locking/percpu-rwsem: Move __this_cpu_inc() into the slowpath (71365d40) · Commits · 戴 / test

include/linux/percpu-rwsem.h

+6 −4

Original line number	Diff line number	Diff line
		@@ -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.
		*/
		if (likely(rcu_sync_is_idle(&sem->rss)))
		__this_cpu_inc(*sem->read_count);
		if (unlikely(!rcu_sync_is_idle(&sem->rss)))
		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().
		*/
		if (likely(rcu_sync_is_idle(&sem->rss)))
		__this_cpu_inc(*sem->read_count);
		if (unlikely(!rcu_sync_is_idle(&sem->rss)))
		else
		ret = __percpu_down_read(sem, true); /* Unconditional memory barrier */
		preempt_enable();
		/*

+2 −0

Original line number	Diff line number	Diff line
		@@ -47,6 +47,8 @@ EXPORT_SYMBOL_GPL(percpu_free_rwsem);

		bool __percpu_down_read(struct percpu_rw_semaphore *sem, bool try)
		{
		__this_cpu_inc(*sem->read_count);

		/*
		* Due to having preemption disabled the decrement happens on
		* the same CPU as the increment, avoiding the