Re: [PATCH 3/3] [RFC] ipc/sem.c: replace busy loop with completion

From: Peter Zijlstra
Date: Mon Sep 26 2011 - 04:01:23 EST


On Sat, 2011-09-24 at 19:37 +0200, Manfred Spraul wrote:

sma = sem_lock(ns, semid);

> @@ -1456,8 +1414,17 @@ sleep_again:
> /*
> * Wait until it's guaranteed that no wakeup_sem_queue_do() is ongoing.
> */
> - error = get_queue_result(&queue);
> -
> + error = queue.status;
> + if (error != -EINTR) {
> + /* If there is a return code, then we can leave immediately. */
> + if (!IS_ERR(sma)) {
> + sem_unlock(sma);
> + }
> + /* Except that we must wait for the hands-off */
> + wait_for_completion(&queue.done);
> + goto out_free;

you just lost a sem_unlock() in the IS_ERR() case.

> + }
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