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authorPeter Zijlstra <peterz@infradead.org>2020-12-08 10:22:16 +0100
committerPeter Zijlstra <peterz@infradead.org>2020-12-09 17:08:47 +0100
commit3379116a0ca965b00e6522c7ea3f16c9dbd8f9f9 (patch)
tree9a369976c1259daaa296ad07e01fe8148d2df236 /kernel/locking
parent2b3c99ee6389d33aff91d9e7a55465d7d1332bbd (diff)
locking/rwsem: Better collate rwsem_read_trylock()
All users of rwsem_read_trylock() do rwsem_set_reader_owned(sem) on success, move it into rwsem_read_trylock() proper. 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.c15
1 files changed, 8 insertions, 7 deletions
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index a163542d178e..5c0dc7ebace9 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -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;
}