linux-kernel - Re: [PATCH 6/8] mutex: Extra reschedule point

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20140210145946.41a64fd9832b41e90c852e40@linux-foundation.org>
Date:	Mon, 10 Feb 2014 14:59:46 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	linux-kernel@...r.kernel.org, Jason Low <jason.low2@...com>,
	Waiman Long <waiman.long@...com>, mingo@...nel.org,
	paulmck@...ux.vnet.ibm.com, torvalds@...ux-foundation.org,
	tglx@...utronix.de, riel@...hat.com, davidlohr@...com,
	hpa@...or.com, andi@...stfloor.org, aswin@...com,
	scott.norton@...com, chegu_vinod@...com
Subject: Re: [PATCH 6/8] mutex: Extra reschedule point

On Mon, 10 Feb 2014 20:58:26 +0100 Peter Zijlstra <peterz@...radead.org> wrote:

> Add in an extra reschedule in an attempt to avoid getting reschedule
> the moment we've acquired the lock.
> 
> ...
>
> --- a/kernel/locking/mutex.c
> +++ b/kernel/locking/mutex.c
> @@ -468,6 +468,13 @@ __mutex_lock_common(struct mutex *lock,
>  	}
>  	osq_unlock(&lock->osq);
>  slowpath:
> +	/*
> +	 * If we fell out of the spin path because of need_resched(),
> +	 * reschedule now, before we try-lock the mutex. This avoids getting
> +	 * scheduled out right after we obtained the mutex.
> +	 */
> +	if (unlikely(need_resched()))
> +		schedule_preempt_disabled();

need_resched() already does unlikely().
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/