epoll: optimize setting task running after blocking

After waking up a task waiting for an event, we explicitly mark it as
TASK_RUNNING (which is necessary as we do the checks for wakeups as
TASK_INTERRUPTIBLE).  Once running and dealing with actually delivering
the events, we're obviously not planning on calling schedule, thus we can
relax the implied barrier and simply update the state with
__set_current_state().

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index d77f944..1e009ca 100644 (file)
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1639,9 +1639,9 @@ fetch_events:
 
                        spin_lock_irqsave(&ep->lock, flags);
                }
-               __remove_wait_queue(&ep->wq, &wait);
 
-               set_current_state(TASK_RUNNING);
+               __remove_wait_queue(&ep->wq, &wait);
+               __set_current_state(TASK_RUNNING);
        }
 check_events:
        /* Is it worth to try to dig for events ? */