sched: refactor wait_for_completion_timeout()

Simplify the code and fix the boundary condition of
wait_for_completion_timeout(,0).

We can kill the first __remove_wait_queue() as well.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

1 files changed, 6 insertions, 18 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 577f160131bd..bebf9788f45e 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4398,32 +4398,20 @@ do_wait_for_common(struct completion *x, long timeout, int state)
                              signal_pending(current)) ||
                             (state == TASK_KILLABLE &&
                              fatal_signal_pending(current))) {
-                                __remove_wait_queue(&x->wait, &wait);
-                                return -ERESTARTSYS;
+                                timeout = -ERESTARTSYS;
+                                break;
                         }
                         __set_current_state(state);
                         spin_unlock_irq(&x->wait.lock);
                         timeout = schedule_timeout(timeout);
                         spin_lock_irq(&x->wait.lock);
-
-                        /*
-                         * If the completion has arrived meanwhile
-                         * then return 1 jiffy time left:
-                         */
-                        if (x->done && !timeout) {
-                                timeout = 1;
-                                break;
-                        }
-
-                        if (!timeout) {
-                                __remove_wait_queue(&x->wait, &wait);
-                                return timeout;
-                        }
-                } while (!x->done);
+                } while (!x->done && timeout);
                 __remove_wait_queue(&x->wait, &wait);
+                if (!x->done)
+                        return timeout;
         }
         x->done--;
-        return timeout;
+        return timeout ?: 1;
 }
 
 static long __sched