From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1N8yC4-0008KI-C8
	for qemu-devel@nongnu.org; Fri, 13 Nov 2009 10:36:12 -0500
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1N8yBz-0008Jk-Ma
	for qemu-devel@nongnu.org; Fri, 13 Nov 2009 10:36:12 -0500
Received: from [199.232.76.173] (port=39100 helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1N8yBz-0008Jf-FC
	for qemu-devel@nongnu.org; Fri, 13 Nov 2009 10:36:07 -0500
Received: from mail-pw0-f43.google.com ([209.85.160.43]:48708)
	by monty-python.gnu.org with esmtp (Exim 4.60)
	(envelope-from <scottt.tw@gmail.com>) id 1N8yBz-0004rg-4H
	for qemu-devel@nongnu.org; Fri, 13 Nov 2009 10:36:07 -0500
Received: by pwi12 with SMTP id 12so2158493pwi.2
	for <qemu-devel@nongnu.org>; Fri, 13 Nov 2009 07:36:05 -0800 (PST)
MIME-Version: 1.0
In-Reply-To: <1258125436-23759-1-git-send-email-kwolf@redhat.com>
References: <1258125436-23759-1-git-send-email-kwolf@redhat.com>
Date: Fri, 13 Nov 2009 23:36:05 +0800
Message-ID: <ef2f888d0911130736u18686ae3u631f9e97d1592357@mail.gmail.com>
Subject: Re: [Qemu-devel] [PATCH] Don't leak file descriptors
From: Scott Tsai <scottt.tw@gmail.com>
Content-Type: text/plain; charset=UTF-8
List-Id: qemu-devel.nongnu.org
List-Unsubscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/pipermail/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Kevin Wolf <kwolf@redhat.com>
Cc: qemu-devel@nongnu.org

On Fri, Nov 13, 2009 at 11:17 PM, Kevin Wolf <kwolf@redhat.com> wrote:
> We're leaking file descriptors to child processes. Set FD_CLOEXEC on file
> descriptors that don't need to be passed to children to stop this misbehaviour.

Since qemu is a multi threaded program, how about opening those file
descriptors with the equivalent of O_CLOEXEC set to avoid the race
condition when a fork comes between the 'open/socket/accept' operation
and the 'fcntl'?

We could create helper functions like 'qemu_socket_cloexec'.
The implementation of qemu_socket_cloexec would use the new system
calls and flags listed in:
http://udrepper.livejournal.com/20407.html
if available and fall back to separate 'open' and 'fcnt' operations
when not building with a new enough glibc.