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-rw-r--r--kernel/cgroup.c52
1 files changed, 24 insertions, 28 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 174f4c3..3c4c4b0 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4355,6 +4355,7 @@ static void offline_css(struct cgroup_subsys_state *css)
ss->css_offline(css);
css->flags &= ~CSS_ONLINE;
+ css->cgroup->nr_css--;
}
/*
@@ -4559,14 +4560,29 @@ static void css_killed_work_fn(struct work_struct *work)
mutex_lock(&cgroup_mutex);
/*
+ * css_tryget() is guaranteed to fail now. Tell subsystems to
+ * initate destruction.
+ */
+ offline_css(css);
+
+ /*
* If @cgrp is marked dead, it's waiting for refs of all css's to
* be disabled before proceeding to the second phase of cgroup
* destruction. If we are the last one, kick it off.
*/
- if (!--cgrp->nr_css && cgroup_is_dead(cgrp))
+ if (!cgrp->nr_css && cgroup_is_dead(cgrp))
cgroup_destroy_css_killed(cgrp);
mutex_unlock(&cgroup_mutex);
+
+ /*
+ * Put the css refs from kill_css(). Each css holds an extra
+ * reference to the cgroup's dentry and cgroup removal proceeds
+ * regardless of css refs. On the last put of each css, whenever
+ * that may be, the extra dentry ref is put so that dentry
+ * destruction happens only after all css's are released.
+ */
+ css_put(css);
}
/* css kill confirmation processing requires process context, bounce */
@@ -4633,11 +4649,10 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
* as killed on all CPUs on return.
*
* Use percpu_ref_kill_and_confirm() to get notifications as each
- * css is confirmed to be seen as killed on all CPUs. The
- * notification callback keeps track of the number of css's to be
- * killed and invokes cgroup_destroy_css_killed() to perform the
- * rest of destruction once the percpu refs of all css's are
- * confirmed to be killed.
+ * css is confirmed to be seen as killed on all CPUs.
+ * cgroup_destroy_css_killed() will be invoked to perform the rest
+ * of destruction once the percpu refs of all css's are confirmed
+ * to be killed.
*/
for_each_root_subsys(cgrp->root, ss) {
struct cgroup_subsys_state *css = cgroup_css(cgrp, ss->subsys_id);
@@ -4704,36 +4719,17 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
* @work: cgroup->destroy_free_work
*
* This function is invoked from a work item for a cgroup which is being
- * destroyed after the percpu refcnts of all css's are guaranteed to be
- * seen as killed on all CPUs, and performs the rest of destruction. This
- * is the second step of destruction described in the comment above
- * cgroup_destroy_locked().
+ * destroyed after all css's are offlined and performs the rest of
+ * destruction. This is the second step of destruction described in the
+ * comment above cgroup_destroy_locked().
*/
static void cgroup_destroy_css_killed(struct cgroup *cgrp)
{
struct cgroup *parent = cgrp->parent;
struct dentry *d = cgrp->dentry;
- struct cgroup_subsys *ss;
lockdep_assert_held(&cgroup_mutex);
- /*
- * css_tryget() is guaranteed to fail now. Tell subsystems to
- * initate destruction.
- */
- for_each_root_subsys(cgrp->root, ss)
- offline_css(cgroup_css(cgrp, ss->subsys_id));
-
- /*
- * Put the css refs from cgroup_destroy_locked(). Each css holds
- * an extra reference to the cgroup's dentry and cgroup removal
- * proceeds regardless of css refs. On the last put of each css,
- * whenever that may be, the extra dentry ref is put so that dentry
- * destruction happens only after all css's are released.
- */
- for_each_root_subsys(cgrp->root, ss)
- css_put(cgroup_css(cgrp, ss->subsys_id));
-
/* delete this cgroup from parent->children */
list_del_rcu(&cgrp->sibling);
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