Add a new cgroup subsys callback css_released(). This is called when
the reference count of the css (cgroup_subsys_state) reaches zero
before RCU scheduling free.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: Li Zefan <lizefan@xxxxxxxxxx>
---
include/linux/cgroup.h | 1 +
kernel/cgroup.c | 2 ++
2 files changed, 3 insertions(+)
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -612,6 +612,7 @@ struct cgroup_subsys {
struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css);
int (*css_online)(struct cgroup_subsys_state *css);
void (*css_offline)(struct cgroup_subsys_state *css);
+ void (*css_released)(struct cgroup_subsys_state *css);
void (*css_free)(struct cgroup_subsys_state *css);
void (*css_reset)(struct cgroup_subsys_state *css);
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4380,6 +4380,8 @@ static void css_release_work_fn(struct w
if (ss) {
/* css release path */
cgroup_idr_remove(&ss->css_idr, css->id);
+ if (ss->css_released)
+ ss->css_released(css);
} else {
/* cgroup release path */
cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
--
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