locking/percpu-rwsem: Fold __percpu_up_read() (ac8dec42) · Commits · 戴 / test

include/linux/percpu-rwsem.h

+15 −4

Original line number	Diff line number	Diff line
		@@ -43,7 +43,6 @@ is_static struct percpu_rw_semaphore name = { \
		__DEFINE_PERCPU_RWSEM(name, static)

		extern bool __percpu_down_read(struct percpu_rw_semaphore *, bool);
		extern void __percpu_up_read(struct percpu_rw_semaphore *);

		static inline void percpu_down_read(struct percpu_rw_semaphore *sem)
		{
		@@ -103,10 +102,22 @@ static inline void percpu_up_read(struct percpu_rw_semaphore *sem)
		/*
		* Same as in percpu_down_read().
		*/
		if (likely(rcu_sync_is_idle(&sem->rss)))
		if (likely(rcu_sync_is_idle(&sem->rss))) {
		__this_cpu_dec(*sem->read_count);
		else
		__percpu_up_read(sem); /* Unconditional memory barrier */
		} else {
		/*
		* slowpath; reader will only ever wake a single blocked
		* writer.
		*/
		smp_mb(); /* B matches C */
		/*
		* In other words, if they see our decrement (presumably to
		* aggregate zero, as that is the only time it matters) they
		* will also see our critical section.
		*/
		__this_cpu_dec(*sem->read_count);
		rcuwait_wake_up(&sem->writer);
		}
		preempt_enable();
		}

+1 −0

Original line number	Diff line number	Diff line
		@@ -258,6 +258,7 @@ void rcuwait_wake_up(struct rcuwait *w)
		wake_up_process(task);
		rcu_read_unlock();
		}
		EXPORT_SYMBOL_GPL(rcuwait_wake_up);

		/*
		* Determine if a process group is "orphaned", according to the POSIX

+0 −15

Original line number	Diff line number	Diff line
		@@ -177,21 +177,6 @@ bool __percpu_down_read(struct percpu_rw_semaphore *sem, bool try)
		}
		EXPORT_SYMBOL_GPL(__percpu_down_read);

		void __percpu_up_read(struct percpu_rw_semaphore *sem)
		{
		smp_mb(); /* B matches C */
		/*
		* In other words, if they see our decrement (presumably to aggregate
		* zero, as that is the only time it matters) they will also see our
		* critical section.
		*/
		__this_cpu_dec(*sem->read_count);

		/* Prod writer to re-evaluate readers_active_check() */
		rcuwait_wake_up(&sem->writer);
		}
		EXPORT_SYMBOL_GPL(__percpu_up_read);

		#define per_cpu_sum(var) \
		({ \
		typeof(var) __sum = 0; \