From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([208.118.235.92]:39065)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <stefanha@redhat.com>) id 1Tgqda-0005TZ-FA
	for qemu-devel@nongnu.org; Fri, 07 Dec 2012 00:38:17 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <stefanha@redhat.com>) id 1TgqdX-0002ky-3O
	for qemu-devel@nongnu.org; Fri, 07 Dec 2012 00:38:14 -0500
Received: from mx1.redhat.com ([209.132.183.28]:65105)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <stefanha@redhat.com>) id 1TgqdW-0002kl-S8
	for qemu-devel@nongnu.org; Fri, 07 Dec 2012 00:38:11 -0500
Date: Thu, 6 Dec 2012 15:03:56 +0100
From: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20121206140356.GC2241@stefanha-thinkpad.muc.redhat.com>
References: <1354740430-22452-1-git-send-email-stefanha@redhat.com>
	<1354740430-22452-11-git-send-email-stefanha@redhat.com>
	<50C04ADB.9040402@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <50C04ADB.9040402@redhat.com>
Subject: Re: [Qemu-devel] [PATCH v5 10/11] dataplane: add virtio-blk data
	plane code
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: Paolo Bonzini <pbonzini@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Anthony Liguori <aliguori@us.ibm.com>, "Michael S. Tsirkin" <mst@redhat.com>, qemu-devel@nongnu.org, Blue Swirl <blauwirbel@gmail.com>, khoa@us.ibm.com, asias@redhat.com

On Thu, Dec 06, 2012 at 08:35:55AM +0100, Paolo Bonzini wrote:
> Il 05/12/2012 21:47, Stefan Hajnoczi ha scritto:
> > +
> > +/* Block until pending requests have completed
> > + *
> > + * The vring continues to be serviced so ensure no new requests will be added
> > + * to avoid races.
> > + */
> > +void virtio_blk_data_plane_drain(VirtIOBlockDataPlane *s)
> > +{
> > +    qemu_mutex_lock(&s->num_reqs_lock);
> > +    while (s->num_reqs > 0) {
> > +        qemu_cond_wait(&s->no_reqs_cond, &s->num_reqs_lock);
> > +    }
> > +    qemu_mutex_unlock(&s->num_reqs_lock);
> > +}
> 
> Hi Stefan,
> 
> so this was not changed from v4?

It's unchanged.  From the v5 cover letter:

 * Note I did not get rid of the mutex+condvar approach to draining
   requests.  I've had good feedback on the performance of the patch
   series so I'm not worried about eliminating the lock (it's very
   rarely contended).  Hope Michael and Paolo are okay with this
   approach.

Stefan