For now bindable subsystems should not use css_get/put(), so warn
on this misuse.
Signed-off-by: Li Zefan <l...@cn.fujitsu.com>
---
include/linux/cgroup.h | 7 +++++--
kernel/cgroup.c | 3 +++
2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 1e4e1df..10e4e02 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);
}
@@ -119,6 +121,7 @@ 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 12c1f7c..88e265d 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -936,6 +936,9 @@ static void init_cgroup_css(struct cgroup_subsys_state *css,
css->cgroup = cgrp;
atomic_set(&css->refcnt, 1);
css->flags = 0;
+ /* For now, a bindable subsystem should not call css_get/put(). */
+ if (ss->can_bind)
+ set_bit(CSS_NO_GET, &css->flags);
css->id = NULL;
if (cgrp == dummytop)
set_bit(CSS_ROOT, &css->flags);
--
1.7.0.1
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