diff options
| author | Michel Lespinasse <walken@google.com> | 2013-05-07 15:45:56 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-05-07 16:20:16 +0200 |
| commit | a7d2c573ae7fad1b2c877d1a1342fa5bb0d6478c (patch) | |
| tree | 1494f94f71a299d32a3584565a538e5ffdef1163 /lib/rwsem.c | |
| parent | rwsem: use cmpxchg for trying to steal write lock (diff) | |
| download | linux-a7d2c573ae7fad1b2c877d1a1342fa5bb0d6478c.tar.xz linux-a7d2c573ae7fad1b2c877d1a1342fa5bb0d6478c.zip | |
rwsem: avoid taking wait_lock in rwsem_down_write_failed
In rwsem_down_write_failed(), if there are active locks after we wake up
(i.e. the lock got stolen from us), skip taking the wait_lock and go
back to sleep immediately.
Signed-off-by: Michel Lespinasse <walken@google.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Acked-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to '')
| -rw-r--r-- | lib/rwsem.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/lib/rwsem.c b/lib/rwsem.c index 64c2dc007be2..edf3d9ca670e 100644 --- a/lib/rwsem.c +++ b/lib/rwsem.c @@ -214,8 +214,8 @@ struct rw_semaphore __sched *rwsem_down_write_failed(struct rw_semaphore *sem) sem = __rwsem_do_wake(sem, RWSEM_WAKE_READ_OWNED); /* wait until we successfully acquire the lock */ + set_task_state(tsk, TASK_UNINTERRUPTIBLE); while (true) { - set_task_state(tsk, TASK_UNINTERRUPTIBLE); /* Try acquiring the write lock. */ count = RWSEM_ACTIVE_WRITE_BIAS; @@ -226,7 +226,13 @@ struct rw_semaphore __sched *rwsem_down_write_failed(struct rw_semaphore *sem) break; raw_spin_unlock_irq(&sem->wait_lock); - schedule(); + + /* Block until there are no active lockers. */ + do { + schedule(); + set_task_state(tsk, TASK_UNINTERRUPTIBLE); + } while (sem->count & RWSEM_ACTIVE_MASK); + raw_spin_lock_irq(&sem->wait_lock); } |