linux-kernel - Re: [PATCH net 1/2] virtio-net: don't respond to cpu hotplug notifier if we're not ready

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Message-ID: <20131014110621.GF30954@redhat.com>
Date:	Mon, 14 Oct 2013 14:06:21 +0300
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	Jason Wang <jasowang@...hat.com>
Cc:	virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, rusty@...tcorp.com.au,
	Wanlong Gao <gaowanlong@...fujitsu.com>
Subject: Re: [PATCH net 1/2] virtio-net: don't respond to cpu hotplug
 notifier if we're not ready

On Mon, Oct 14, 2013 at 05:56:34PM +0800, Jason Wang wrote:
> We're trying to re-configure the affinity unconditionally in cpu hotplug
> callback. This may lead the issue during resuming from s3/s4 since
> 
> - virt queues haven't been allocated at that time.
> - it's unnecessary since thaw method will re-configure the affinity.
> 
> Fix this issue by checking the config_enable and do nothing is we're not ready.
> 
> The bug were introduced by commit 8de4b2f3ae90c8fc0f17eeaab87d5a951b66ee17
> (virtio-net: reset virtqueue affinity when doing cpu hotplug).
> 
> Cc: Rusty Russell <rusty@...tcorp.com.au>
> Cc: Michael S. Tsirkin <mst@...hat.com>
> Cc: Wanlong Gao <gaowanlong@...fujitsu.com>
> Signed-off-by: Jason Wang <jasowang@...hat.com>

Acked-by: Michael S. Tsirkin <mst@...hat.com>

> ---
> The patch is need for 3.8 and above.
> ---
>  drivers/net/virtio_net.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index defec2b..c4bc1cc 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1116,6 +1116,11 @@ static int virtnet_cpu_callback(struct notifier_block *nfb,
>  {
>  	struct virtnet_info *vi = container_of(nfb, struct virtnet_info, nb);
>  
> +	mutex_lock(&vi->config_lock);
> +
> +	if (!vi->config_enable)
> +		goto done;
> +
>  	switch(action & ~CPU_TASKS_FROZEN) {
>  	case CPU_ONLINE:
>  	case CPU_DOWN_FAILED:
> @@ -1128,6 +1133,9 @@ static int virtnet_cpu_callback(struct notifier_block *nfb,
>  	default:
>  		break;
>  	}
> +
> +done:
> +	mutex_unlock(&vi->config_lock);
>  	return NOTIFY_OK;
>  }
>  
> -- 
> 1.8.1.2
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