locking/percpu-rwsem: Extract __percpu_down_read_trylock() (75ff6457) · Commits · 戴 / test

In preparation for removing the embedded rwsem and building a custom lock, extract the read-trylock primitive. Signed-off-by:

kernel/locking/percpu-rwsem.c

+13 −6

Original line number	Diff line number	Diff line
		@@ -45,7 +45,7 @@ void percpu_free_rwsem(struct percpu_rw_semaphore *sem)
		}
		EXPORT_SYMBOL_GPL(percpu_free_rwsem);

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

		@@ -73,11 +73,18 @@ bool __percpu_down_read(struct percpu_rw_semaphore *sem, bool try)
		if (likely(!smp_load_acquire(&sem->readers_block)))
		return true;

		/*
		* Per the above comment; we still have preemption disabled and
		* will thus decrement on the same CPU as we incremented.
		*/
		__percpu_up_read(sem);
		__this_cpu_dec(*sem->read_count);

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

		return false;
		}

		bool __percpu_down_read(struct percpu_rw_semaphore *sem, bool try)
		{
		if (__percpu_down_read_trylock(sem))
		return true;

		if (try)
		return false;