netdev - Re: [PATCH net-next] virtio-net: on tx, only call napi

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Date:   Tue, 25 Apr 2017 23:44:42 +0300
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc:     netdev@...r.kernel.org, jasowang@...hat.com,
        virtualization@...ts.linux-foundation.org, davem@...emloft.net,
        Willem de Bruijn <willemb@...gle.com>
Subject: Re: [PATCH net-next] virtio-net: on tx, only call napi_disable if tx
 napi is on

On Tue, Apr 25, 2017 at 03:59:17PM -0400, Willem de Bruijn wrote:
> From: Willem de Bruijn <willemb@...gle.com>
> 
> As of tx napi, device down (`ip link set dev $dev down`) hangs unless
> tx napi is enabled. Else napi_enable is not called, so napi_disable
> will spin on test_and_set_bit NAPI_STATE_SCHED.
> 
> Only call napi_disable if tx napi is enabled.
> 
> Fixes: 5a719c2552ca ("virtio-net: transmit napi")
> Reported-by: Jason Wang <jasowang@...hat.com>
> Signed-off-by: Willem de Bruijn <willemb@...gle.com>

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



> ---
>  drivers/net/virtio_net.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 003143835766..82f1c3a73345 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -997,6 +997,12 @@ static void virtnet_napi_tx_enable(struct virtnet_info *vi,
>  	return virtnet_napi_enable(vq, napi);
>  }
>  
> +static void virtnet_napi_tx_disable(struct napi_struct *napi)
> +{
> +	if (napi->weight)
> +		napi_disable(napi);
> +}
> +
>  static void refill_work(struct work_struct *work)
>  {
>  	struct virtnet_info *vi =
> @@ -1445,7 +1451,7 @@ static int virtnet_close(struct net_device *dev)
>  
>  	for (i = 0; i < vi->max_queue_pairs; i++) {
>  		napi_disable(&vi->rq[i].napi);
> -		napi_disable(&vi->sq[i].napi);
> +		virtnet_napi_tx_disable(&vi->sq[i].napi);
>  	}
>  
>  	return 0;
> @@ -1803,7 +1809,7 @@ static void virtnet_freeze_down(struct virtio_device *vdev)
>  	if (netif_running(vi->dev)) {
>  		for (i = 0; i < vi->max_queue_pairs; i++) {
>  			napi_disable(&vi->rq[i].napi);
> -			napi_disable(&vi->sq[i].napi);
> +			virtnet_napi_tx_disable(&vi->sq[i].napi);
>  		}
>  	}
>  }
> -- 
> 2.13.0.rc0.306.g87b477812d-goog