diff options
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 1825 |
1 files changed, 1181 insertions, 644 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index ceee0c54c6a4..7868fc3c0bc5 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -26,6 +26,8 @@ * distribution for more details. */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + #include <linux/cgroup.h> #include <linux/cred.h> #include <linux/ctype.h> @@ -70,15 +72,6 @@ MAX_CFTYPE_NAME + 2) /* - * cgroup_tree_mutex nests above cgroup_mutex and protects cftypes, file - * creation/removal and hierarchy changing operations including cgroup - * creation, removal, css association and controller rebinding. This outer - * lock is needed mainly to resolve the circular dependency between kernfs - * active ref and cgroup_mutex. cgroup_tree_mutex nests above both. - */ -static DEFINE_MUTEX(cgroup_tree_mutex); - -/* * cgroup_mutex is the master lock. Any modification to cgroup or its * hierarchy must be performed while holding it. * @@ -99,16 +92,21 @@ static DECLARE_RWSEM(css_set_rwsem); #endif /* + * Protects cgroup_idr and css_idr so that IDs can be released without + * grabbing cgroup_mutex. + */ +static DEFINE_SPINLOCK(cgroup_idr_lock); + +/* * Protects cgroup_subsys->release_agent_path. Modifying it also requires * cgroup_mutex. Reading requires either cgroup_mutex or this spinlock. */ static DEFINE_SPINLOCK(release_agent_path_lock); -#define cgroup_assert_mutexes_or_rcu_locked() \ +#define cgroup_assert_mutex_or_rcu_locked() \ rcu_lockdep_assert(rcu_read_lock_held() || \ - lockdep_is_held(&cgroup_tree_mutex) || \ lockdep_is_held(&cgroup_mutex), \ - "cgroup_[tree_]mutex or RCU read lock required"); + "cgroup_mutex or RCU read lock required"); /* * cgroup destruction makes heavy use of work items and there can be a lot @@ -151,6 +149,13 @@ struct cgroup_root cgrp_dfl_root; */ static bool cgrp_dfl_root_visible; +/* some controllers are not supported in the default hierarchy */ +static const unsigned int cgrp_dfl_root_inhibit_ss_mask = 0 +#ifdef CONFIG_CGROUP_DEBUG + | (1 << debug_cgrp_id) +#endif + ; + /* The list of hierarchy roots */ static LIST_HEAD(cgroup_roots); @@ -160,14 +165,13 @@ static int cgroup_root_count; static DEFINE_IDR(cgroup_hierarchy_idr); /* - * 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. + * Assign a monotonically increasing serial number to csses. It guarantees + * cgroups with bigger numbers are newer than those with smaller numbers. + * Also, as csses are always appended to the parent's ->children list, it + * guarantees that sibling csses are always sorted in the ascending serial + * number order on the list. Protected by cgroup_mutex. */ -static u64 cgroup_serial_nr_next = 1; +static u64 css_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 @@ -180,17 +184,59 @@ static struct cftype cgroup_base_files[]; static void cgroup_put(struct cgroup *cgrp); static int rebind_subsystems(struct cgroup_root *dst_root, - unsigned long ss_mask); -static void cgroup_destroy_css_killed(struct cgroup *cgrp); + unsigned int ss_mask); static int cgroup_destroy_locked(struct cgroup *cgrp); +static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss); +static void css_release(struct percpu_ref *ref); +static void kill_css(struct cgroup_subsys_state *css); static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], bool is_add); static void cgroup_pidlist_destroy_all(struct cgroup *cgrp); +/* IDR wrappers which synchronize using cgroup_idr_lock */ +static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end, + gfp_t gfp_mask) +{ + int ret; + + idr_preload(gfp_mask); + spin_lock_bh(&cgroup_idr_lock); + ret = idr_alloc(idr, ptr, start, end, gfp_mask); + spin_unlock_bh(&cgroup_idr_lock); + idr_preload_end(); + return ret; +} + +static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id) +{ + void *ret; + + spin_lock_bh(&cgroup_idr_lock); + ret = idr_replace(idr, ptr, id); + spin_unlock_bh(&cgroup_idr_lock); + return ret; +} + +static void cgroup_idr_remove(struct idr *idr, int id) +{ + spin_lock_bh(&cgroup_idr_lock); + idr_remove(idr, id); + spin_unlock_bh(&cgroup_idr_lock); +} + +static struct cgroup *cgroup_parent(struct cgroup *cgrp) +{ + struct cgroup_subsys_state *parent_css = cgrp->self.parent; + + if (parent_css) + return container_of(parent_css, struct cgroup, self); + return NULL; +} + /** * cgroup_css - obtain a cgroup's css for the specified subsystem * @cgrp: the cgroup of interest - * @ss: the subsystem of interest (%NULL returns the dummy_css) + * @ss: the subsystem of interest (%NULL returns @cgrp->self) * * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This * function must be called either under cgroup_mutex or rcu_read_lock() and @@ -203,23 +249,49 @@ static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp, { if (ss) return rcu_dereference_check(cgrp->subsys[ss->id], - lockdep_is_held(&cgroup_tree_mutex) || lockdep_is_held(&cgroup_mutex)); else - return &cgrp->dummy_css; + return &cgrp->self; +} + +/** + * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem + * @cgrp: the cgroup of interest + * @ss: the subsystem of interest (%NULL returns @cgrp->self) + * + * Similar to cgroup_css() but returns the effctive css, which is defined + * as the matching css of the nearest ancestor including self which has @ss + * enabled. If @ss is associated with the hierarchy @cgrp is on, this + * function is guaranteed to return non-NULL css. + */ +static struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp, + struct cgroup_subsys *ss) +{ + lockdep_assert_held(&cgroup_mutex); + + if (!ss) + return &cgrp->self; + + if (!(cgrp->root->subsys_mask & (1 << ss->id))) + return NULL; + + while (cgroup_parent(cgrp) && + !(cgroup_parent(cgrp)->child_subsys_mask & (1 << ss->id))) + cgrp = cgroup_parent(cgrp); + + return cgroup_css(cgrp, ss); } /* convenient tests for these bits */ static inline bool cgroup_is_dead(const struct cgroup *cgrp) { - return test_bit(CGRP_DEAD, &cgrp->flags); + return !(cgrp->self.flags & CSS_ONLINE); } -struct cgroup_subsys_state *seq_css(struct seq_file *seq) +struct cgroup_subsys_state *of_css(struct kernfs_open_file *of) { - struct kernfs_open_file *of = seq->private; struct cgroup *cgrp = of->kn->parent->priv; - struct cftype *cft = seq_cft(seq); + struct cftype *cft = of_cft(of); /* * This is open and unprotected implementation of cgroup_css(). @@ -232,9 +304,9 @@ struct cgroup_subsys_state *seq_css(struct seq_file *seq) if (cft->ss) return rcu_dereference_raw(cgrp->subsys[cft->ss->id]); else - return &cgrp->dummy_css; + return &cgrp->self; } -EXPORT_SYMBOL_GPL(seq_css); +EXPORT_SYMBOL_GPL(of_css); /** * cgroup_is_descendant - test ancestry @@ -250,7 +322,7 @@ bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor) while (cgrp) { if (cgrp == ancestor) return true; - cgrp = cgrp->parent; + cgrp = cgroup_parent(cgrp); } return false; } @@ -274,17 +346,30 @@ static int notify_on_release(const struct cgroup *cgrp) * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end * @cgrp: the target cgroup to iterate css's of * - * Should be called under cgroup_mutex. + * Should be called under cgroup_[tree_]mutex. */ #define for_each_css(css, ssid, cgrp) \ for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ if (!((css) = rcu_dereference_check( \ (cgrp)->subsys[(ssid)], \ - lockdep_is_held(&cgroup_tree_mutex) || \ lockdep_is_held(&cgroup_mutex)))) { } \ else /** + * for_each_e_css - iterate all effective css's of a cgroup + * @css: the iteration cursor + * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end + * @cgrp: the target cgroup to iterate css's of + * + * Should be called under cgroup_[tree_]mutex. + */ +#define for_each_e_css(css, ssid, cgrp) \ + for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ + if (!((css) = cgroup_e_css(cgrp, cgroup_subsys[(ssid)]))) \ + ; \ + else + +/** * for_each_subsys - iterate all enabled cgroup subsystems * @ss: the iteration cursor * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end @@ -297,22 +382,13 @@ static int notify_on_release(const struct cgroup *cgrp) #define for_each_root(root) \ list_for_each_entry((root), &cgroup_roots, root_list) -/** - * 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; -} +/* iterate over child cgrps, lock should be held throughout iteration */ +#define cgroup_for_each_live_child(child, cgrp) \ + list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \ + if (({ lockdep_assert_held(&cgroup_mutex); \ + cgroup_is_dead(child); })) \ + ; \ + else /* the list of cgroups eligible for automatic release. Protected by * release_list_lock */ @@ -360,6 +436,43 @@ struct css_set init_css_set = { static int css_set_count = 1; /* 1 for init_css_set */ +/** + * cgroup_update_populated - updated populated count of a cgroup + * @cgrp: the target cgroup + * @populated: inc or dec populated count + * + * @cgrp is either getting the first task (css_set) or losing the last. + * Update @cgrp->populated_cnt accordingly. The count is propagated + * towards root so that a given cgroup's populated_cnt is zero iff the + * cgroup and all its descendants are empty. + * + * @cgrp's interface file "cgroup.populated" is zero if + * @cgrp->populated_cnt is zero and 1 otherwise. When @cgrp->populated_cnt + * changes from or to zero, userland is notified that the content of the + * interface file has changed. This can be used to detect when @cgrp and + * its descendants become populated or empty. + */ +static void cgroup_update_populated(struct cgroup *cgrp, bool populated) +{ + lockdep_assert_held(&css_set_rwsem); + + do { + bool trigger; + + if (populated) + trigger = !cgrp->populated_cnt++; + else + trigger = !--cgrp->populated_cnt; + + if (!trigger) + break; + + if (cgrp->populated_kn) + kernfs_notify(cgrp->populated_kn); + cgrp = cgroup_parent(cgrp); + } while (cgrp); +} + /* * hash table for cgroup groups. This improves the performance to find * an existing css_set. This hash doesn't (currently) take into @@ -384,6 +497,8 @@ static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) static void put_css_set_locked(struct css_set *cset, bool taskexit) { struct cgrp_cset_link *link, *tmp_link; + struct cgroup_subsys *ss; + int ssid; lockdep_assert_held(&css_set_rwsem); @@ -391,6 +506,8 @@ static void put_css_set_locked(struct css_set *cset, bool taskexit) return; /* This css_set is dead. unlink it and release cgroup refcounts */ + for_each_subsys(ss, ssid) + list_del(&cset->e_cset_node[ssid]); hash_del(&cset->hlist); css_set_count--; @@ -401,10 +518,13 @@ static void put_css_set_locked(struct css_set *cset, bool taskexit) list_del(&link->cgrp_link); /* @cgrp can't go away while we're holding css_set_rwsem */ - if (list_empty(&cgrp->cset_links) && notify_on_release(cgrp)) { - if (taskexit) - set_bit(CGRP_RELEASABLE, &cgrp->flags); - check_for_release(cgrp); + if (list_empty(&cgrp->cset_links)) { + cgroup_update_populated(cgrp, false); + if (notify_on_release(cgrp)) { + if (taskexit) + set_bit(CGRP_RELEASABLE, &cgrp->flags); + check_for_release(cgrp); + } } kfree(link); @@ -453,20 +573,20 @@ static bool compare_css_sets(struct css_set *cset, { struct list_head *l1, *l2; - if (memcmp(template, cset->subsys, sizeof(cset->subsys))) { - /* Not all subsystems matched */ + /* + * On the default hierarchy, there can be csets which are + * associated with the same set of cgroups but different csses. + * Let's first ensure that csses match. + */ + if (memcmp(template, cset->subsys, sizeof(cset->subsys))) return false; - } /* * Compare cgroup pointers in order to distinguish between - * different cgroups in 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. + * different cgroups in hierarchies. As different cgroups may + * share the same effective css, this comparison is always + * necessary. */ - l1 = &cset->cgrp_links; l2 = &old_cset->cgrp_links; while (1) { @@ -530,14 +650,17 @@ static struct css_set *find_existing_css_set(struct css_set *old_cset, * won't change, so no need for locking. */ for_each_subsys(ss, i) { - if (root->cgrp.subsys_mask & (1UL << i)) { - /* Subsystem is in this hierarchy. So we want - * the subsystem state from the new - * cgroup */ - template[i] = cgroup_css(cgrp, ss); + if (root->subsys_mask & (1UL << i)) { + /* + * @ss is in this hierarchy, so we want the + * effective css from @cgrp. + */ + template[i] = cgroup_e_css(cgrp, ss); } else { - /* Subsystem is not in this hierarchy, so we - * don't want to change the subsystem state */ + /* + * @ss is not in this hierarchy, so we don't want + * to change the css. + */ template[i] = old_cset->subsys[i]; } } @@ -603,10 +726,18 @@ static void link_css_set(struct list_head *tmp_links, struct css_set *cset, struct cgrp_cset_link *link; BUG_ON(list_empty(tmp_links)); + + if (cgroup_on_dfl(cgrp)) + cset->dfl_cgrp = cgrp; + link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link); link->cset = cset; link->cgrp = cgrp; + + if (list_empty(&cgrp->cset_links)) + cgroup_update_populated(cgrp, true); 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 @@ -629,7 +760,9 @@ static struct css_set *find_css_set(struct css_set *old_cset, struct css_set *cset; struct list_head tmp_links; struct cgrp_cset_link *link; + struct cgroup_subsys *ss; unsigned long key; + int ssid; lockdep_assert_held(&cgroup_mutex); @@ -680,10 +813,14 @@ static struct css_set *find_css_set(struct css_set *old_cset, css_set_count++; - /* Add this cgroup group to the hash table */ + /* Add @cset to the hash table */ key = css_set_hash(cset->subsys); hash_add(css_set_table, &cset->hlist, key); + for_each_subsys(ss, ssid) + list_add_tail(&cset->e_cset_node[ssid], + &cset->subsys[ssid]->cgroup->e_csets[ssid]); + up_write(&css_set_rwsem); return cset; @@ -736,14 +873,13 @@ static void cgroup_destroy_root(struct cgroup_root *root) struct cgroup *cgrp = &root->cgrp; struct cgrp_cset_link *link, *tmp_link; - mutex_lock(&cgroup_tree_mutex); mutex_lock(&cgroup_mutex); BUG_ON(atomic_read(&root->nr_cgrps)); - BUG_ON(!list_empty(&cgrp->children)); + BUG_ON(!list_empty(&cgrp->self.children)); /* Rebind all subsystems back to the default hierarchy */ - rebind_subsystems(&cgrp_dfl_root, cgrp->subsys_mask); + rebind_subsystems(&cgrp_dfl_root, root->subsys_mask); /* * Release all the links from cset_links to this hierarchy's @@ -766,7 +902,6 @@ static void cgroup_destroy_root(struct cgroup_root *root) cgroup_exit_root_id(root); mutex_unlock(&cgroup_mutex); - mutex_unlock(&cgroup_tree_mutex); kernfs_destroy_root(root->kf_root); cgroup_free_root(root); @@ -849,7 +984,7 @@ static struct cgroup *task_cgroup_from_root(struct task_struct *task, * update of a tasks cgroup pointer by cgroup_attach_task() */ -static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask); +static int cgroup_populate_dir(struct cgroup *cgrp, unsigned int subsys_mask); static struct kernfs_syscall_ops cgroup_kf_syscall_ops; static const struct file_operations proc_cgroupstats_operations; @@ -884,79 +1019,95 @@ static umode_t cgroup_file_mode(const struct cftype *cft) if (cft->read_u64 || cft->read_s64 || cft->seq_show) mode |= S_IRUGO; - if (cft->write_u64 || cft->write_s64 || cft->write_string || - cft->trigger) + if (cft->write_u64 || cft->write_s64 || cft->write) mode |= S_IWUSR; return mode; } -static void cgroup_free_fn(struct work_struct *work) +static void cgroup_get(struct cgroup *cgrp) { - struct cgroup *cgrp = container_of(work, struct cgroup, destroy_work); - - atomic_dec(&cgrp->root->nr_cgrps); - cgroup_pidlist_destroy_all(cgrp); - - if (cgrp->parent) { - /* - * We get a ref to the parent, and put the ref when this - * cgroup is being freed, so it's guaranteed that the - * parent won't be destroyed before its children. - */ - cgroup_put(cgrp->parent); - kernfs_put(cgrp->kn); - kfree(cgrp); - } else { - /* - * This is root cgroup's refcnt reaching zero, which - * indicates that the root should be released. - */ - cgroup_destroy_root(cgrp->root); - } + WARN_ON_ONCE(cgroup_is_dead(cgrp)); + css_get(&cgrp->self); } -static void cgroup_free_rcu(struct rcu_head *head) +static void cgroup_put(struct cgroup *cgrp) { - struct cgroup *cgrp = container_of(head, struct cgroup, rcu_head); - - INIT_WORK(&cgrp->destroy_work, cgroup_free_fn); - queue_work(cgroup_destroy_wq, &cgrp->destroy_work); + css_put(&cgrp->self); } -static void cgroup_get(struct cgroup *cgrp) +/** + * cgroup_kn_unlock - unlocking helper for cgroup kernfs methods + * @kn: the kernfs_node being serviced + * + * This helper undoes cgroup_kn_lock_live() and should be invoked before + * the method finishes if locking succeeded. Note that once this function + * returns the cgroup returned by cgroup_kn_lock_live() may become + * inaccessible any time. If the caller intends to continue to access the + * cgroup, it should pin it before invoking this function. + */ +static void cgroup_kn_unlock(struct kernfs_node *kn) { - WARN_ON_ONCE(cgroup_is_dead(cgrp)); - WARN_ON_ONCE(atomic_read(&cgrp->refcnt) <= 0); - atomic_inc(&cgrp->refcnt); + struct cgroup *cgrp; + + if (kernfs_type(kn) == KERNFS_DIR) + cgrp = kn->priv; + else + cgrp = kn->parent->priv; + + mutex_unlock(&cgroup_mutex); + + kernfs_unbreak_active_protection(kn); + cgroup_put(cgrp); } -static void cgroup_put(struct cgroup *cgrp) +/** + * cgroup_kn_lock_live - locking helper for cgroup kernfs methods + * @kn: the kernfs_node being serviced + * + * This helper is to be used by a cgroup kernfs method currently servicing + * @kn. It breaks the active protection, performs cgroup locking and + * verifies that the associated cgroup is alive. Returns the cgroup if + * alive; otherwise, %NULL. A successful return should be undone by a + * matching cgroup_kn_unlock() invocation. + * + * Any cgroup kernfs method implementation which requires locking the + * associated cgroup should use this helper. It avoids nesting cgroup + * locking under kernfs active protection and allows all kernfs operations + * including self-removal. + */ +static struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn) { - if (!atomic_dec_and_test(&cgrp->refcnt)) - return; - if (WARN_ON_ONCE(cgrp->parent && !cgroup_is_dead(cgrp))) - return; + struct cgroup *cgrp; + + if (kernfs_type(kn) == KERNFS_DIR) + cgrp = kn->priv; + else + cgrp = kn->parent->priv; /* - * XXX: cgrp->id is only used to look up css's. As cgroup and - * css's lifetimes will be decoupled, it should be made - * per-subsystem and moved to css->id so that lookups are - * successful until the target css is released. + * We're gonna grab cgroup_mutex which nests outside kernfs + * active_ref. cgroup liveliness check alone provides enough + * protection against removal. Ensure @cgrp stays accessible and + * break the active_ref protection. */ + cgroup_get(cgrp); + kernfs_break_active_protection(kn); + mutex_lock(&cgroup_mutex); - idr_remove(&cgrp->root->cgroup_idr, cgrp->id); - mutex_unlock(&cgroup_mutex); - cgrp->id = -1; - call_rcu(&cgrp->rcu_head, cgroup_free_rcu); + if (!cgroup_is_dead(cgrp)) + return cgrp; + + cgroup_kn_unlock(kn); + return NULL; } static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) { char name[CGROUP_FILE_NAME_MAX]; - lockdep_assert_held(&cgroup_tree_mutex); + lockdep_assert_held(&cgroup_mutex); kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name)); } @@ -965,7 +1116,7 @@ static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) * @cgrp: target cgroup * @subsys_mask: mask of the subsystem ids whose files should be removed */ -static void cgroup_clear_dir(struct cgroup *cgrp, unsigned long subsys_mask) +static void cgroup_clear_dir(struct cgroup *cgrp, unsigned int subsys_mask) { struct cgroup_subsys *ss; int i; @@ -973,40 +1124,40 @@ static void cgroup_clear_dir(struct cgroup *cgrp, unsigned long subsys_mask) for_each_subsys(ss, i) { struct cftype *cfts; - if (!test_bit(i, &subsys_mask)) + if (!(subsys_mask & (1 << i))) continue; list_for_each_entry(cfts, &ss->cfts, node) cgroup_addrm_files(cgrp, cfts, false); } } -static int rebind_subsystems(struct cgroup_root *dst_root, - unsigned long ss_mask) +static int rebind_subsystems(struct cgroup_root *dst_root, unsigned int ss_mask) { struct cgroup_subsys *ss; - int ssid, ret; + unsigned int tmp_ss_mask; + int ssid, i, ret; - lockdep_assert_held(&cgroup_tree_mutex); lockdep_assert_held(&cgroup_mutex); for_each_subsys(ss, ssid) { if (!(ss_mask & (1 << ssid))) continue; - /* if @ss is on the dummy_root, we can always move it */ - if (ss->root == &cgrp_dfl_root) - continue; - - /* if @ss has non-root cgroups attached to it, can't move */ - if (!list_empty(&ss->root->cgrp.children)) + /* if @ss has non-root csses attached to it, can't move */ + if (css_next_child(NULL, cgroup_css(&ss->root->cgrp, ss))) return -EBUSY; /* can't move between two non-dummy roots either */ - if (dst_root != &cgrp_dfl_root) + if (ss->root != &cgrp_dfl_root && dst_root != &cgrp_dfl_root) return -EBUSY; } - ret = cgroup_populate_dir(&dst_root->cgrp, ss_mask); + /* skip creating root files on dfl_root for inhibited subsystems */ + tmp_ss_mask = ss_mask; + if (dst_root == &cgrp_dfl_root) + tmp_ss_mask &= ~cgrp_dfl_root_inhibit_ss_mask; + + ret = cgroup_populate_dir(&dst_root->cgrp, tmp_ss_mask); if (ret) { if (dst_root != &cgrp_dfl_root) return ret; @@ -1018,9 +1169,9 @@ static int rebind_subsystems(struct cgroup_root *dst_root, * Just warn about it and continue. */ if (cgrp_dfl_root_visible) { - pr_warning("cgroup: failed to create files (%d) while rebinding 0x%lx to default root\n", - ret, ss_mask); - pr_warning("cgroup: you may retry by moving them to a different hierarchy and unbinding\n"); + pr_warn("failed to create files (%d) while rebinding 0x%x to default root\n", + ret, ss_mask); + pr_warn("you may retry by moving them to a different hierarchy and unbinding\n"); } } @@ -1028,15 +1179,14 @@ static int rebind_subsystems(struct cgroup_root *dst_root, * Nothing can fail from this point on. Remove files for the * removed subsystems and rebind each subsystem. */ - mutex_unlock(&cgroup_mutex); for_each_subsys(ss, ssid) if (ss_mask & (1 << ssid)) cgroup_clear_dir(&ss->root->cgrp, 1 << ssid); - mutex_lock(&cgroup_mutex); for_each_subsys(ss, ssid) { struct cgroup_root *src_root; struct cgroup_subsys_state *css; + struct css_set *cset; if (!(ss_mask & (1 << ssid))) continue; @@ -1051,8 +1201,19 @@ static int rebind_subsystems(struct cgroup_root *dst_root, ss->root = dst_root; css->cgroup = &dst_root->cgrp; - src_root->cgrp.subsys_mask &= ~(1 << ssid); - dst_root->cgrp.subsys_mask |= 1 << ssid; + down_write(&css_set_rwsem); + hash_for_each(css_set_table, i, cset, hlist) + list_move_tail(&cset->e_cset_node[ss->id], + &dst_root->cgrp.e_csets[ss->id]); + up_write(&css_set_rwsem); + + src_root->subsys_mask &= ~(1 << ssid); + src_root->cgrp.child_subsys_mask &= ~(1 << ssid); + + /* default hierarchy doesn't enable controllers by default */ + dst_root->subsys_mask |= 1 << ssid; + if (dst_root != &cgrp_dfl_root) + dst_root->cgrp.child_subsys_mask |= 1 << ssid; if (ss->bind) ss->bind(css); @@ -1070,7 +1231,7 @@ static int cgroup_show_options(struct seq_file *seq, int ssid; for_each_subsys(ss, ssid) - if (root->cgrp.subsys_mask & (1 << ssid)) + if (root->subsys_mask & (1 << ssid)) seq_printf(seq, ",%s", ss->name); if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) seq_puts(seq, ",sane_behavior"); @@ -1092,8 +1253,8 @@ static int cgroup_show_options(struct seq_file *seq, } struct cgroup_sb_opts { - unsigned long subsys_mask; - unsigned long flags; + unsigned int subsys_mask; + unsigned int flags; char *release_agent; bool cpuset_clone_children; char *name; @@ -1101,24 +1262,16 @@ struct cgroup_sb_opts { bool none; }; -/* - * 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; + unsigned int mask = -1U; struct cgroup_subsys *ss; int i; - BUG_ON(!mutex_is_locked(&cgroup_mutex)); - #ifdef CONFIG_CPUSETS - mask = ~(1UL << cpuset_cgrp_id); + mask = ~(1U << cpuset_cgrp_id); #endif memset(opts, 0, sizeof(*opts)); @@ -1199,7 +1352,7 @@ 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_mask); + opts->subsys_mask |= (1 << i); one_ss = true; break; @@ -1211,12 +1364,12 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) /* 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"); + pr_warn("sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n"); if ((opts->flags & (CGRP_ROOT_NOPREFIX | CGRP_ROOT_XATTR)) || opts->cpuset_clone_children || opts->release_agent || opts->name) { - pr_err("cgroup: sane_behavior: noprefix, xattr, clone_children, release_agent and name are not allowed\n"); + pr_err("sane_behavior: noprefix, xattr, clone_children, release_agent and name are not allowed\n"); return -EINVAL; } } else { @@ -1228,7 +1381,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) if (all_ss || (!one_ss && !opts->none && !opts->name)) for_each_subsys(ss, i) if (!ss->disabled) - set_bit(i, &opts->subsys_mask); + opts->subsys_mask |= (1 << i); /* * We either have to specify by name or by subsystems. (So @@ -1259,14 +1412,13 @@ static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data) int ret = 0; struct cgroup_root *root = cgroup_root_from_kf(kf_root); struct cgroup_sb_opts opts; - unsigned long added_mask, removed_mask; + unsigned int added_mask, removed_mask; if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) { - pr_err("cgroup: sane_behavior: remount is not allowed\n"); + pr_err("sane_behavior: remount is not allowed\n"); return -EINVAL; } - mutex_lock(&cgroup_tree_mutex); mutex_lock(&cgroup_mutex); /* See what subsystems are wanted */ @@ -1274,17 +1426,17 @@ static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data) if (ret) goto out_unlock; - if (opts.subsys_mask != root->cgrp.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); + if (opts.subsys_mask != root->subsys_mask || opts.release_agent) + pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n", + task_tgid_nr(current), current->comm); - added_mask = opts.subsys_mask & ~root->cgrp.subsys_mask; - removed_mask = root->cgrp.subsys_mask & ~opts.subsys_mask; + 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", + pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n", opts.flags & CGRP_ROOT_OPTION_MASK, opts.name ?: "", root->flags & CGRP_ROOT_OPTION_MASK, root->name); ret = -EINVAL; @@ -1292,7 +1444,7 @@ static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data) } /* remounting is not allowed for populated hierarchies */ - if (!list_empty(&root->cgrp.children)) { + if (!list_empty(&root->cgrp.self.children)) { ret = -EBUSY; goto out_unlock; } @@ -1312,7 +1464,6 @@ static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data) kfree(opts.release_agent); kfree(opts.name); mutex_unlock(&cgroup_mutex); - mutex_unlock(&cgroup_tree_mutex); return ret; } @@ -1370,14 +1521,22 @@ out_unlock: static void init_cgroup_housekeeping(struct cgroup *cgrp) { - atomic_set(&cgrp->refcnt, 1); - INIT_LIST_HEAD(&cgrp->sibling); - INIT_LIST_HEAD(&cgrp->children); + struct cgroup_subsys *ss; + int ssid; + + INIT_LIST_HEAD(&cgrp->self.sibling); + INIT_LIST_HEAD(&cgrp->self.children); INIT_LIST_HEAD(&cgrp->cset_links); INIT_LIST_HEAD(&cgrp->release_list); INIT_LIST_HEAD(&cgrp->pidlists); mutex_init(&cgrp->pidlist_mutex); - cgrp->dummy_css.cgroup = cgrp; + cgrp->self.cgroup = cgrp; + cgrp->self.flags |= CSS_ONLINE; + + for_each_subsys(ss, ssid) + INIT_LIST_HEAD(&cgrp->e_csets[ssid]); + + init_waitqueue_head(&cgrp->offline_waitq); } static void init_cgroup_root(struct cgroup_root *root, @@ -1400,21 +1559,24 @@ static void init_cgroup_root(struct cgroup_root *root, set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags); } -static int cgroup_setup_root(struct cgroup_root *root, unsigned long ss_mask) +static int cgroup_setup_root(struct cgroup_root *root, unsigned int ss_mask) { LIST_HEAD(tmp_links); struct cgroup *root_cgrp = &root->cgrp; struct css_set *cset; int i, ret; - lockdep_assert_held(&cgroup_tree_mutex); lockdep_assert_held(&cgroup_mutex); - ret = idr_alloc(&root->cgroup_idr, root_cgrp, 0, 1, GFP_KERNEL); + ret = cgroup_idr_alloc(&root->cgroup_idr, root_cgrp, 1, 2, GFP_NOWAIT); if (ret < 0) goto out; root_cgrp->id = ret; + ret = percpu_ref_init(&root_cgrp->self.refcnt, css_release); + if (ret) + goto out; + /* * We're accessing css_set_count without locking css_set_rwsem here, * but that's OK - it can only be increased by someone holding @@ -1423,11 +1585,11 @@ static int cgroup_setup_root(struct cgroup_root *root, unsigned long ss_mask) */ ret = allocate_cgrp_cset_links(css_set_count, &tmp_links); if (ret) - goto out; + goto cancel_ref; ret = cgroup_init_root_id(root); if (ret) - goto out; + goto cancel_ref; root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops, KERNFS_ROOT_CREATE_DEACTIVATED, @@ -1463,7 +1625,7 @@ static int cgroup_setup_root(struct cgroup_root *root, unsigned long ss_mask) link_css_set(&tmp_links, cset, root_cgrp); up_write(&css_set_rwsem); - BUG_ON(!list_empty(&root_cgrp->children)); + BUG_ON(!list_empty(&root_cgrp->self.children)); BUG_ON(atomic_read(&root->nr_cgrps) != 1); kernfs_activate(root_cgrp->kn); @@ -1475,6 +1637,8 @@ destroy_root: root->kf_root = NULL; exit_root_id: cgroup_exit_root_id(root); +cancel_ref: + percpu_ref_cancel_init(&root_cgrp->self.refcnt); out: free_cgrp_cset_links(&tmp_links); return ret; @@ -1497,14 +1661,13 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, if (!use_task_css_set_links) cgroup_enable_task_cg_lists(); - mutex_lock(&cgroup_tree_mutex); mutex_lock(&cgroup_mutex); /* First find the desired set of subsystems */ ret = parse_cgroupfs_options(data, &opts); if (ret) goto out_unlock; -retry: + /* look for a matching existing root */ if (!opts.subsys_mask && !opts.none && !opts.name) { cgrp_dfl_root_visible = true; @@ -1536,7 +1699,7 @@ retry: * subsystems) then they must match. */ if ((opts.subsys_mask || opts.none) && - (opts.subsys_mask != root->cgrp.subsys_mask)) { + (opts.subsys_mask != root->subsys_mask)) { if (!name_match) continue; ret = -EBUSY; @@ -1545,28 +1708,27 @@ retry: 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"); + pr_err("sane_behavior: new mount options should match the existing superblock\n"); ret = -EINVAL; goto out_unlock; } else { - pr_warning("cgroup: new mount options do not match the existing superblock, will be ignored\n"); + pr_warn("new mount options do not match the existing superblock, will be ignored\n"); } } /* - * A root's lifetime is governed by its root cgroup. Zero - * ref indicate that the root is being destroyed. Wait for - * destruction to complete so that the subsystems are free. - * We can use wait_queue for the wait but this path is - * super cold. Let's just sleep for a bit and retry. + * A root's lifetime is governed by its root cgroup. + * tryget_live failure indicate that the root is being + * destroyed. Wait for destruction to complete so that the + * subsystems are free. We can use wait_queue for the wait + * but this path is super cold. Let's just sleep for a bit + * and retry. */ - if (!atomic_inc_not_zero(&root->cgrp.refcnt)) { + if (!percpu_ref_tryget_live(&root->cgrp.self.refcnt)) { mutex_unlock(&cgroup_mutex); - mutex_unlock(&cgroup_tree_mutex); msleep(10); - mutex_lock(&cgroup_tree_mutex); - mutex_lock(&cgroup_mutex); - goto retry; + ret = restart_syscall(); + goto out_free; } ret = 0; @@ -1597,8 +1759,7 @@ retry: out_unlock: mutex_unlock(&cgroup_mutex); - mutex_unlock(&cgroup_tree_mutex); - +out_free: kfree(opts.release_agent); |