From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:54566)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <m.gibula@beyond.pl>) id 1XEKqz-0007wl-2o
	for qemu-devel@nongnu.org; Mon, 04 Aug 2014 12:11:22 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <m.gibula@beyond.pl>) id 1XEKqt-0002nm-Mx
	for qemu-devel@nongnu.org; Mon, 04 Aug 2014 12:11:17 -0400
Received: from mx.beyond.pl ([92.43.117.49]:57343)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <m.gibula@beyond.pl>) id 1XEKqt-0002kv-Fq
	for qemu-devel@nongnu.org; Mon, 04 Aug 2014 12:11:11 -0400
Message-ID: <53DFB084.9040405@beyond.pl>
Date: Mon, 04 Aug 2014 18:10:44 +0200
From: =?UTF-8?B?TWFyY2luIEdpYnXFgmE=?= <m.gibula@beyond.pl>
MIME-Version: 1.0
References: <1407167793-20425-1-git-send-email-stefanha@redhat.com>
In-Reply-To: <1407167793-20425-1-git-send-email-stefanha@redhat.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: quoted-printable
Subject: Re: [Qemu-devel] [PATCH] linux-aio: avoid deadlock in nested
 aio_poll() calls
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Stefan Hajnoczi <stefanha@redhat.com>, qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Ming Lei <ming.lei@canonical.com>

W dniu 2014-08-04 17:56, Stefan Hajnoczi pisze:
> If two Linux AIO request completions are fetched in the same
> io_getevents() call, QEMU will deadlock if request A's callback waits
> for request B to complete using an aio_poll() loop.  This was reported
> to happen with the mirror blockjob.

s/mirror/commit/

> This patch moves completion processing into a BH and makes it resumable=
.
> Nested event loops can resume completion processing so that request B
> will complete and the deadlock will not occur.
>
> Cc: Kevin Wolf <kwolf@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Ming Lei <ming.lei@canonical.com>
> Cc: Marcin Gibu=C5=82a <m.gibula@beyond.pl>
> Reported-by: Marcin Gibu=C5=82a <m.gibula@beyond.pl>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

I'll test it tomorrow.

--=20
mg