diff options
| -rw-r--r-- | include/linux/cgroup.h | 2 | ||||
| -rw-r--r-- | kernel/cgroup.c | 32 |
2 files changed, 22 insertions, 12 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 51a339c99eb6..b76999954beb 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -873,6 +873,8 @@ css_next_descendant_post(struct cgroup_subsys_state *pos, for ((pos) = css_next_descendant_post(NULL, (css)); (pos); \ (pos) = css_next_descendant_post((pos), (css))) +bool css_has_online_children(struct cgroup_subsys_state *css); + /* A css_task_iter should be treated as an opaque object */ struct css_task_iter { struct cgroup_subsys *ss; diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 004004fd0ded..082bb842b11a 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -175,7 +175,6 @@ static int need_forkexit_callback __read_mostly; static struct cftype cgroup_base_files[]; static void cgroup_put(struct cgroup *cgrp); -static bool cgroup_has_live_children(struct cgroup *cgrp); static int rebind_subsystems(struct cgroup_root *dst_root, unsigned int ss_mask); static int cgroup_destroy_locked(struct cgroup *cgrp); @@ -1769,7 +1768,7 @@ static void cgroup_kill_sb(struct super_block *sb) * This prevents new mounts by disabling percpu_ref_tryget_live(). * cgroup_mount() may wait for @root's release. */ - if (cgroup_has_live_children(&root->cgrp)) + if (css_has_online_children(&root->cgrp.self)) cgroup_put(&root->cgrp); else percpu_ref_kill(&root->cgrp.self.refcnt); @@ -3291,19 +3290,28 @@ css_next_descendant_post(struct cgroup_subsys_state *pos, return pos->parent; } -static bool cgroup_has_live_children(struct cgroup *cgrp) +/** + * css_has_online_children - does a css have online children + * @css: the target css + * + * Returns %true if @css has any online children; otherwise, %false. This + * function can be called from any context but the caller is responsible + * for synchronizing against on/offlining as necessary. + */ +bool css_has_online_children(struct cgroup_subsys_state *css) { - struct cgroup *child; + struct cgroup_subsys_state *child; + bool ret = false; rcu_read_lock(); - list_for_each_entry_rcu(child, &cgrp->self.children, self.sibling) { - if (!cgroup_is_dead(child)) { - rcu_read_unlock(); - return true; + css_for_each_child(child, css) { + if (css->flags & CSS_ONLINE) { + ret = true; + break; } } rcu_read_unlock(); - return false; + return ret; } /** @@ -4535,7 +4543,7 @@ static int cgroup_destroy_locked(struct cgroup *cgrp) * ->self.children as dead children linger on it while being * drained; otherwise, "rmdir parent/child parent" may fail. */ - if (cgroup_has_live_children(cgrp)) + if (css_has_online_children(&cgrp->self)) return -EBUSY; /* @@ -5014,8 +5022,8 @@ void cgroup_exit(struct task_struct *tsk) static void check_for_release(struct cgroup *cgrp) { - if (cgroup_is_releasable(cgrp) && - list_empty(&cgrp->cset_links) && !cgroup_has_live_children(cgrp)) { + if (cgroup_is_releasable(cgrp) && list_empty(&cgrp->cset_links) && + !css_has_online_children(&cgrp->self)) { /* * Control Group is currently removeable. If it's not * already queued for a userspace notification, queue |