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

diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index a163542d178ee11198080f6cad124c9e2c25d115..5c0dc7ebace9fd08539584c5304a8815eccf3da9 100644 (file)
--- 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;
 }