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 <vdavydov@xxxxxxxxxxxxx>
---
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
--
1.7.10.4
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