diff options
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 67 |
1 files changed, 8 insertions, 59 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 5068216..9df799d 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4341,47 +4341,6 @@ static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) return cgroup_create(c_parent, dentry, mode | S_IFDIR); } -/* - * Check the reference count on each subsystem. Since we already - * established that there are no tasks in the cgroup, if the css refcount - * is also 1, then there should be no outstanding references, so the - * subsystem is safe to destroy. We scan across all subsystems rather than - * using the per-hierarchy linked list of mounted subsystems since we can - * be called via check_for_release() with no synchronization other than - * RCU, and the subsystem linked list isn't RCU-safe. - */ -static int cgroup_has_css_refs(struct cgroup *cgrp) -{ - int i; - - /* - * We won't need to lock the subsys array, because the subsystems - * we're concerned about aren't going anywhere since our cgroup root - * has a reference on them. - */ - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { - struct cgroup_subsys *ss = subsys[i]; - struct cgroup_subsys_state *css; - - /* Skip subsystems not present or not in this hierarchy */ - if (ss == NULL || ss->root != cgrp->root) - continue; - - css = cgrp->subsys[ss->subsys_id]; - /* - * When called from check_for_release() it's possible - * that by this point the cgroup has been removed - * and the css deleted. But a false-positive doesn't - * matter, since it can only happen if the cgroup - * has been deleted and hence no longer needs the - * release agent to be called anyway. - */ - if (css && css_refcnt(css) > 1) - return 1; - } - return 0; -} - static int cgroup_destroy_locked(struct cgroup *cgrp) __releases(&cgroup_mutex) __acquires(&cgroup_mutex) { @@ -5108,12 +5067,15 @@ static void check_for_release(struct cgroup *cgrp) { /* All of these checks rely on RCU to keep the cgroup * structure alive */ - if (cgroup_is_releasable(cgrp) && !atomic_read(&cgrp->count) - && list_empty(&cgrp->children) && !cgroup_has_css_refs(cgrp)) { - /* Control Group is currently removeable. If it's not + if (cgroup_is_releasable(cgrp) && + !atomic_read(&cgrp->count) && list_empty(&cgrp->children)) { + /* + * Control Group is currently removeable. If it's not * already queued for a userspace notification, queue - * it now */ + * it now + */ int need_schedule_work = 0; + raw_spin_lock(&release_list_lock); if (!cgroup_is_removed(cgrp) && list_empty(&cgrp->release_list)) { @@ -5146,24 +5108,11 @@ EXPORT_SYMBOL_GPL(__css_tryget); /* Caller must verify that the css is not for root cgroup */ void __css_put(struct cgroup_subsys_state *css) { - struct cgroup *cgrp = css->cgroup; int v; - rcu_read_lock(); v = css_unbias_refcnt(atomic_dec_return(&css->refcnt)); - - switch (v) { - case 1: - if (notify_on_release(cgrp)) { - set_bit(CGRP_RELEASABLE, &cgrp->flags); - check_for_release(cgrp); - } - break; - case 0: + if (v == 0) schedule_work(&css->dput_work); - break; - } - rcu_read_unlock(); } EXPORT_SYMBOL_GPL(__css_put); |