cgroup: convert cgroup_has_live_children() into css_has_online_children()
Now that cgroup liveliness and css onliness are the same state,
convert cgroup_has_live_children() into css_has_online_children() so
that it can be used for actual csses too. The function now uses
css_for_each_child() for iteration and is published.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 004004f..082bb84 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -175,7 +175,6 @@
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 @@
* 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 @@
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 @@
* ->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 @@
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
