On Wed, 2010-08-11 at 04:19 +0100, Xu, Dongxiao wrote:
> From 791fc8ed6e2888af3bd398f22562776c757cc4ac Mon Sep 17 00:00:00 2001
> From: Dongxiao Xu <dongxiao.xu@xxxxxxxxx>
> Date: Wed, 11 Aug 2010 11:06:06 +0800
> Subject: [PATCH] Netfront: Fix save/restore after enabled smart poll
> feature
>
> When s/r the guest, the shared ring will be set to NULL, and
> in this case the polling timer interrupt should stop.
>
> This fix includes the two parts:
> 1) Stop hrtimer when guest suspends.
> 2) Add check to avoid NULL pointer dereference.
Looks good to me but do you really need 2) given 1)?
Ian.
>
> Thanks Ian J for reporting the problem.
>
> Signed-off-by: Dongxiao Xu <dongxiao.xu@xxxxxxxxx>
> ---
> drivers/net/xen-netfront.c | 13 +++++++++++++
> 1 files changed, 13 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
> index 328fe40..eaea132 100644
> --- a/drivers/net/xen-netfront.c
> +++ b/drivers/net/xen-netfront.c
> @@ -1289,6 +1289,14 @@ static void xennet_disconnect_backend(struct
> netfront_info *info)
> info->rx.sring = NULL;
> }
>
> +static int netfront_suspend(struct xenbus_device *dev, pm_message_t
> state)
> +{
> + struct netfront_info *info = dev_get_drvdata(&dev->dev);
> + struct hrtimer *timer = &info->smart_poll.timer;
> + hrtimer_cancel(timer);
> + return 0;
> +}
> +
> /**
> * We are reconnecting to the backend, due to a suspend/resume, or a
> backend
> * driver restart. We tear down our netif structure and recreate it,
> but
> @@ -1340,6 +1348,10 @@ static enum hrtimer_restart
> smart_poll_function(struct hrtimer *timer)
> np = netdev_priv(dev);
>
> spin_lock_irqsave(&np->tx_lock, flags);
> +
> + if (!np->rx.sring)
> + goto end;
> +
> np->smart_poll.counter++;
>
> if (likely(netif_carrier_ok(dev))) {
> @@ -1910,6 +1922,7 @@ static struct xenbus_driver netfront_driver = {
> .ids = netfront_ids,
> .probe = netfront_probe,
> .remove = __devexit_p(xennet_remove),
> + .suspend = netfront_suspend,
> .resume = netfront_resume,
> .otherend_changed = netback_changed,
> };
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