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authorPeter Zijlstra <peterz@infradead.org>2019-10-30 22:17:51 +0300
committerIngo Molnar <mingo@kernel.org>2020-02-11 15:10:54 +0300
commit71365d40232110f7b029befc9033ea311d680611 (patch)
treeda9cf44abea7c38e244c2b2dd7e6ef587c4146dc /include/linux/percpu-rwsem.h
parent206c98ffbeda588dbbd9d272505c42acbc364a30 (diff)
downloadlinux-71365d40232110f7b029befc9033ea311d680611.tar.xz
locking/percpu-rwsem: Move __this_cpu_inc() into the slowpath
As preparation to rework __percpu_down_read() move the __this_cpu_inc() into it. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Will Deacon <will@kernel.org> Acked-by: Waiman Long <longman@redhat.com> Tested-by: Juri Lelli <juri.lelli@redhat.com> Link: https://lkml.kernel.org/r/20200131151540.041600199@infradead.org
Diffstat (limited to 'include/linux/percpu-rwsem.h')
-rw-r--r--include/linux/percpu-rwsem.h10
1 files changed, 6 insertions, 4 deletions
diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h
index 4ceaa1921951..bb5b71c1e446 100644
--- a/include/linux/percpu-rwsem.h
+++ b/include/linux/percpu-rwsem.h
@@ -59,8 +59,9 @@ static inline void percpu_down_read(struct percpu_rw_semaphore *sem)
* and that once the synchronize_rcu() is done, the writer will see
* anything we did within this RCU-sched read-size critical section.
*/
- __this_cpu_inc(*sem->read_count);
- if (unlikely(!rcu_sync_is_idle(&sem->rss)))
+ if (likely(rcu_sync_is_idle(&sem->rss)))
+ __this_cpu_inc(*sem->read_count);
+ else
__percpu_down_read(sem, false); /* Unconditional memory barrier */
/*
* The preempt_enable() prevents the compiler from
@@ -77,8 +78,9 @@ static inline bool percpu_down_read_trylock(struct percpu_rw_semaphore *sem)
/*
* Same as in percpu_down_read().
*/
- __this_cpu_inc(*sem->read_count);
- if (unlikely(!rcu_sync_is_idle(&sem->rss)))
+ if (likely(rcu_sync_is_idle(&sem->rss)))
+ __this_cpu_inc(*sem->read_count);
+ else
ret = __percpu_down_read(sem, true); /* Unconditional memory barrier */
preempt_enable();
/*