diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index e267e62827bbc4e564c930576fcee8b70a8c4a79..e4e8e117d27d9171f23cdc54b69011758243c3da 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 0066092de19a7f0522810f11194a80d4a31409df..492215d67fa5c3f153f6b1de42416ec4a1653298 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) {