From 6a24474da83ea7c8b7d32f05f858b1259994067a Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 12 Jun 2013 20:43:06 -0700 Subject: [PATCH] percpu-refcount: consistently use plain (non-sched) RCU percpu_ref_get/put() are using preempt_disable/enable() while percpu_ref_kill() is using plain call_rcu() instead of call_rcu_sched(). This is buggy as grace periods of the two may not match. Fix it by using plain RCU in percpu_ref_get/put(). (I suggested using sched RCU in the first place but there's no actual benefit in doing so unless we're gonna introduce different variants of get/put to be called while preemption is alredy disabled, which we definitely shouldn't.) Signed-off-by: Tejun Heo Reported-by: Rusty Russell Acked-by: Kent Overstreet --- include/linux/percpu-refcount.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h index 24b31ef15932..abe141172d96 100644 --- a/include/linux/percpu-refcount.h +++ b/include/linux/percpu-refcount.h @@ -85,7 +85,7 @@ static inline void percpu_ref_get(struct percpu_ref *ref) { unsigned __percpu *pcpu_count; - preempt_disable(); + rcu_read_lock(); pcpu_count = ACCESS_ONCE(ref->pcpu_count); @@ -94,7 +94,7 @@ static inline void percpu_ref_get(struct percpu_ref *ref) else atomic_inc(&ref->count); - preempt_enable(); + rcu_read_unlock(); } /** @@ -107,7 +107,7 @@ static inline void percpu_ref_put(struct percpu_ref *ref) { unsigned __percpu *pcpu_count; - preempt_disable(); + rcu_read_lock(); pcpu_count = ACCESS_ONCE(ref->pcpu_count); @@ -116,7 +116,7 @@ static inline void percpu_ref_put(struct percpu_ref *ref) else if (unlikely(atomic_dec_and_test(&ref->count))) ref->release(ref); - preempt_enable(); + rcu_read_unlock(); } #endif -- 2.34.1