[PATCH RFC 2/3] percpu-refcount: allow to get dead reference
From: Vladimir Davydov <hidden>
Date: 2014-05-13 13:48:57
Also in:
lkml
Subsystem:
per-cpu memory allocator, the rest · Maintainers:
Dennis Zhou, Tejun Heo, Christoph Lameter, Linus Torvalds
Currently percpu_ref_tryget fails after percpu_ref_kill is called, even if refcnt != 0. In the next patch I need a method to get a ref that will only fail if refcnt == 0, so let's extend the interface to percpu ref a bit to allow that. Signed-off-by: Vladimir Davydov <redacted> --- include/linux/percpu-refcount.h | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h
index 95961f0bf62d..7729e59b9cb7 100644
--- a/include/linux/percpu-refcount.h
+++ b/include/linux/percpu-refcount.h@@ -129,7 +129,8 @@ static inline void percpu_ref_get(struct percpu_ref *ref) * used. After the confirm_kill callback is invoked, it's guaranteed that * no new reference will be given out by percpu_ref_tryget(). */ -static inline bool percpu_ref_tryget(struct percpu_ref *ref) +static inline bool __percpu_ref_tryget(struct percpu_ref *ref, + bool maybe_dead) { unsigned __percpu *pcpu_count; int ret = false;
@@ -141,13 +142,19 @@ static inline bool percpu_ref_tryget(struct percpu_ref *ref) if (likely(REF_STATUS(pcpu_count) == PCPU_REF_PTR)) { __this_cpu_inc(*pcpu_count); ret = true; - } + } else if (maybe_dead && unlikely(atomic_read(&ref->count))) + ret = atomic_inc_not_zero(&ref->count); rcu_read_unlock_sched(); return ret; } +static inline bool percpu_ref_tryget(struct percpu_ref *ref) +{ + return __percpu_ref_tryget(ref, false); +} + /** * percpu_ref_put - decrement a percpu refcount * @ref: percpu_ref to put
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1.7.10.4
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