locking/rwsem: Pass the current atomic count to rwsem_down_read_slowpath() (c8fe8b05) · Commits · 戴 / test

kernel/locking/rwsem.c

+10 −8

Original line number	Diff line number	Diff line
		@@ -270,14 +270,14 @@ static inline void rwsem_set_nonspinnable(struct rw_semaphore *sem)
		owner \| RWSEM_NONSPINNABLE));
		}

		static inline bool rwsem_read_trylock(struct rw_semaphore *sem)
		static inline bool rwsem_read_trylock(struct rw_semaphore sem, long cntp)
		{
		long cnt = atomic_long_add_return_acquire(RWSEM_READER_BIAS, &sem->count);
		*cntp = atomic_long_add_return_acquire(RWSEM_READER_BIAS, &sem->count);

		if (WARN_ON_ONCE(cnt < 0))
		if (WARN_ON_ONCE(*cntp < 0))
		rwsem_set_nonspinnable(sem);

		if (!(cnt & RWSEM_READ_FAILED_MASK)) {
		if (!(*cntp & RWSEM_READ_FAILED_MASK)) {
		rwsem_set_reader_owned(sem);
		return true;
		}
		@@ -1008,9 +1008,9 @@ rwsem_spin_on_owner(struct rw_semaphore *sem, unsigned long nonspinnable)
		* Wait for the read lock to be granted
		*/
		static struct rw_semaphore __sched *
		rwsem_down_read_slowpath(struct rw_semaphore *sem, int state)
		rwsem_down_read_slowpath(struct rw_semaphore *sem, long count, int state)
		{
		long count, adjustment = -RWSEM_READER_BIAS;
		long adjustment = -RWSEM_READER_BIAS;
		struct rwsem_waiter waiter;
		DEFINE_WAKE_Q(wake_q);
		bool wake = false;
		@@ -1356,8 +1356,10 @@ static struct rw_semaphore rwsem_downgrade_wake(struct rw_semaphore sem)
		*/
		static inline int __down_read_common(struct rw_semaphore *sem, int state)
		{
		if (!rwsem_read_trylock(sem)) {
		if (IS_ERR(rwsem_down_read_slowpath(sem, state)))
		long count;

		if (!rwsem_read_trylock(sem, &count)) {
		if (IS_ERR(rwsem_down_read_slowpath(sem, count, state)))
		return -EINTR;
		DEBUG_RWSEMS_WARN_ON(!is_rwsem_reader_owned(sem), sem);
		}

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