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authorTejun Heo <tj@kernel.org>2013-06-12 20:43:06 -0700
committerTejun Heo <tj@kernel.org>2013-06-12 20:43:06 -0700
commit6a24474da83ea7c8b7d32f05f858b1259994067a (patch)
tree88633b53318c1adb8f648eaf5edcabac8f81b01b /include/linux/percpu-refcount.h
parentc1ae6e9b4db00023b9caed72af49a93abad46452 (diff)
downloadop-kernel-dev-6a24474da83ea7c8b7d32f05f858b1259994067a.zip
op-kernel-dev-6a24474da83ea7c8b7d32f05f858b1259994067a.tar.gz
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 <tj@kernel.org> Reported-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: Kent Overstreet <koverstreet@google.com>
Diffstat (limited to 'include/linux/percpu-refcount.h')
-rw-r--r--include/linux/percpu-refcount.h8
1 files changed, 4 insertions, 4 deletions
diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h
index 24b31ef..abe1411 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
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