Pavel Machek <pavel@xxxxxx>,
"Rafael J. Wysocki" <rjw@xxxxxxx>,
Len Brown <len.brown@xxxxxxxxx>,
linux-pm@xxxxxxxxxxxxxxx
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@xxxxxxxxxx>
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
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