linux-kernel - Re: [PATCH] posix clocks: replace mutex with reader/writer semaphore

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: <alpine.LFD.2.00.1103301541000.22418@localhost6.localdomain6>
Date:	Wed, 30 Mar 2011 15:41:40 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Richard Cochran <richardcochran@...il.com>
cc:	linux-kernel@...r.kernel.org, John Stultz <john.stultz@...aro.org>
Subject: Re: [PATCH] posix clocks: replace mutex with reader/writer
 semaphore

On Wed, 30 Mar 2011, Richard Cochran wrote:

> A dynamic posix clock is protected from asynchronous removal by a mutex.
> However, using a mutex has the unwanted effect that a long running clock
> operation in one process will unnecessarily block other processes.
> 
> For example, one process might call read() to get an external time stamp
> coming in at one pulse per second. A second process calling clock_gettime
> would have to wait for almost a whole second.
> 
> This patch fixes the issue by using a reader/writer semaphore instead of
> a mutex.

Yuck. /me wonders why we did not see that during the review :)
 
--
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/