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Subject[PATCH V8 5/8] percpu-refcount: introduce __percpu_ref_tryget_live
Date
Block layer need to call this function after holding
rcu lock in a real hot path, so introduce this helper.

Cc: Bart Van Assche <Bart.VanAssche@wdc.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
include/linux/percpu-refcount.h | 27 +++++++++++++++++----------
1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h
index c13dceb87b60..a0f22586a28d 100644
--- a/include/linux/percpu-refcount.h
+++ b/include/linux/percpu-refcount.h
@@ -221,6 +221,21 @@ static inline bool percpu_ref_tryget(struct percpu_ref *ref)
return ret;
}

+static inline bool __percpu_ref_tryget_live(struct percpu_ref *ref)
+{
+ unsigned long __percpu *percpu_count;
+ bool ret = false;
+
+ if (__ref_is_percpu(ref, &percpu_count)) {
+ this_cpu_inc(*percpu_count);
+ ret = true;
+ } else if (!(ref->percpu_count_ptr & __PERCPU_REF_DEAD)) {
+ ret = atomic_long_inc_not_zero(&ref->count);
+ }
+
+ return ret;
+}
+
/**
* percpu_ref_tryget_live - try to increment a live percpu refcount
* @ref: percpu_ref to try-get
@@ -238,18 +253,10 @@ static inline bool percpu_ref_tryget(struct percpu_ref *ref)
*/
static inline bool percpu_ref_tryget_live(struct percpu_ref *ref)
{
- unsigned long __percpu *percpu_count;
- bool ret = false;
+ bool ret;

rcu_read_lock_sched();
-
- if (__ref_is_percpu(ref, &percpu_count)) {
- this_cpu_inc(*percpu_count);
- ret = true;
- } else if (!(ref->percpu_count_ptr & __PERCPU_REF_DEAD)) {
- ret = atomic_long_inc_not_zero(&ref->count);
- }
-
+ ret = __percpu_ref_tryget_live(ref);
rcu_read_unlock_sched();

return ret;
--
2.9.5
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