From owner-freebsd-threads@FreeBSD.ORG  Wed Sep  8 17:56:11 2010
Return-Path: <owner-freebsd-threads@FreeBSD.ORG>
Delivered-To: freebsd-threads@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 3F9A71065672;
	Wed,  8 Sep 2010 17:56:11 +0000 (UTC) (envelope-from jilles@stack.nl)
Received: from mx1.stack.nl (relay02.stack.nl [IPv6:2001:610:1108:5010::104])
	by mx1.freebsd.org (Postfix) with ESMTP id 065338FC12;
	Wed,  8 Sep 2010 17:56:11 +0000 (UTC)
Received: from turtle.stack.nl (turtle.stack.nl [IPv6:2001:610:1108:5010::132])
	by mx1.stack.nl (Postfix) with ESMTP id DC8CE35A838;
	Wed,  8 Sep 2010 19:56:09 +0200 (CEST)
Received: by turtle.stack.nl (Postfix, from userid 1677)
	id D0DBB17248; Wed,  8 Sep 2010 19:56:09 +0200 (CEST)
Date: Wed, 8 Sep 2010 19:56:09 +0200
From: Jilles Tjoelker <jilles@stack.nl>
To: David Xu <davidxu@freebsd.org>
Message-ID: <20100908175609.GA30144@stack.nl>
References: <20100906220041.GA4729@stack.nl>
 <4C86787E.6070908@freebsd.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <4C86787E.6070908@freebsd.org>
User-Agent: Mutt/1.5.20 (2009-06-14)
Cc: freebsd-threads@freebsd.org
Subject: Re: sigwait() cancellation point
X-BeenThere: freebsd-threads@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Threading on FreeBSD <freebsd-threads.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-threads>, 
	<mailto:freebsd-threads-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-threads>
List-Post: <mailto:freebsd-threads@freebsd.org>
List-Help: <mailto:freebsd-threads-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-threads>,
	<mailto:freebsd-threads-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 08 Sep 2010 17:56:11 -0000

On Tue, Sep 07, 2010 at 05:38:06PM +0000, David Xu wrote:
> Jilles Tjoelker wrote:
> > Our sigwait() implementation may not be POSIX-compliant as it returns
> > EINTR when it is interrupted by a caught signal. (Unfortunately I can
> > only find this in SUSv4 in the Rationale, B.2.3 Error Numbers,
> > Disallowing Return of the [EINTR] Error Code; the sigwait() page in XSH
> > does not list an [EINTR] error condition, but does not prohibit one
> > either like pthread_mutex_lock() and various others do.)

> A system call can not return EINTR is not flexible, I think why don't
> we fix it in libc and libthr, but let kernel returns EINTR?

> I have worked out a patch:

> http://people.freebsd.org/~davidxu/patch/sigwait.diff

The idea and patch seem sensible. Some man page changes seem in order
though: sigwaitinfo.2 should mention this difference between sigwait()
and sigwaitinfo() more explicitly.

-- 
Jilles Tjoelker