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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>
This commit is contained in:
Tejun Heo 2014-05-16 13:22:52 -04:00
parent 184faf3232
commit f3d4650015
2 changed files with 22 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/cgroup.h
View File

@ -873,6 +873,8 @@ css_next_descendant_post(struct cgroup_subsys_state *pos,
for ((pos) = css_next_descendant_post(NULL, (css)); (pos); \ for ((pos) = css_next_descendant_post(NULL, (css)); (pos); \
(pos) = css_next_descendant_post((pos), (css))) (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 */ /* A css_task_iter should be treated as an opaque object */
struct css_task_iter { struct css_task_iter {
struct cgroup_subsys *ss; struct cgroup_subsys *ss;

32
kernel/cgroup.c
View File

@ -175,7 +175,6 @@ static int need_forkexit_callback __read_mostly;
static struct cftype cgroup_base_files[]; static struct cftype cgroup_base_files[];
static void cgroup_put(struct cgroup *cgrp); 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, static int rebind_subsystems(struct cgroup_root *dst_root,
unsigned int ss_mask); unsigned int ss_mask);
static int cgroup_destroy_locked(struct cgroup *cgrp); 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(). * This prevents new mounts by disabling percpu_ref_tryget_live().
* cgroup_mount() may wait for @root's release. * 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); cgroup_put(&root->cgrp);
else else
percpu_ref_kill(&root->cgrp.self.refcnt); percpu_ref_kill(&root->cgrp.self.refcnt);
@ -3291,19 +3290,28 @@ css_next_descendant_post(struct cgroup_subsys_state *pos,
return pos->parent; 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(); rcu_read_lock();
list_for_each_entry_rcu(child, &cgrp->self.children, self.sibling) { css_for_each_child(child, css) {
if (!cgroup_is_dead(child)) { if (css->flags & CSS_ONLINE) {
rcu_read_unlock(); ret = true;
return true; break;
} }
} }
rcu_read_unlock(); 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 * ->self.children as dead children linger on it while being
* drained; otherwise, "rmdir parent/child parent" may fail. * drained; otherwise, "rmdir parent/child parent" may fail.
*/ */
if (cgroup_has_live_children(cgrp)) if (css_has_online_children(&cgrp->self))
return -EBUSY; return -EBUSY;
/* /*
@ -5014,8 +5022,8 @@ void cgroup_exit(struct task_struct *tsk)
static void check_for_release(struct cgroup *cgrp) static void check_for_release(struct cgroup *cgrp)
{ {
if (cgroup_is_releasable(cgrp) && if (cgroup_is_releasable(cgrp) && list_empty(&cgrp->cset_links) &&
list_empty(&cgrp->cset_links) && !cgroup_has_live_children(cgrp)) { !css_has_online_children(&cgrp->self)) {
/* /*
* Control Group is currently removeable. If it's not * Control Group is currently removeable. If it's not
* already queued for a userspace notification, queue * already queued for a userspace notification, queue