linux-kernel - Re: [RFC PATCH] rtmutex: Do not prio boost when timeout is used

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: <20140426110437.GK26782@laptop.programming.kicks-ass.net>
Date:	Sat, 26 Apr 2014 13:04:37 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	linux-rt-users <linux-rt-users@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>
Subject: Re: [RFC PATCH] rtmutex: Do not prio boost when timeout is used

On Fri, Apr 25, 2014 at 04:28:48PM -0400, Steven Rostedt wrote:
> I've been discussing an issue on IRC with deadlock checking and found
> something wrong with it. Mainly, if any of the locks have a timeout,
> then even if the chain loops, there is no real deadlock. If one of the
> locks in the chain times out, then things will move forward again.


POSIX (opengroup):

 http://pubs.opengroup.org/onlinepubs/009695399/functions/pthread_mutex_timedlock.html

Explicitly states that pthread_mutex_timedlock() should participate in
the PI chain, it also states that its perfectly valid for this function
to return -EDEADLK.

Therefore, there's nothing wrong. If this behaviour breaks userspace,
its already broken for not actually expecting the right thing.
--
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/