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

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Message-ID: <1317024050.9084.62.camel@twins>
Date:	Mon, 26 Sep 2011 10:00:49 +0200
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Manfred Spraul <manfred@...orfullife.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Mike Galbraith <efault@....de>
Subject: Re: [PATCH 3/3] [RFC] ipc/sem.c: replace busy loop with completion

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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