From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754631Ab1LGKX1 (ORCPT ); Wed, 7 Dec 2011 05:23:27 -0500 Received: from mx1.redhat.com ([209.132.183.28]:60755 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752518Ab1LGKX0 (ORCPT ); Wed, 7 Dec 2011 05:23:26 -0500 Date: Wed, 7 Dec 2011 12:25:08 +0200 From: "Michael S. Tsirkin" To: Amit Shah Cc: Virtualization List , Rusty Russell , levinsasha928@gmail.com, linux-kernel@vger.kernel.org Message-ID: <20111207102507.GB8326@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Pavel Machek , "Rafael J. Wysocki" , Len Brown , linux-pm@vger.kernel.org Bcc: Subject: Re: [PATCH v4 12/12] virtio: balloon: Add freeze, restore handlers to support S4 Reply-To: In-Reply-To: <5deccc36afa59032f0e3b10a653773bad511f303.1323199985.git.amit.shah@redhat.com> On Wed, Dec 07, 2011 at 01:18:50AM +0530, Amit Shah wrote: > Now to not race with a host issuing ballooning requests while we are in > the process of freezing, we just exit from the vballoon kthread when the > processes are asked to freeze. Upon thaw and restore, we re-start the > thread. ... > --- > drivers/virtio/virtio_balloon.c | 79 ++++++++++++++++++++++++++++++++++++++- > 1 files changed, 78 insertions(+), 1 deletions(-) > > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > index 8bf99be..10ec638 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/virtio/virtio_balloon.c > @@ -258,7 +258,13 @@ static int balloon(void *_vballoon) > while (!kthread_should_stop()) { > s64 diff; > > - try_to_freeze(); > + /* > + * On suspend, we want to exit this thread. We will > + * start a new thread on resume. > + */ > + if (freezing(current)) > + break; > + > wait_event_interruptible(vb->config_change, > (diff = towards_target(vb)) != 0 > || vb->need_stats_update ... Note: this relies on kthreads being frozen before devices. Looking at kernel/power/hibernate.c this is the case, but I think we should add a comment to note this. Also Cc linux-pm crowd in case I got it wrong. -- MST