diff options
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r-- | kernel/cgroup.c | 325 |
1 files changed, 179 insertions, 146 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 4855892..a32f943 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -52,7 +52,7 @@ #include <linux/module.h> #include <linux/delayacct.h> #include <linux/cgroupstats.h> -#include <linux/hash.h> +#include <linux/hashtable.h> #include <linux/namei.h> #include <linux/pid_namespace.h> #include <linux/idr.h> @@ -376,22 +376,18 @@ static int css_set_count; * account cgroups in empty hierarchies. */ #define CSS_SET_HASH_BITS 7 -#define CSS_SET_TABLE_SIZE (1 << CSS_SET_HASH_BITS) -static struct hlist_head css_set_table[CSS_SET_TABLE_SIZE]; +static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS); -static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[]) +static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) { int i; - int index; - unsigned long tmp = 0UL; + unsigned long key = 0UL; for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) - tmp += (unsigned long)css[i]; - tmp = (tmp >> 16) ^ tmp; + key += (unsigned long)css[i]; + key = (key >> 16) ^ key; - index = hash_long(tmp, CSS_SET_HASH_BITS); - - return &css_set_table[index]; + return key; } /* We don't maintain the lists running through each css_set to its @@ -418,7 +414,7 @@ static void __put_css_set(struct css_set *cg, int taskexit) } /* This css_set is dead. unlink it and release cgroup refcounts */ - hlist_del(&cg->hlist); + hash_del(&cg->hlist); css_set_count--; list_for_each_entry_safe(link, saved_link, &cg->cg_links, @@ -426,12 +422,20 @@ static void __put_css_set(struct css_set *cg, int taskexit) struct cgroup *cgrp = link->cgrp; list_del(&link->cg_link_list); list_del(&link->cgrp_link_list); + + /* + * We may not be holding cgroup_mutex, and if cgrp->count is + * dropped to 0 the cgroup can be destroyed at any time, hence + * rcu_read_lock is used to keep it alive. + */ + rcu_read_lock(); if (atomic_dec_and_test(&cgrp->count) && notify_on_release(cgrp)) { if (taskexit) set_bit(CGRP_RELEASABLE, &cgrp->flags); check_for_release(cgrp); } + rcu_read_unlock(); kfree(link); } @@ -550,9 +554,8 @@ static struct css_set *find_existing_css_set( { int i; struct cgroupfs_root *root = cgrp->root; - struct hlist_head *hhead; - struct hlist_node *node; struct css_set *cg; + unsigned long key; /* * Build the set of subsystem state objects that we want to see in the @@ -572,8 +575,8 @@ static struct css_set *find_existing_css_set( } } - hhead = css_set_hash(template); - hlist_for_each_entry(cg, node, hhead, hlist) { + key = css_set_hash(template); + hash_for_each_possible(css_set_table, cg, hlist, key) { if (!compare_css_sets(cg, oldcg, cgrp, template)) continue; @@ -657,8 +660,8 @@ static struct css_set *find_css_set( struct list_head tmp_cg_links; - struct hlist_head *hhead; struct cg_cgroup_link *link; + unsigned long key; /* First see if we already have a cgroup group that matches * the desired set */ @@ -704,8 +707,8 @@ static struct css_set *find_css_set( css_set_count++; /* Add this cgroup group to the hash table */ - hhead = css_set_hash(res->subsys); - hlist_add_head(&res->hlist, hhead); + key = css_set_hash(res->subsys); + hash_add(css_set_table, &res->hlist, key); write_unlock(&css_set_lock); @@ -856,47 +859,54 @@ static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb) return inode; } -static void cgroup_diput(struct dentry *dentry, struct inode *inode) +static void cgroup_free_fn(struct work_struct *work) { - /* is dentry a directory ? if so, kfree() associated cgroup */ - if (S_ISDIR(inode->i_mode)) { - struct cgroup *cgrp = dentry->d_fsdata; - struct cgroup_subsys *ss; - BUG_ON(!(cgroup_is_removed(cgrp))); - /* It's possible for external users to be holding css - * reference counts on a cgroup; css_put() needs to - * be able to access the cgroup after decrementing - * the reference count in order to know if it needs to - * queue the cgroup to be handled by the release - * agent */ - synchronize_rcu(); + struct cgroup *cgrp = container_of(work, struct cgroup, free_work); + struct cgroup_subsys *ss; - mutex_lock(&cgroup_mutex); - /* - * Release the subsystem state objects. - */ - for_each_subsys(cgrp->root, ss) - ss->css_free(cgrp); + mutex_lock(&cgroup_mutex); + /* + * Release the subsystem state objects. + */ + for_each_subsys(cgrp->root, ss) + ss->css_free(cgrp); - cgrp->root->number_of_cgroups--; - mutex_unlock(&cgroup_mutex); + cgrp->root->number_of_cgroups--; + mutex_unlock(&cgroup_mutex); - /* - * Drop the active superblock reference that we took when we - * created the cgroup - */ - deactivate_super(cgrp->root->sb); + /* + * Drop the active superblock reference that we took when we + * created the cgroup + */ + deactivate_super(cgrp->root->sb); - /* - * if we're getting rid of the cgroup, refcount should ensure - * that there are no pidlists left. - */ - BUG_ON(!list_empty(&cgrp->pidlists)); + /* + * if we're getting rid of the cgroup, refcount should ensure + * that there are no pidlists left. + */ + BUG_ON(!list_empty(&cgrp->pidlists)); + + simple_xattrs_free(&cgrp->xattrs); + + ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id); + kfree(cgrp); +} - simple_xattrs_free(&cgrp->xattrs); +static void cgroup_free_rcu(struct rcu_head *head) +{ + struct cgroup *cgrp = container_of(head, struct cgroup, rcu_head); + + schedule_work(&cgrp->free_work); +} + +static void cgroup_diput(struct dentry *dentry, struct inode *inode) +{ + /* is dentry a directory ? if so, kfree() associated cgroup */ + if (S_ISDIR(inode->i_mode)) { + struct cgroup *cgrp = dentry->d_fsdata; - ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id); - kfree_rcu(cgrp, rcu_head); + BUG_ON(!(cgroup_is_removed(cgrp))); + call_rcu(&cgrp->rcu_head, cgroup_free_rcu); } else { struct cfent *cfe = __d_cfe(dentry); struct cgroup *cgrp = dentry->d_parent->d_fsdata; @@ -925,13 +935,17 @@ static void remove_dir(struct dentry *d) dput(parent); } -static int cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) +static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) { struct cfent *cfe; lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex); lockdep_assert_held(&cgroup_mutex); + /* + * If we're doing cleanup due to failure of cgroup_create(), + * the corresponding @cfe may not exist. + */ list_for_each_entry(cfe, &cgrp->files, node) { struct dentry *d = cfe->dentry; @@ -944,9 +958,8 @@ static int cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) list_del_init(&cfe->node); dput(d); - return 0; + break; } - return -ENOENT; } /** @@ -1083,7 +1096,6 @@ static int rebind_subsystems(struct cgroupfs_root *root, } } root->subsys_mask = root->actual_subsys_mask = final_subsys_mask; - synchronize_rcu(); return 0; } @@ -1393,6 +1405,7 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp) INIT_LIST_HEAD(&cgrp->allcg_node); INIT_LIST_HEAD(&cgrp->release_list); INIT_LIST_HEAD(&cgrp->pidlists); + INIT_WORK(&cgrp->free_work, cgroup_free_fn); mutex_init(&cgrp->pidlist_mutex); INIT_LIST_HEAD(&cgrp->event_list); spin_lock_init(&cgrp->event_list_lock); @@ -1597,6 +1610,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, struct cgroupfs_root *existing_root; const struct cred *cred; int i; + struct css_set *cg; BUG_ON(sb->s_root != NULL); @@ -1650,14 +1664,8 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, /* Link the top cgroup in this hierarchy into all * the css_set objects */ write_lock(&css_set_lock); - for (i = 0; i < CSS_SET_TABLE_SIZE; i++) { - struct hlist_head *hhead = &css_set_table[i]; - struct hlist_node *node; - struct css_set *cg; - - hlist_for_each_entry(cg, node, hhead, hlist) - link_css_set(&tmp_cg_links, cg, root_cgrp); - } + hash_for_each(css_set_table, i, cg, hlist) + link_css_set(&tmp_cg_links, cg, root_cgrp); write_unlock(&css_set_lock); free_cg_links(&tmp_cg_links); @@ -1773,7 +1781,7 @@ int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) rcu_lockdep_assert(rcu_read_lock_held() || cgroup_lock_is_held(), "cgroup_path() called without proper locking"); - if (!dentry || cgrp == dummytop) { + if (cgrp == dummytop) { /* * Inactive subsystems have no dentry for their root * cgroup @@ -1982,7 +1990,6 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) ss->attach(cgrp, &tset); } - synchronize_rcu(); out: if (retval) { for_each_subsys(root, ss) { @@ -2151,7 +2158,6 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) /* * step 5: success! and cleanup */ - synchronize_rcu(); retval = 0; out_put_css_set_refs: if (retval) { @@ -2637,7 +2643,7 @@ static struct dentry *cgroup_lookup(struct inode *dir, struct dentry *dentry, un */ static inline struct cftype *__file_cft(struct file *file) { - if (file->f_dentry->d_inode->i_fop != &cgroup_file_operations) + if (file_inode(file)->i_fop != &cgroup_file_operations) return ERR_PTR(-EINVAL); return __d_cft(file->f_dentry); } @@ -2769,14 +2775,14 @@ static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys, if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent) continue; - if (is_add) + if (is_add) { err = cgroup_add_file(cgrp, subsys, cft); - else - err = cgroup_rm_file(cgrp, cft); - if (err) { - pr_warning("cgroup_addrm_files: failed to %s %s, err=%d\n", - is_add ? "add" : "remove", cft->name, err); + if (err) + pr_warn("cgroup_addrm_files: failed to add %s, err=%d\n", + cft->name, err); ret = err; + } else { + cgroup_rm_file(cgrp, cft); } } return ret; @@ -3017,6 +3023,32 @@ struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos, } EXPORT_SYMBOL_GPL(cgroup_next_descendant_pre); +/** + * cgroup_rightmost_descendant - return the rightmost descendant of a cgroup + * @pos: cgroup of interest + * + * Return the rightmost descendant of @pos. If there's no descendant, + * @pos is returned. This can be used during pre-order traversal to skip + * subtree of @pos. + */ +struct cgroup *cgroup_rightmost_descendant(struct cgroup *pos) +{ + struct cgroup *last, *tmp; + + WARN_ON_ONCE(!rcu_read_lock_held()); + + do { + last = pos; + /* ->prev isn't RCU safe, walk ->next till the end */ + pos = NULL; + list_for_each_entry_rcu(tmp, &last->children, sibling) + pos = tmp; + } while (pos); + + return last; +} +EXPORT_SYMBOL_GPL(cgroup_rightmost_descendant); + static struct cgroup *cgroup_leftmost_descendant(struct cgroup *pos) { struct cgroup *last; @@ -3752,8 +3784,13 @@ static void cgroup_event_remove(struct work_struct *work) remove); struct cgroup *cgrp = event->cgrp; + remove_wait_queue(event->wqh, &event->wait); + event->cft->unregister_event(cgrp, event->cft, event->eventfd); + /* Notify userspace the event is going away. */ + eventfd_signal(event->eventfd, 1); + eventfd_ctx_put(event->eventfd); kfree(event); dput(cgrp->dentry); @@ -3773,15 +3810,25 @@ static int cgroup_event_wake(wait_queue_t *wait, unsigned mode, unsigned long flags = (unsigned long)key; if (flags & POLLHUP) { - __remove_wait_queue(event->wqh, &event->wait); - spin_lock(&cgrp->event_list_lock); - list_del_init(&event->list); - spin_unlock(&cgrp->event_list_lock); /* - * We are in atomic context, but cgroup_event_remove() may - * sleep, so we have to call it in workqueue. + * If the event has been detached at cgroup removal, we + * can simply return knowing the other side will cleanup + * for us. + * + * We can't race against event freeing since the other + * side will require wqh->lock via remove_wait_queue(), + * which we hold. */ - schedule_work(&event->remove); + spin_lock(&cgrp->event_list_lock); + if (!list_empty(&event->list)) { + list_del_init(&event->list); + /* + * We are in atomic context, but cgroup_event_remove() + * may sleep, so we have to call it in workqueue. + */ + schedule_work(&event->remove); + } + spin_unlock(&cgrp->event_list_lock); } return 0; @@ -3807,6 +3854,7 @@ static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft, const char *buffer) { struct cgroup_event *event = NULL; + struct cgroup *cgrp_cfile; unsigned int efd, cfd; struct file *efile = NULL; struct file *cfile = NULL; @@ -3852,7 +3900,7 @@ static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft, /* the process need read permission on control file */ /* AV: shouldn't we check that it's been opened for read instead? */ - ret = inode_permission(cfile->f_path.dentry->d_inode, MAY_READ); + ret = inode_permission(file_inode(cfile), MAY_READ); if (ret < 0) goto fail; @@ -3862,6 +3910,16 @@ static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft, goto fail; } + /* + * The file to be monitored must be in the same cgroup as + * cgroup.event_control is. + */ + cgrp_cfile = __d_cgrp(cfile->f_dentry->d_parent); + if (cgrp_cfile != cgrp) { + ret = -EINVAL; + goto fail; + } + if (!event->cft->register_event || !event->cft->unregister_event) { ret = -EINVAL; goto fail; @@ -4135,6 +4193,9 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, init_cgroup_housekeeping(cgrp); + dentry->d_fsdata = cgrp; + cgrp->dentry = dentry; + cgrp->parent = parent; cgrp->root = parent->root; cgrp->top_cgroup = parent->top_cgroup; @@ -4172,8 +4233,6 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, 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++; @@ -4340,20 +4399,14 @@ static int cgroup_destroy_locked(struct cgroup *cgrp) /* * Unregister events and notify userspace. * Notify userspace about cgroup removing only after rmdir of cgroup - * 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. + * directory to avoid race between userspace and kernelspace. */ spin_lock(&cgrp->event_list_lock); - 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_for_each_entry_safe(event, tmp, &cgrp->event_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); return 0; } @@ -4438,6 +4491,9 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) { struct cgroup_subsys_state *css; int i, ret; + struct hlist_node *tmp; + struct css_set *cg; + unsigned long key; /* check name and function validity */ if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN || @@ -4503,23 +4559,17 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) * this is all done under the css_set_lock. */ write_lock(&css_set_lock); - for (i = 0; i < CSS_SET_TABLE_SIZE; i++) { - struct css_set *cg; - struct hlist_node *node, *tmp; - struct hlist_head *bucket = &css_set_table[i], *new_bucket; - - hlist_for_each_entry_safe(cg, node, tmp, bucket, hlist) { - /* skip entries that we already rehashed */ - if (cg->subsys[ss->subsys_id]) - continue; - /* remove existing entry */ - hlist_del(&cg->hlist); - /* set new value */ - cg->subsys[ss->subsys_id] = css; - /* recompute hash and restore entry */ - new_bucket = css_set_hash(cg->subsys); - hlist_add_head(&cg->hlist, new_bucket); - } + hash_for_each_safe(css_set_table, i, tmp, cg, hlist) { + /* skip entries that we already rehashed */ + if (cg->subsys[ss->subsys_id]) + continue; + /* remove existing entry */ + hash_del(&cg->hlist); + /* set new value */ + cg->subsys[ss->subsys_id] = css; + /* recompute hash and restore entry */ + key = css_set_hash(cg->subsys); + hash_add(css_set_table, &cg->hlist, key); } write_unlock(&css_set_lock); @@ -4551,7 +4601,6 @@ EXPORT_SYMBOL_GPL(cgroup_load_subsys); void cgroup_unload_subsys(struct cgroup_subsys *ss) { struct cg_cgroup_link *link; - struct hlist_head *hhead; BUG_ON(ss->module == NULL); @@ -4567,10 +4616,8 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) offline_css(ss, dummytop); ss->active = 0; - if (ss->use_id) { - idr_remove_all(&ss->idr); + if (ss->use_id) idr_destroy(&ss->idr); - } /* deassign the subsys_id */ subsys[ss->subsys_id] = NULL; @@ -4585,11 +4632,12 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) write_lock(&css_set_lock); list_for_each_entry(link, &dummytop->css_sets, cgrp_link_list) { struct css_set *cg = link->cg; + unsigned long key; - hlist_del(&cg->hlist); + hash_del(&cg->hlist); cg->subsys[ss->subsys_id] = NULL; - hhead = css_set_hash(cg->subsys); - hlist_add_head(&cg->hlist, hhead); + key = css_set_hash(cg->subsys); + hash_add(css_set_table, &cg->hlist, key); } write_unlock(&css_set_lock); @@ -4631,9 +4679,6 @@ int __init cgroup_init_early(void) list_add(&init_css_set_link.cg_link_list, &init_css_set.cg_links); - for (i = 0; i < CSS_SET_TABLE_SIZE; i++) - INIT_HLIST_HEAD(&css_set_table[i]); - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { struct cgroup_subsys *ss = subsys[i]; @@ -4667,7 +4712,7 @@ int __init cgroup_init(void) { int err; int i; - struct hlist_head *hhead; + unsigned long key; err = bdi_init(&cgroup_backing_dev_info); if (err) @@ -4686,8 +4731,8 @@ int __init cgroup_init(void) } /* Add init_css_set to the hash table */ - hhead = css_set_hash(init_css_set.subsys); - hlist_add_head(&init_css_set.hlist, hhead); + key = css_set_hash(init_css_set.subsys); + hash_add(css_set_table, &init_css_set.hlist, key); BUG_ON(!init_root_id(&rootnode)); cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj); @@ -4982,8 +5027,7 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks) } task_unlock(tsk); - if (cg) - put_css_set_taskexit(cg); + put_css_set_taskexit(cg); } /** @@ -5274,7 +5318,7 @@ EXPORT_SYMBOL_GPL(free_css_id); static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth) { struct css_id *newid; - int myid, error, size; + int ret, size; BUG_ON(!ss->use_id); @@ -5282,35 +5326,24 @@ static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth) newid = kzalloc(size, GFP_KERNEL); if (!newid) return ERR_PTR(-ENOMEM); - /* get id */ - if (unlikely(!idr_pre_get(&ss->idr, GFP_KERNEL))) { - error = -ENOMEM; - goto err_out; - } + + idr_preload(GFP_KERNEL); spin_lock(&ss->id_lock); /* Don't use 0. allocates an ID of 1-65535 */ - error = idr_get_new_above(&ss->idr, newid, 1, &myid); + ret = idr_alloc(&ss->idr, newid, 1, CSS_ID_MAX + 1, GFP_NOWAIT); spin_unlock(&ss->id_lock); + idr_preload_end(); /* Returns error when there are no free spaces for new ID.*/ - if (error) { - error = -ENOSPC; + if (ret < 0) goto err_out; - } - if (myid > CSS_ID_MAX) - goto remove_idr; - newid->id = myid; + newid->id = ret; newid->depth = depth; return newid; -remove_idr: - error = -ENOSPC; - spin_lock(&ss->id_lock); - idr_remove(&ss->idr, myid); - spin_unlock(&ss->id_lock); err_out: kfree(newid); - return ERR_PTR(error); + return ERR_PTR(ret); } @@ -5441,7 +5474,7 @@ struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id) struct inode *inode; struct cgroup_subsys_state *css; - inode = f->f_dentry->d_inode; + inode = file_inode(f); /* check in cgroup filesystem dir */ if (inode->i_op != &cgroup_dir_inode_operations) return ERR_PTR(-EBADF); |