For now unbindable subsystems should not use css_get/put(), so check
this misuse.
Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
---
include/linux/cgroup.h | 7 +++++--
kernel/cgroup.c | 5 +++++
2 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 17579b2..e8ad9f1 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -80,13 +80,15 @@ struct cgroup_subsys_state {
/* bits in struct cgroup_subsys_state flags field */
enum {
- CSS_ROOT, /* This CSS is the root of the subsystem */
- CSS_REMOVED, /* This CSS is dead */
+ CSS_ROOT, /* This CSS is the root of the subsystem */
+ CSS_REMOVED, /* This CSS is dead */
+ CSS_NO_GET, /* Forbid calling css_get/put() */
};
/* Caller must verify that the css is not for root cgroup */
static inline void __css_get(struct cgroup_subsys_state *css, int count)
{
+ BUG_ON(test_bit(CSS_NO_GET, &css->flags));
atomic_add(count, &css->refcnt);
}
@@ -131,6 +133,7 @@ static inline bool css_tryget(struct cgroup_subsys_state *css)
{
if (test_bit(CSS_ROOT, &css->flags))
return true;
+ BUG_ON(test_bit(CSS_NO_GET, &css->flags));
while (!atomic_inc_not_zero(&css->refcnt)) {
if (test_bit(CSS_REMOVED, &css->flags))
return false;
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index fa2c5de..d49a459 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -938,6 +938,11 @@ static void init_cgroup_css(struct cgroup_subsys_state *css,
atomic_set(&css->refcnt, 1);
css->flags = 0;
css->id = NULL;
+
+ /* For now, unbindable subsystems should not call css_get/put(). */
+ if (ss->unbindable)
+ set_bit(CSS_NO_GET, &css->flags);
+
if (cgrp == dummytop)
set_bit(CSS_ROOT, &css->flags);
BUG_ON(cgrp->subsys[ss->subsys_id]);
--
1.6.3
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