linux-kernel - Re: [PATCH v6 09/11] virtio: net: Add freeze, restore handlers to support S4

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Date:	Thu, 29 Dec 2011 18:15:23 +0200
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	Amit Shah <amit.shah@...hat.com>
Cc:	Virtualization List <virtualization@...ts.linux-foundation.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v6 09/11] virtio: net: Add freeze, restore handlers to
 support S4

On Thu, Dec 22, 2011 at 04:58:33PM +0530, Amit Shah wrote:
> Remove all the vqs, disable napi and detach from the netdev on
> hibernation.
> 
> Re-create vqs after restoring from a hibernated image, re-enable napi
> and re-attach the netdev.  This keeps networking working across
> hibernation.
> 
> Signed-off-by: Amit Shah <amit.shah@...hat.com>
> ---
>  drivers/net/virtio_net.c |   46 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 46 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 7a2a5bf..b31670f 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1159,6 +1159,48 @@ static void __devexit virtnet_remove(struct virtio_device *vdev)
>  	free_netdev(vi->dev);
>  }
>  
> +#ifdef CONFIG_PM
> +static int virtnet_freeze(struct virtio_device *vdev)
> +{
> +	struct virtnet_info *vi = vdev->priv;
> +
> +	virtqueue_disable_cb(vi->rvq);
> +	virtqueue_disable_cb(vi->svq);
> +	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ))
> +		virtqueue_disable_cb(vi->cvq);
> +
> +	netif_device_detach(vi->dev);
> +	cancel_delayed_work_sync(&vi->refill);
> +
> +	if (netif_running(vi->dev))
> +		napi_disable(&vi->napi);
> +
> +	remove_vq_common(vi);
> +
> +	return 0;
> +}
> +
> +static int virtnet_restore(struct virtio_device *vdev)
> +{
> +	struct virtnet_info *vi = vdev->priv;
> +	int err;
> +
> +	err = init_vqs(vi);
> +	if (err)
> +		return err;
> +
> +	if (netif_running(vi->dev))

Can virtnet close run at this point?
If yes it's a bug.

> +		virtnet_napi_enable(vi);
> +
> +	netif_device_attach(vi->dev);
> +

Not that open/close start/stop refill,
I wonder whether this is a problem.
For example, can virtnet_close run at this point,
and cancel refill?

> +	if (!try_fill_recv(vi, GFP_KERNEL))
> +		schedule_delayed_work(&vi->refill, 0);

This needs to be switched to non reentrant wq too?

> +
> +	return 0;
> +}
> +#endif
> +
>  static struct virtio_device_id id_table[] = {
>  	{ VIRTIO_ID_NET, VIRTIO_DEV_ANY_ID },
>  	{ 0 },
> @@ -1183,6 +1225,10 @@ static struct virtio_driver virtio_net_driver = {
>  	.probe =	virtnet_probe,
>  	.remove =	__devexit_p(virtnet_remove),
>  	.config_changed = virtnet_config_changed,
> +#ifdef CONFIG_PM
> +	.freeze =	virtnet_freeze,
> +	.restore =	virtnet_restore,
> +#endif
>  };
>  
>  static int __init init(void)
> -- 
> 1.7.7.4
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