locking/rwsem: Introduce rwsem_write_trylock()

One copy of this logic is better than three.

Peter Zijlstra committed 5 years ago

Commit 285c61a1 parent 33791161 file · +16 −22Browse files

Showing the changes to kernel/locking (1 of 1 file). Show all

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@@ -285,6 +285,18 @@ static inline bool rwsem_read_trylock(struct rw_semaphore *sem) · 284 unmodified lines
285	return false;	285	return false;
286	}	286	}
287		287
		288	static inline bool rwsem_write_trylock(struct rw_semaphore *sem)
		289	{
		290	long tmp = RWSEM_UNLOCKED_VALUE;
		291
		292	if (atomic_long_try_cmpxchg_acquire(&sem->count, &tmp, RWSEM_WRITER_LOCKED)) {
		293	rwsem_set_owner(sem);
		294	return true;
		295	}
		296
		297	return false;
		298	}
		299
288	/*	300	/*
289	* Return just the real task structure pointer of the owner	301	* Return just the real task structure pointer of the owner
290	*/	302	*/
@@ -1395,42 +1407,24 @@ static inline int __down_read_trylock(struct rw_semaphore *sem) · 1104 unmodified lines
1395	*/	1407	*/
1396	static inline void __down_write(struct rw_semaphore *sem)	1408	static inline void __down_write(struct rw_semaphore *sem)
1397	{	1409	{
1398	long tmp = RWSEM_UNLOCKED_VALUE;	1410	if (unlikely(!rwsem_write_trylock(sem)))
1399
1400	if (unlikely(!atomic_long_try_cmpxchg_acquire(&sem->count, &tmp,
1401	RWSEM_WRITER_LOCKED)))
1402	rwsem_down_write_slowpath(sem, TASK_UNINTERRUPTIBLE);	1411	rwsem_down_write_slowpath(sem, TASK_UNINTERRUPTIBLE);
1403	else
1404	rwsem_set_owner(sem);
1405	}	1412	}
1406		1413
1407	static inline int __down_write_killable(struct rw_semaphore *sem)	1414	static inline int __down_write_killable(struct rw_semaphore *sem)
1408	{	1415	{
1409	long tmp = RWSEM_UNLOCKED_VALUE;	1416	if (unlikely(!rwsem_write_trylock(sem))) {
1410
1411	if (unlikely(!atomic_long_try_cmpxchg_acquire(&sem->count, &tmp,
1412	RWSEM_WRITER_LOCKED))) {
1413	if (IS_ERR(rwsem_down_write_slowpath(sem, TASK_KILLABLE)))	1417	if (IS_ERR(rwsem_down_write_slowpath(sem, TASK_KILLABLE)))
1414	return -EINTR;	1418	return -EINTR;
1415	} else {
1416	rwsem_set_owner(sem);
1417	}	1419	}
		1420
1418	return 0;	1421	return 0;
1419	}	1422	}
1420		1423
1421	static inline int __down_write_trylock(struct rw_semaphore *sem)	1424	static inline int __down_write_trylock(struct rw_semaphore *sem)
1422	{	1425	{
1423	long tmp;
1424
1425	DEBUG_RWSEMS_WARN_ON(sem->magic != sem, sem);	1426	DEBUG_RWSEMS_WARN_ON(sem->magic != sem, sem);
1426		1427	return rwsem_write_trylock(sem);
1427	tmp = RWSEM_UNLOCKED_VALUE;
1428	if (atomic_long_try_cmpxchg_acquire(&sem->count, &tmp,
1429	RWSEM_WRITER_LOCKED)) {
1430	rwsem_set_owner(sem);
1431	return true;
1432	}
1433	return false;
1434	}	1428	}
1435		1429
1436	/*	1430	/*