = 0; out_put_css_set_refs: if (retval) { @@ -2551,6 +2541,64 @@ static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry, return simple_rename(old_dir, old_dentry, new_dir, new_dentry); } +static struct simple_xattrs *__d_xattrs(struct dentry *dentry) +{ + if (S_ISDIR(dentry->d_inode->i_mode)) + return &__d_cgrp(dentry)->xattrs; + else + return &__d_cft(dentry)->xattrs; +} + +static inline int xattr_enabled(struct dentry *dentry) +{ + struct cgroupfs_root *root = dentry->d_sb->s_fs_info; + return test_bit(ROOT_XATTR, &root->flags); +} + +static bool is_valid_xattr(const char *name) +{ + if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) || + !strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) + return true; + return false; +} + +static int cgroup_setxattr(struct dentry *dentry, const char *name, + const void *val, size_t size, int flags) +{ + if (!xattr_enabled(dentry)) + return -EOPNOTSUPP; + if (!is_valid_xattr(name)) + return -EINVAL; + return simple_xattr_set(__d_xattrs(dentry), name, val, size, flags); +} + +static int cgroup_removexattr(struct dentry *dentry, const char *name) +{ + if (!xattr_enabled(dentry)) + return -EOPNOTSUPP; + if (!is_valid_xattr(name)) + return -EINVAL; + return simple_xattr_remove(__d_xattrs(dentry), name); +} + +static ssize_t cgroup_getxattr(struct dentry *dentry, const char *name, + void *buf, size_t size) +{ + if (!xattr_enabled(dentry)) + return -EOPNOTSUPP; + if (!is_valid_xattr(name)) + return -EINVAL; + return simple_xattr_get(__d_xattrs(dentry), name, buf, size); +} + +static ssize_t cgroup_listxattr(struct dentry *dentry, char *buf, size_t size) +{ + if (!xattr_enabled(dentry)) + return -EOPNOTSUPP; + return simple_xattr_list(__d_xattrs(dentry), buf, size); +} + static const struct file_operations cgroup_file_operations = { .read = cgroup_file_read, .write = cgroup_file_write, @@ -2559,11 +2607,22 @@ static const struct file_operations cgroup_file_operations = { .release = cgroup_file_release, }; +static const struct inode_operations cgroup_file_inode_operations = { + .setxattr = cgroup_setxattr, + .getxattr = cgroup_getxattr, + .listxattr = cgroup_listxattr, + .removexattr = cgroup_removexattr, +}; + static const struct inode_operations cgroup_dir_inode_operations = { .lookup = cgroup_lookup, .mkdir = cgroup_mkdir, .rmdir = cgroup_rmdir, .rename = cgroup_rename, + .setxattr = cgroup_setxattr, + .getxattr = cgroup_getxattr, + .listxattr = cgroup_listxattr, + .removexattr = cgroup_removexattr, }; static struct dentry *cgroup_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) @@ -2604,45 +2663,27 @@ static int cgroup_create_file(struct dentry *dentry, umode_t mode, /* start off with i_nlink == 2 (for "." entry) */ inc_nlink(inode); + inc_nlink(dentry->d_parent->d_inode); - /* start with the directory inode held, so that we can - * populate it without racing with another mkdir */ - mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD); + /* + * 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_create_dir - create a directory for an object. - * @cgrp: the cgroup we create the directory for. It must have a valid - * ->parent field. And we are going to fill its ->dentry field. - * @dentry: dentry of the new cgroup - * @mode: mode to set on new directory. - */ -static int cgroup_create_dir(struct cgroup *cgrp, struct dentry *dentry, - umode_t mode) -{ - struct dentry *parent; - int error = 0; - - parent = cgrp->parent->dentry; - error = cgroup_create_file(dentry, S_IFDIR | mode, cgrp->root->sb); - if (!error) { - dentry->d_fsdata = cgrp; - inc_nlink(parent->d_inode); - rcu_assign_pointer(cgrp->dentry, dentry); - dget(dentry); - } - dput(dentry); - - return error; -} - /** * cgroup_file_mode - deduce file mode of a control file * @cft: the control file in question @@ -2671,7 +2712,7 @@ static umode_t cgroup_file_mode(const struct cftype *cft) } static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys, - const struct cftype *cft) + struct cftype *cft) { struct dentry *dir = cgrp->dentry; struct cgroup *parent = __d_cgrp(dir); @@ -2681,11 +2722,7 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys, umode_t mode; char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 }; - /* does @cft->flags tell us to skip creation on @cgrp? */ - if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent) - return 0; - if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent) - return 0; + simple_xattrs_init(&cft->xattrs); if (subsys && !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) { strcpy(name, subsys->name); @@ -2721,12 +2758,18 @@ out: } static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys, - const struct cftype cfts[], bool is_add) + struct cftype cfts[], bool is_add) { - const struct cftype *cft; + struct cftype *cft; int err, ret = 0; for (cft = cfts; cft->name[0] != '\0'; cft++) { + /* does cft->flags tell us to skip this file on @cgrp? */ + if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent) + continue; + if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent) + continue; + if (is_add) err = cgroup_add_file(cgrp, subsys, cft); else @@ -2757,7 +2800,7 @@ static void cgroup_cfts_prepare(void) } static void cgroup_cfts_commit(struct cgroup_subsys *ss, - const struct cftype *cfts, bool is_add) + struct cftype *cfts, bool is_add) __releases(&cgroup_mutex) __releases(&cgroup_cft_mutex) { LIST_HEAD(pending); @@ -2808,7 +2851,7 @@ static void cgroup_cfts_commit(struct cgroup_subsys *ss, * 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, const struct cftype *cfts) +int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) { struct cftype_set *set; @@ -2838,7 +2881,7 @@ EXPORT_SYMBOL_GPL(cgroup_add_cftypes); * Returns 0 on successful unregistration, -ENOENT if @cfts is not * registered with @ss. */ -int cgroup_rm_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts) +int cgroup_rm_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) { struct cftype_set *set; @@ -2934,6 +2977,92 @@ static void cgroup_enable_task_cg_lists(void) write_unlock(&css_set_lock); } +/** + * cgroup_next_descendant_pre - find the next descendant for pre-order walk + * @pos: the current position (%NULL to initiate traversal) + * @cgroup: cgroup whose descendants to walk + * + * To be used by cgroup_for_each_descendant_pre(). Find the next + * descendant to visit for pre-order traversal of @cgroup's descendants. + */ +struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos, + struct cgroup *cgroup) +{ + struct cgroup *next; + + WARN_ON_ONCE(!rcu_read_lock_held()); + + /* if first iteration, pretend we just visited @cgroup */ + if (!pos) { + if (list_empty(&cgroup->children)) + return NULL; + pos = cgroup; + } + + /* visit the first child if exists */ + next = list_first_or_null_rcu(&pos->children, struct cgroup, sibling); + if (next) + return next; + + /* no child, visit my or the closest ancestor's next sibling */ + do { + next = list_entry_rcu(pos->sibling.next, struct cgroup, + sibling); + if (&next->sibling != &pos->parent->children) + return next; + + pos = pos->parent; + } while (pos != cgroup); + + return NULL; +} +EXPORT_SYMBOL_GPL(cgroup_next_descendant_pre); + +static struct cgroup *cgroup_leftmost_descendant(struct cgroup *pos) +{ + struct cgroup *last; + + do { + last = pos; + pos = list_first_or_null_rcu(&pos->children, struct cgroup, + sibling); + } while (pos); + + return last; +} + +/** + * cgroup_next_descendant_post - find the next descendant for post-order walk + * @pos: the current position (%NULL to initiate traversal) + * @cgroup: cgroup whose descendants to walk + * + * To be used by cgroup_for_each_descendant_post(). Find the next + * descendant to visit for post-order traversal of @cgroup's descendants. + */ +struct cgroup *cgroup_next_descendant_post(struct cgroup *pos, + struct cgroup *cgroup) +{ + struct cgroup *next; + + WARN_ON_ONCE(!rcu_read_lock_held()); + + /* if first iteration, visit the leftmost descendant */ + if (!pos) { + next = cgroup_leftmost_descendant(cgroup); + return next != cgroup ? next : NULL; + } + + /* if there's an unvisited sibling, visit its leftmost descendant */ + next = list_entry_rcu(pos->sibling.next, struct cgroup, sibling); + if (&next->sibling != &pos->parent->children) + return cgroup_leftmost_descendant(next); + + /* no sibling left, visit parent */ + next = pos->parent; + return next != cgroup ? next : NULL; +} +EXPORT_SYMBOL_GPL(cgroup_next_descendant_post); + void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it) __acquires(css_set_lock) { @@ -3647,7 +3776,7 @@ static int cgroup_event_wake(wait_queue_t *wait, unsigned mode, if (flags & POLLHUP) { __remove_wait_queue(event->wqh, &event->wait); spin_lock(&cgrp->event_list_lock); - list_del(&event->list); + list_del_init(&event->list); spin_unlock(&cgrp->event_list_lock); /* * We are in atomic context, but cgroup_event_remove() may @@ -3784,7 +3913,7 @@ fail: static u64 cgroup_clone_children_read(struct cgroup *cgrp, struct cftype *cft) { - return clone_children(cgrp); + return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); } static int cgroup_clone_children_write(struct cgroup *cgrp, @@ -3792,9 +3921,9 @@ static int cgroup_clone_children_write(struct cgroup *cgrp, u64 val) { if (val) - set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); + set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); else - clear_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); + clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); return 0; } @@ -3843,18 +3972,29 @@ static struct cftype files[] = { { } /* terminate */ }; -static int cgroup_populate_dir(struct cgroup *cgrp) +/** + * 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; - err = cgroup_addrm_files(cgrp, NULL, files, true); - if (err < 0) - return err; + if (base_files) { + err = cgroup_addrm_files(cgrp, NULL, files, true); + if (err < 0) + return err; + } /* process cftsets of each subsystem */ for_each_subsys(cgrp->root, ss) { struct cftype_set *set; + if (!test_bit(ss->subsys_id, &subsys_mask)) + continue; list_for_each_entry(set, &ss->cftsets, node) cgroup_addrm_files(cgrp, ss, set->cfts, true); @@ -3896,19 +4036,57 @@ static void init_cgroup_css(struct cgroup_subsys_state *css, css->flags = 0; css->id = NULL; if (cgrp == dummytop) - set_bit(CSS_ROOT, &css->flags); + css->flags |= CSS_ROOT; BUG_ON(cgrp->subsys[ss->subsys_id]); cgrp->subsys[ss->subsys_id] = css; /* - * If !clear_css_refs, 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(). + * 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); - if (ss->__DEPRECATED_clear_css_refs) - set_bit(CSS_CLEAR_CSS_REFS, &css->flags); +} + +/* invoke ->post_create() on a new CSS and mark it online if successful */ +static int online_css(struct cgroup_subsys *ss, struct cgroup *cgrp) +{ + int ret = 0; + + lockdep_assert_held(&cgroup_mutex); + + if (ss->css_online) + ret = ss->css_online(cgrp); + if (!ret) + cgrp->subsys[ss->subsys_id]->flags |= CSS_ONLINE; + return ret; +} + +/* if the CSS is online, invoke ->pre_destory() on it and mark it offline */ +static void offline_css(struct cgroup_subsys *ss, struct cgroup *cgrp) + __releases(&cgroup_mutex) __acquires(&cgroup_mutex) +{ + struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; + + lockdep_assert_held(&cgroup_mutex); + + if (!(css->flags & CSS_ONLINE)) + return; + + /* + * css_offline() should be called with cgroup_mutex unlocked. See + * 3fa59dfbc3 ("cgroup: fix potential deadlock in pre_destroy") for + * details. This temporary unlocking should go away once + * cgroup_mutex is unexported from controllers. + */ + if (ss->css_offline) { + mutex_unlock(&cgroup_mutex); + ss->css_offline(cgrp); + mutex_lock(&cgroup_mutex); + } + + cgrp->subsys[ss->subsys_id]->flags &= ~CSS_ONLINE; } /* @@ -3928,10 +4106,27 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, struct cgroup_subsys *ss; struct super_block *sb = root->sb; + /* allocate the cgroup and its ID, 0 is reserved for the root */ cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); if (!cgrp) return -ENOMEM; + cgrp->id = ida_simple_get(&root->cgroup_ida, 1, 0, GFP_KERNEL); + if (cgrp->id < 0) + goto err_free_cgrp; + + /* + * Only live parents can have children. Note that the liveliness + * check isn't strictly necessary because cgroup_mkdir() and + * cgroup_rmdir() are fully synchronized by i_mutex; however, do it + * anyway so that locking is contained inside cgroup proper and we + * don't get nasty surprises if we ever grow another caller. + */ + if (!cgroup_lock_live_group(parent)) { + err = -ENODEV; + goto err_free_id; + } + /* Grab a reference on the superblock so the hierarchy doesn't * get deleted on unmount if there are child cgroups. This * can be done outside cgroup_mutex, since the sb can't @@ -3939,8 +4134,6 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, * fs */ atomic_inc(&sb->s_active); - mutex_lock(&cgroup_mutex); - init_cgroup_housekeeping(cgrp); cgrp->parent = parent; @@ -3950,71 +4143,90 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, if (notify_on_release(parent)) set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); - if (clone_children(parent)) - set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags); + if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags)) + set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); for_each_subsys(root, ss) { - struct cgroup_subsys_state *css = ss->create(cgrp); + struct cgroup_subsys_state *css; + css = ss->css_alloc(cgrp); if (IS_ERR(css)) { err = PTR_ERR(css); - goto err_destroy; + 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_destroy; + goto err_free_all; } - /* At error, ->destroy() callback has to free assigned ID. */ - if (clone_children(parent) && ss->post_clone) - ss->post_clone(cgrp); } - list_add(&cgrp->sibling, &cgrp->parent->children); - root->number_of_cgroups++; - - err = cgroup_create_dir(cgrp, dentry, mode); + /* + * 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_remove; + goto err_free_all; + lockdep_assert_held(&dentry->d_inode->i_mutex); + + /* allocation complete, commit to creation */ + dentry->d_fsdata = cgrp; + cgrp->dentry = dentry; + list_add_tail(&cgrp->allcg_node, &root->allcg_list); + list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children); + root->number_of_cgroups++; - /* If !clear_css_refs, each css holds a ref to the cgroup's dentry */ + /* each css holds a ref to the cgroup's dentry */ for_each_subsys(root, ss) - if (!ss->__DEPRECATED_clear_css_refs) - dget(dentry); + dget(dentry); - /* The cgroup directory was pre-locked for us */ - BUG_ON(!mutex_is_locked(&cgrp->dentry->d_inode->i_mutex)); + /* creation succeeded, notify subsystems */ + for_each_subsys(root, ss) { + err = online_css(ss, cgrp); + if (err) + goto err_destroy; - list_add_tail(&cgrp->allcg_node, &root->allcg_list); + 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); - /* If err < 0, we have a half-filled directory - oh well ;) */ + 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_remove: - - list_del(&cgrp->sibling); - root->number_of_cgroups--; - - err_destroy: - +err_free_all: for_each_subsys(root, ss) { if (cgrp->subsys[ss->subsys_id]) - ss->destroy(cgrp); + ss->css_free(cgrp); } - mutex_unlock(&cgroup_mutex); - /* Release the reference count that we took on the superblock */ deactivate_super(sb); - +err_free_id: + ida_simple_remove(&root->cgroup_ida, cgrp->id); +err_free_cgrp: kfree(cgrp); return err; + +err_destroy: + cgroup_destroy_locked(cgrp); + mutex_unlock(&cgroup_mutex); + mutex_unlock(&dentry->d_inode->i_mutex); + return err; } static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) @@ -4066,153 +4278,60 @@ static int cgroup_has_css_refs(struct cgroup *cgrp) return 0; } -/* - * Atomically mark all (or else none) of the cgroup's CSS objects as - * CSS_REMOVED. Return true on success, or false if the cgroup has - * busy subsystems. Call with cgroup_mutex held - * - * Depending on whether a subsys has __DEPRECATED_clear_css_refs set or - * not, cgroup removal behaves differently. - * - * If clear is set, css refcnt for the subsystem should be zero before - * cgroup removal can be committed. This is implemented by - * CGRP_WAIT_ON_RMDIR and retry logic around ->pre_destroy(), which may be - * called multiple times until all css refcnts reach zero and is allowed to - * veto removal on any invocation. This behavior is deprecated and will be - * removed as soon as the existing user (memcg) is updated. - * - * If clear is not set, each css holds an extra reference to the cgroup's - * dentry and cgroup removal proceeds regardless of css refs. - * ->pre_destroy() will be called at least once and is not allowed to fail. - * 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. - */ -static int cgroup_clear_css_refs(struct cgroup *cgrp) +static int cgroup_destroy_locked(struct cgroup *cgrp) + __releases(&cgroup_mutex) __acquires(&cgroup_mutex) { + struct dentry *d = cgrp->dentry; + struct cgroup *parent = cgrp->parent; + DEFINE_WAIT(wait); + struct cgroup_event *event, *tmp; struct cgroup_subsys *ss; - unsigned long flags; - bool failed = false; + LIST_HEAD(tmp_list); + + lockdep_assert_held(&d->d_inode->i_mutex); + lockdep_assert_held(&cgroup_mutex); - local_irq_save(flags); + if (atomic_read(&cgrp->count) || !list_empty(&cgrp->children)) + return -EBUSY; /* - * Block new css_tryget() by deactivating refcnt. If all refcnts - * for subsystems w/ clear_css_refs set were 1 at the moment of - * deactivation, we succeeded. + * Block new css_tryget() by deactivating refcnt and mark @cgrp + * removed. This makes future css_tryget() and child creation + * attempts fail thus maintaining the removal conditions verified + * above. */ for_each_subsys(cgrp->root, ss) { struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; WARN_ON(atomic_read(&css->refcnt) < 0); atomic_add(CSS_DEACT_BIAS, &css->refcnt); - - if (ss->__DEPRECATED_clear_css_refs) - failed |= css_refcnt(css) != 1; } + set_bit(CGRP_REMOVED, &cgrp->flags); - /* - * If succeeded, set REMOVED and put all the base refs; otherwise, - * restore refcnts to positive values. Either way, all in-progress - * css_tryget() will be released. - */ - for_each_subsys(cgrp->root, ss) { - struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; - - if (!failed) { - set_bit(CSS_REMOVED, &css->flags); - css_put(css); - } else { - atomic_sub(CSS_DEACT_BIAS, &css->refcnt); - } - } - - local_irq_restore(flags); - return !failed; -} - -static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) -{ - struct cgroup *cgrp = dentry->d_fsdata; - struct dentry *d; - struct cgroup *parent; - DEFINE_WAIT(wait); - struct cgroup_event *event, *tmp; - int ret; - - /* the vfs holds both inode->i_mutex already */ -again: - mutex_lock(&cgroup_mutex); - if (atomic_read(&cgrp->count) != 0) { - mutex_unlock(&cgroup_mutex); - return -EBUSY; - } - if (!list_empty(&cgrp->children)) { - mutex_unlock(&cgroup_mutex); - return -EBUSY; - } - mutex_unlock(&cgroup_mutex); + /* tell subsystems to initate destruction */ + for_each_subsys(cgrp->root, ss) + offline_css(ss, cgrp); /* - * In general, subsystem has no css->refcnt after pre_destroy(). But - * in racy cases, subsystem may have to get css->refcnt after - * pre_destroy() and it makes rmdir return with -EBUSY. This sometimes - * make rmdir return -EBUSY too often. To avoid that, we use waitqueue - * for cgroup's rmdir. CGRP_WAIT_ON_RMDIR is for synchronizing rmdir - * and subsystem's reference count handling. Please see css_get/put - * and css_tryget() and cgroup_wakeup_rmdir_waiter() implementation. + * Put all the base refs. Each css holds an extra reference to the + * cgroup's dentry and cgroup removal proceeds regardless of css + * refs. On the last put of each css, whenever that may be, the + * extra dentry ref is put so that dentry destruction happens only + * after all css's are released. */ - set_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); - - /* - * Call pre_destroy handlers of subsys. Notify subsystems - * that rmdir() request comes. - */ - ret = cgroup_call_pre_destroy(cgrp); - if (ret) { - clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); - return ret; - } - - mutex_lock(&cgroup_mutex); - parent = cgrp->parent; - if (atomic_read(&cgrp->count) || !list_empty(&cgrp->children)) { - clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); - mutex_unlock(&cgroup_mutex); - return -EBUSY; - } - prepare_to_wait(&cgroup_rmdir_waitq, &wait, TASK_INTERRUPTIBLE); - if (!cgroup_clear_css_refs(cgrp)) { - mutex_unlock(&cgroup_mutex); - /* - * Because someone may call cgroup_wakeup_rmdir_waiter() before - * prepare_to_wait(), we need to check this flag. - */ - if (test_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags)) - schedule(); - finish_wait(&cgroup_rmdir_waitq, &wait); - clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); - if (signal_pending(current)) - return -EINTR; - goto again; - } - /* NO css_tryget() can success after here. */ - finish_wait(&cgroup_rmdir_waitq, &wait); - clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags); + for_each_subsys(cgrp->root, ss) + css_put(cgrp->subsys[ss->subsys_id]); raw_spin_lock(&release_list_lock); - set_bit(CGRP_REMOVED, &cgrp->flags); if (!list_empty(&cgrp->release_list)) list_del_init(&cgrp->release_list); raw_spin_unlock(&release_list_lock); /* delete this cgroup from parent->children */ - list_del_init(&cgrp->sibling); - + list_del_rcu(&cgrp->sibling); list_del_init(&cgrp->allcg_node); - d = dget(cgrp->dentry); - + dget(d); cgroup_d_remove_dir(d); dput(d); @@ -4222,21 +4341,35 @@ again: /* * Unregister events and notify userspace. * Notify userspace about cgroup removing only after rmdir of cgroup - * directory to avoid race between userspace and kernelspace + * directory to avoid race between userspace and kernelspace. Use + * a temporary list to avoid a deadlock with cgroup_event_wake(). Since + * cgroup_event_wake() is called with the wait queue head locked, + * remove_wait_queue() cannot be called while holding event_list_lock. */ spin_lock(&cgrp->event_list_lock); - list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) { - list_del(&event->list); + list_splice_init(&cgrp->event_list, &tmp_list); + spin_unlock(&cgrp->event_list_lock); + list_for_each_entry_safe(event, tmp, &tmp_list, list) { + list_del_init(&event->list); remove_wait_queue(event->wqh, &event->wait); eventfd_signal(event->eventfd, 1); schedule_work(&event->remove); } - spin_unlock(&cgrp->event_list_lock); - mutex_unlock(&cgroup_mutex); return 0; } +static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) +{ + int ret; + + mutex_lock(&cgroup_mutex); + ret = cgroup_destroy_locked(dentry->d_fsdata); + mutex_unlock(&cgroup_mutex); + + return ret; +} + static void __init_or_module cgroup_init_cftsets(struct cgroup_subsys *ss) { INIT_LIST_HEAD(&ss->cftsets); @@ -4257,13 +4390,15 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss) printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); + mutex_lock(&cgroup_mutex); + /* init base cftset */ cgroup_init_cftsets(ss); /* Create the top cgroup state for this subsystem */ list_add(&ss->sibling, &rootnode.subsys_list); ss->root = &rootnode; - css = ss->create(dummytop); + css = ss->css_alloc(dummytop); /* We don't handle early failures gracefully */ BUG_ON(IS_ERR(css)); init_cgroup_css(css, ss, dummytop); @@ -4272,7 +4407,7 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss) * pointer to this state - since the subsystem is * newly registered, all tasks and hence the * init_css_set is in the subsystem's top cgroup. */ - init_css_set.subsys[ss->subsys_id] = dummytop->subsys[ss->subsys_id]; + init_css_set.subsys[ss->subsys_id] = css; need_forkexit_callback |= ss->fork || ss->exit; @@ -4282,6 +4417,9 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss) BUG_ON(!list_empty(&init_task.tasks)); ss->active = 1; + BUG_ON(online_css(ss, dummytop)); + + mutex_unlock(&cgroup_mutex); /* this function shouldn't be used with modular subsystems, since they * need to register a subsys_id, among other things */ @@ -4299,12 +4437,12 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss) */ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) { - int i; struct cgroup_subsys_state *css; + int i, ret; /* check name and function validity */ if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN || - ss->create == NULL || ss->destroy == NULL) + ss->css_alloc == NULL || ss->css_free == NULL) return -EINVAL; /* @@ -4321,8 +4459,7 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) * since cgroup_init_subsys will have already taken care of it. */ if (ss->module == NULL) { - /* a few sanity checks */ - BUG_ON(ss->subsys_id >= CGROUP_BUILTIN_SUBSYS_COUNT); + /* a sanity check */ BUG_ON(subsys[ss->subsys_id] != ss); return 0; } @@ -4330,33 +4467,18 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) /* init base cftset */ cgroup_init_cftsets(ss); - /* - * need to register a subsys id before anything else - for example, - * init_cgroup_css needs it. - */ mutex_lock(&cgroup_mutex); - /* find the first empty slot in the array */ - for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) { - if (subsys[i] == NULL) - break; - } - if (i == CGROUP_SUBSYS_COUNT) { - /* maximum number of subsystems already registered! */ - mutex_unlock(&cgroup_mutex); - return -EBUSY; - } - /* assign ourselves the subsys_id */ - ss->subsys_id = i; - subsys[i] = ss; + subsys[ss->subsys_id] = ss; /* - * no ss->create seems to need anything important in the ss struct, so - * this can happen first (i.e. before the rootnode attachment). + * no ss->css_alloc seems to need anything important in the ss + * struct, so this can happen first (i.e. before the rootnode + * attachment). */ - css = ss->create(dummytop); + css = ss->css_alloc(dummytop); if (IS_ERR(css)) { /* failure case - need to deassign the subsys[] slot. */ - subsys[i] = NULL; + subsys[ss->subsys_id] = NULL; mutex_unlock(&cgroup_mutex); return PTR_ERR(css); } @@ -4368,14 +4490,9 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) init_cgroup_css(css, ss, dummytop); /* init_idr must be after init_cgroup_css because it sets css->id. */ if (ss->use_id) { - int ret = cgroup_init_idr(ss, css); - if (ret) { - dummytop->subsys[ss->subsys_id] = NULL; - ss->destroy(dummytop); - subsys[i] = NULL; - mutex_unlock(&cgroup_mutex); - return ret; - } + ret = cgroup_init_idr(ss, css); + if (ret) + goto err_unload; } /* @@ -4408,10 +4525,19 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) write_unlock(&css_set_lock); ss->active = 1; + ret = online_css(ss, dummytop); + if (ret) + goto err_unload; /* success! */ mutex_unlock(&cgroup_mutex); return 0; + +err_unload: + mutex_unlock(&cgroup_mutex); + /* @ss can't be mounted here as try_module_get() would fail */ + cgroup_unload_subsys(ss); + return ret; } EXPORT_SYMBOL_GPL(cgroup_load_subsys); @@ -4438,8 +4564,16 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) BUG_ON(ss->root != &rootnode); mutex_lock(&cgroup_mutex); + + offline_css(ss, dummytop); + ss->active = 0; + + if (ss->use_id) { + idr_remove_all(&ss->idr); + idr_destroy(&ss->idr); + } + /* deassign the subsys_id */ - BUG_ON(ss->subsys_id < CGROUP_BUILTIN_SUBSYS_COUNT); subsys[ss->subsys_id] = NULL; /* remove subsystem from rootnode's list of subsystems */ @@ -4454,7 +4588,6 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) struct css_set *cg = link->cg; hlist_del(&cg->hlist); - BUG_ON(!cg->subsys[ss->subsys_id]); cg->subsys[ss->subsys_id] = NULL; hhead = css_set_hash(cg->subsys); hlist_add_head(&cg->hlist, hhead); @@ -4462,12 +4595,12 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) write_unlock(&css_set_lock); /* - * remove subsystem's css from the dummytop and free it - need to free - * before marking as null because ss->destroy needs the cgrp->subsys - * pointer to find their state. note that this also takes care of - * freeing the css_id. + * remove subsystem's css from the dummytop and free it - need to + * free before marking as null because ss->css_free needs the + * cgrp->subsys pointer to find their state. note that this also + * takes care of freeing the css_id. */ - ss->destroy(dummytop); + ss->css_free(dummytop); dummytop->subsys[ss->subsys_id] = NULL; mutex_unlock(&cgroup_mutex); @@ -4502,14 +4635,17 @@ int __init cgroup_init_early(void) for (i = 0; i < CSS_SET_TABLE_SIZE; i++) INIT_HLIST_HEAD(&css_set_table[i]); - /* at bootup time, we don't worry about modular subsystems */ - for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { + for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { struct cgroup_subsys *ss = subsys[i]; + /* at bootup time, we don't worry about modular subsystems */ + if (!ss || ss->module) + continue; + BUG_ON(!ss->name); BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN); - BUG_ON(!ss->create); - BUG_ON(!ss->destroy); + 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); @@ -4538,9 +4674,12 @@ int __init cgroup_init(void) if (err) return err; - /* at bootup time, we don't worry about modular subsystems */ - for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { + for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { struct cgroup_subsys *ss = subsys[i]; + + /* at bootup time, we don't worry about modular subsystems */ + if (!ss || ss->module) + continue; if (!ss->early_init) cgroup_init_subsys(ss); if (ss->use_id) @@ -4695,70 +4834,37 @@ static const struct file_operations proc_cgroupstats_operations = { * * 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, cgroup_mutex or - * threadgroup_change_begin(), so it 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. - * - * Outside the pointer validity we also need to process the css_set - * inheritance between threadgoup_change_begin() and - * threadgoup_change_end(), this way there is no leak in any process - * wide migration performed by cgroup_attach_proc() that could otherwise - * miss a thread because it is too early or too late in the fork stage. + * 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) { - /* - * We don't need to task_lock() current because current->cgroups - * can't be changed concurrently here. The parent obviously hasn't - * exited and called cgroup_exit(), and we are synchronized against - * cgroup migration through threadgroup_change_begin(). - */ + task_lock(current); child->cgroups = current->cgroups; get_css_set(child->cgroups); + task_unlock(current); INIT_LIST_HEAD(&child->cg_list); } /** - * cgroup_fork_callbacks - run fork callbacks - * @child: the new task - * - * Called on a new task very soon before adding it to the - * tasklist. No need to take any locks since no-one can - * be operating on this task. - */ -void cgroup_fork_callbacks(struct task_struct *child) -{ - if (need_forkexit_callback) { - int i; - /* - * forkexit callbacks are only supported for builtin - * subsystems, and the builtin section of the subsys array is - * immutable, so we don't need to lock the subsys array here. - */ - for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { - struct cgroup_subsys *ss = subsys[i]; - if (ss->fork) - ss->fork(child); - } - } -} - -/** * cgroup_post_fork - called on a new task after adding it to the task list * @child: the task in question * - * Adds the task to the list running through its css_set if necessary. - * 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. + * Adds the task to the list running through its css_set if necessary and + * call the subsystem fork() callbacks. Has to be after the task is + * visible on the task list in case we race with the first call to + * cgroup_iter_start() - to guarantee that the new task ends up on its + * list. */ void cgroup_post_fork(struct task_struct *child) { + int i; + /* * use_task_css_set_links is set to 1 before we walk the tasklist * under the tasklist_lock and we read it here after we added the child @@ -4772,22 +4878,36 @@ void cgroup_post_fork(struct task_struct *child) */ if (use_task_css_set_links) { write_lock(&css_set_lock); - if (list_empty(&child->cg_list)) { + task_lock(child); + if (list_empty(&child->cg_list)) + list_add(&child->cg_list, &child->cgroups->tasks); + task_unlock(child); + write_unlock(&css_set_lock); + } + + /* + * Call ss->fork(). This must happen after @child is linked on + * css_set; otherwise, @child might change state between ->fork() + * and addition to css_set. + */ + if (need_forkexit_callback) { + for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { + struct cgroup_subsys *ss = subsys[i]; + /* - * It's safe to use child->cgroups without task_lock() - * here because we are protected through - * threadgroup_change_begin() against concurrent - * css_set change in cgroup_task_migrate(). Also - * the task can't exit at that point until - * wake_up_new_task() is called, so we are protected - * against cgroup_exit() setting child->cgroup to - * init_css_set. + * fork/exit callbacks are supported only for + * builtin subsystems and we don't need further + * synchronization as they never go away. */ - list_add(&child->cg_list, &child->cgroups->tasks); + if (!ss || ss->module) + continue; + + if (ss->fork) + ss->fork(child); } - write_unlock(&css_set_lock); } } + /** * cgroup_exit - detach cgroup from exiting task * @tsk: pointer to task_struct of exiting process @@ -4846,12 +4966,13 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks) tsk->cgroups = &init_css_set; if (run_callbacks && need_forkexit_callback) { - /* - * modular subsystems can't use callbacks, so no need to lock - * the subsys array - */ - for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { + for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { struct cgroup_subsys *ss = subsys[i]; + + /* modular subsystems can't use callbacks */ + if (!ss || ss->module) + continue; + if (ss->exit) { struct cgroup *old_cgrp = rcu_dereference_raw(cg->subsys[i])->cgroup; @@ -4919,15 +5040,17 @@ static void check_for_release(struct cgroup *cgrp) /* Caller must verify that the css is not for root cgroup */ bool __css_tryget(struct cgroup_subsys_state *css) { - do { - int v = css_refcnt(css); + while (true) { + int t, v; - if (atomic_cmpxchg(&css->refcnt, v, v + 1) == v) + v = css_refcnt(css); + t = atomic_cmpxchg(&css->refcnt, v, v + 1); + if (likely(t == v)) return true; + else if (t < 0) + return false; cpu_relax(); - } while (!test_bit(CSS_REMOVED, &css->flags)); - - return false; + } } EXPORT_SYMBOL_GPL(__css_tryget); @@ -4946,11 +5069,9 @@ void __css_put(struct cgroup_subsys_state *css) set_bit(CGRP_RELEASABLE, &cgrp->flags); check_for_release(cgrp); } - cgroup_wakeup_rmdir_waiter(cgrp); break; case 0: - if (!test_bit(CSS_CLEAR_CSS_REFS, &css->flags)) - schedule_work(&css->dput_work); + schedule_work(&css->dput_work); break; } rcu_read_unlock(); @@ -5037,13 +5158,17 @@ static int __init cgroup_disable(char *str) 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 (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { + for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { struct cgroup_subsys *ss = subsys[i]; + /* + * cgroup_disable, being at boot time, can't + * know about module subsystems, so we don't + * worry about them. + */ + if (!ss || ss->module) + continue; + if (!strcmp(token, ss->name)) { ss->disabled = 1; printk(KERN_INFO "Disabling %s control group" @@ -5332,7 +5457,7 @@ struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id) } #ifdef CONFIG_CGROUP_DEBUG -static struct cgroup_subsys_state *debug_create(struct cgroup *cont) +static struct cgroup_subsys_state *debug_css_alloc(struct cgroup *cont) { struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); @@ -5342,7 +5467,7 @@ static struct cgroup_subsys_state *debug_create(struct cgroup *cont) return css; } -static void debug_destroy(struct cgroup *cont) +static void debug_css_free(struct cgroup *cont) { kfree(cont->subsys[debug_subsys_id]); } @@ -5471,8 +5596,8 @@ static struct cftype debug_files[] = { struct cgroup_subsys debug_subsys = { .name = "debug", - .create = debug_create, - .destroy = debug_destroy, + .css_alloc = debug_css_alloc, + .css_free = debug_css_free, .subsys_id = debug_subsys_id, .base_cftypes = debug_files, }; |