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| author | Peter Zijlstra <peterz@infradead.org> | 2020-12-08 10:25:06 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2020-12-09 17:08:47 +0100 |
| commit | 285c61aedf6bc5d81b37e4dc48c19012e8ff9836 (patch) | |
| tree | 1ad5d619fbcc91f2281a9fb85d42af0a468fda30 /kernel/locking | |
| parent | locking/rwsem: Better collate rwsem_read_trylock() (diff) | |
| download | linux-285c61aedf6bc5d81b37e4dc48c19012e8ff9836.tar.xz linux-285c61aedf6bc5d81b37e4dc48c19012e8ff9836.zip | |
locking/rwsem: Introduce rwsem_write_trylock()
One copy of this logic is better than three.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201207090243.GE3040@hirez.programming.kicks-ass.net
Diffstat (limited to 'kernel/locking')
| -rw-r--r-- | kernel/locking/rwsem.c | 38 |
1 files changed, 16 insertions, 22 deletions
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c index 5c0dc7ebace9..7915456b9dfa 100644 --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -285,6 +285,18 @@ static inline bool rwsem_read_trylock(struct rw_semaphore *sem) return false; } +static inline bool rwsem_write_trylock(struct rw_semaphore *sem) +{ + long tmp = RWSEM_UNLOCKED_VALUE; + + if (atomic_long_try_cmpxchg_acquire(&sem->count, &tmp, RWSEM_WRITER_LOCKED)) { + rwsem_set_owner(sem); + return true; + } + + return false; +} + /* * Return just the real task structure pointer of the owner */ @@ -1395,42 +1407,24 @@ static inline int __down_read_trylock(struct rw_semaphore *sem) */ static inline void __down_write(struct rw_semaphore *sem) { - long tmp = RWSEM_UNLOCKED_VALUE; - - if (unlikely(!atomic_long_try_cmpxchg_acquire(&sem->count, &tmp, - RWSEM_WRITER_LOCKED))) + if (unlikely(!rwsem_write_trylock(sem))) rwsem_down_write_slowpath(sem, TASK_UNINTERRUPTIBLE); - else - rwsem_set_owner(sem); } static inline int __down_write_killable(struct rw_semaphore *sem) { - long tmp = RWSEM_UNLOCKED_VALUE; - - if (unlikely(!atomic_long_try_cmpxchg_acquire(&sem->count, &tmp, - RWSEM_WRITER_LOCKED))) { + if (unlikely(!rwsem_write_trylock(sem))) { if (IS_ERR(rwsem_down_write_slowpath(sem, TASK_KILLABLE))) return -EINTR; - } else { - rwsem_set_owner(sem); } + return 0; } static inline int __down_write_trylock(struct rw_semaphore *sem) { - long tmp; - DEBUG_RWSEMS_WARN_ON(sem->magic != sem, sem); - - tmp = RWSEM_UNLOCKED_VALUE; - if (atomic_long_try_cmpxchg_acquire(&sem->count, &tmp, - RWSEM_WRITER_LOCKED)) { - rwsem_set_owner(sem); - return true; - } - return false; + return rwsem_write_trylock(sem); } /* |