diff options
| -rw-r--r-- | kernel/cgroup.c | 51 |
1 files changed, 43 insertions, 8 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 3fa0463e74bb..7cb9c0847445 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -100,6 +100,12 @@ static DECLARE_RWSEM(css_set_rwsem); #endif /* + * Protects cgroup_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. */ @@ -190,6 +196,37 @@ 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(&cgroup_idr_lock); + ret = idr_alloc(idr, ptr, start, end, gfp_mask); + spin_unlock(&cgroup_idr_lock); + idr_preload_end(); + return ret; +} + +static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id) +{ + void *ret; + + spin_lock(&cgroup_idr_lock); + ret = idr_replace(idr, ptr, id); + spin_unlock(&cgroup_idr_lock); + return ret; +} + +static void cgroup_idr_remove(struct idr *idr, int id) +{ + spin_lock(&cgroup_idr_lock); + idr_remove(idr, id); + spin_unlock(&cgroup_idr_lock); +} + /** * cgroup_css - obtain a cgroup's css for the specified subsystem * @cgrp: the cgroup of interest @@ -1058,9 +1095,7 @@ static void cgroup_put(struct cgroup *cgrp) * per-subsystem and moved to css->id so that lookups are * successful until the target css is released. */ - mutex_lock(&cgroup_mutex); - idr_remove(&cgrp->root->cgroup_idr, cgrp->id); - mutex_unlock(&cgroup_mutex); + cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id); cgrp->id = -1; call_rcu(&cgrp->rcu_head, cgroup_free_rcu); @@ -1531,7 +1566,7 @@ static int cgroup_setup_root(struct cgroup_root *root, unsigned int ss_mask) lockdep_assert_held(&cgroup_tree_mutex); lockdep_assert_held(&cgroup_mutex); - ret = idr_alloc(&root->cgroup_idr, root_cgrp, 1, 2, GFP_KERNEL); + ret = cgroup_idr_alloc(&root->cgroup_idr, root_cgrp, 1, 2, GFP_NOWAIT); if (ret < 0) goto out; root_cgrp->id = ret; @@ -4225,7 +4260,7 @@ static long cgroup_create(struct cgroup *parent, const char *name, * Temporarily set the pointer to NULL, so idr_find() won't return * a half-baked cgroup. */ - cgrp->id = idr_alloc(&root->cgroup_idr, NULL, 2, 0, GFP_KERNEL); + cgrp->id = cgroup_idr_alloc(&root->cgroup_idr, NULL, 2, 0, GFP_NOWAIT); if (cgrp->id < 0) { err = -ENOMEM; goto err_unlock; @@ -4268,7 +4303,7 @@ static long cgroup_create(struct cgroup *parent, const char *name, * @cgrp is now fully operational. If something fails after this * point, it'll be released via the normal destruction path. */ - idr_replace(&root->cgroup_idr, cgrp, cgrp->id); + cgroup_idr_replace(&root->cgroup_idr, cgrp, cgrp->id); err = cgroup_kn_set_ugid(kn); if (err) @@ -4302,7 +4337,7 @@ static long cgroup_create(struct cgroup *parent, const char *name, return 0; err_free_id: - idr_remove(&root->cgroup_idr, cgrp->id); + cgroup_idr_remove(&root->cgroup_idr, cgrp->id); err_unlock: mutex_unlock(&cgroup_mutex); err_unlock_tree: @@ -5162,7 +5197,7 @@ struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss) { struct cgroup *cgrp; - cgroup_assert_mutexes_or_rcu_locked(); + WARN_ON_ONCE(!rcu_read_lock_held()); cgrp = idr_find(&ss->root->cgroup_idr, id); if (cgrp) |