linux-kernel - Re: [PATCH for 3.12] mutex: Avoid gcc version dependent __builtin_constant

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: <525FC1DD.4030205@canonical.com>
Date:	Thu, 17 Oct 2013 12:54:21 +0200
From:	Maarten Lankhorst <maarten.lankhorst@...onical.com>
To:	Peter Zijlstra <peterz@...radead.org>,
	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
CC:	mingo@...nel.org, imirkin@...m.mit.edu,
	linux-kernel@...r.kernel.org, daniel.vetter@...ll.ch,
	robdclark@...il.com
Subject: Re: [PATCH for 3.12] mutex: Avoid gcc version dependent __builtin_constant_p()
 usage.

op 17-10-13 12:52, Peter Zijlstra schreef:
> On Thu, Oct 17, 2013 at 07:45:29PM +0900, Tetsuo Handa wrote:
>> Commit 040a0a37 "mutex: Add support for wound/wait style locks" used
>> "!__builtin_constant_p(p == NULL)" but gcc 3.x cannot handle such expression
>> correctly, leading to boot failure when built with CONFIG_DEBUG_MUTEXES=y.
> So I completely forgot all about this, but wouldn't something like:
>
>  !(__builtin_constant_p(p) && p == NULL)
>
> Not also work and generate the same code?
>
See earlier discussion. It was already answered why that was undesirable. ;)

~Maarten
--
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/