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-rw-r--r--include/linux/cgroup.h1
-rw-r--r--kernel/cgroup.c7
2 files changed, 6 insertions, 2 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index e267e62827bb..e4e8e117d27d 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -99,6 +99,7 @@ static inline bool css_tryget(struct cgroup_subsys_state *css)
while (!atomic_inc_not_zero(&css->refcnt)) {
if (test_bit(CSS_REMOVED, &css->flags))
return false;
+ cpu_relax();
}
return true;
}
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 0066092de19a..492215d67fa5 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2509,7 +2509,7 @@ static int cgroup_clear_css_refs(struct cgroup *cgrp)
for_each_subsys(cgrp->root, ss) {
struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
int refcnt;
- do {
+ while (1) {
/* We can only remove a CSS with a refcnt==1 */
refcnt = atomic_read(&css->refcnt);
if (refcnt > 1) {
@@ -2523,7 +2523,10 @@ static int cgroup_clear_css_refs(struct cgroup *cgrp)
* css_tryget() to spin until we set the
* CSS_REMOVED bits or abort
*/
- } while (atomic_cmpxchg(&css->refcnt, refcnt, 0) != refcnt);
+ if (atomic_cmpxchg(&css->refcnt, refcnt, 0) == refcnt)
+ break;
+ cpu_relax();
+ }
}
done:
for_each_subsys(cgrp->root, ss) {