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author | Michel Lespinasse <walken@google.com> | 2013-05-07 06:45:50 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-05-07 07:20:16 -0700 |
commit | f7dd1cee9a4e2b1450e4a3732636dfbf28562ee4 (patch) | |
tree | 4dc69d1b121d07d25d6dac56fd33eaffd6dac91f /lib | |
parent | e2d57f782c8a906f80d5b5f54da803c1638929d7 (diff) | |
download | linux-stable-f7dd1cee9a4e2b1450e4a3732636dfbf28562ee4.tar.gz linux-stable-f7dd1cee9a4e2b1450e4a3732636dfbf28562ee4.tar.bz2 linux-stable-f7dd1cee9a4e2b1450e4a3732636dfbf28562ee4.zip |
rwsem: shorter spinlocked section in rwsem_down_failed_common()
This change reduces the size of the spinlocked and TASK_UNINTERRUPTIBLE
sections in rwsem_down_failed_common():
- We only need the sem->wait_lock to insert ourselves on the wait_list;
the waiter node can be prepared outside of the wait_lock.
- The task state only needs to be set to TASK_UNINTERRUPTIBLE immediately
before checking if we actually need to sleep; it doesn't need to protect
the entire function.
Signed-off-by: Michel Lespinasse <walken@google.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Acked-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r-- | lib/rwsem.c | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/lib/rwsem.c b/lib/rwsem.c index 672eb33218ac..40636454cf3c 100644 --- a/lib/rwsem.c +++ b/lib/rwsem.c @@ -188,14 +188,12 @@ rwsem_down_failed_common(struct rw_semaphore *sem, struct task_struct *tsk = current; signed long count; - set_task_state(tsk, TASK_UNINTERRUPTIBLE); - /* set up my own style of waitqueue */ - raw_spin_lock_irq(&sem->wait_lock); waiter.task = tsk; waiter.type = type; get_task_struct(tsk); + raw_spin_lock_irq(&sem->wait_lock); if (list_empty(&sem->wait_list)) adjustment += RWSEM_WAITING_BIAS; list_add_tail(&waiter.list, &sem->wait_list); @@ -218,7 +216,8 @@ rwsem_down_failed_common(struct rw_semaphore *sem, raw_spin_unlock_irq(&sem->wait_lock); /* wait to be given the lock */ - for (;;) { + while (true) { + set_task_state(tsk, TASK_UNINTERRUPTIBLE); if (!waiter.task) break; @@ -231,7 +230,6 @@ rwsem_down_failed_common(struct rw_semaphore *sem, } raw_spin_unlock_irq(&sem->wait_lock); schedule(); - set_task_state(tsk, TASK_UNINTERRUPTIBLE); } tsk->state = TASK_RUNNING; |