Commit aa6c618f authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Yang Yingliang
Browse files

locking/rwsem: Better collate rwsem_read_trylock() 

mainline inclusion
from mainline-v5.11-rc1
commit 3379116a
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7A0N9
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3379116a0ca965b00e6522c7ea3f16c9dbd8f9f9



--------------------------------

All users of rwsem_read_trylock() do rwsem_set_reader_owned(sem) on
success, move it into rwsem_read_trylock() proper.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201207090243.GE3040@hirez.programming.kicks-ass.net


Signed-off-by: default avatarYang Yingliang <yangyingliang@huawei.com>
parent d8fcd2f3

kernel/locking/rwsem.c

+8 −7
Original line number Diff line number Diff line
@@ -273,9 +273,16 @@ static inline void rwsem_set_nonspinnable(struct rw_semaphore *sem) 
static inline bool rwsem_read_trylock(struct rw_semaphore *sem)

{

	long cnt = atomic_long_add_return_acquire(RWSEM_READER_BIAS, &sem->count);



	if (WARN_ON_ONCE(cnt < 0))

		rwsem_set_nonspinnable(sem);

	return !(cnt & RWSEM_READ_FAILED_MASK);



	if (!(cnt & RWSEM_READ_FAILED_MASK)) {

		rwsem_set_reader_owned(sem);

		return true;

	}



	return false;

}



/*
@@ -1340,8 +1347,6 @@ static inline void __down_read(struct rw_semaphore *sem) 
	if (!rwsem_read_trylock(sem)) {

		rwsem_down_read_slowpath(sem, TASK_UNINTERRUPTIBLE);

		DEBUG_RWSEMS_WARN_ON(!is_rwsem_reader_owned(sem), sem);

	} else {

		rwsem_set_reader_owned(sem);

	}

}
@@ -1351,8 +1356,6 @@ static inline int __down_read_interruptible(struct rw_semaphore *sem) 
		if (IS_ERR(rwsem_down_read_slowpath(sem, TASK_INTERRUPTIBLE)))

			return -EINTR;

		DEBUG_RWSEMS_WARN_ON(!is_rwsem_reader_owned(sem), sem);

	} else {

		rwsem_set_reader_owned(sem);

	}

	return 0;

}
@@ -1363,8 +1366,6 @@ static inline int __down_read_killable(struct rw_semaphore *sem) 
		if (IS_ERR(rwsem_down_read_slowpath(sem, TASK_KILLABLE)))

			return -EINTR;

		DEBUG_RWSEMS_WARN_ON(!is_rwsem_reader_owned(sem), sem);

	} else {

		rwsem_set_reader_owned(sem);

	}

	return 0;

}