Linux Virtualization - Apr 2017 - [PATCH net-next] virtio-net: on tx, only call napi_disable if tx napi is on

From: Willem de Bruijn <willemb at google.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 at redhat.com>
Signed-off-by: Willem de Bruijn <willemb at google.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

On Tue, Apr 25, 2017 at 03:59:17PM -0400, Willem de Bruijn
wrote:
> From: Willem de Bruijn <willemb at google.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 at redhat.com>
> Signed-off-by: Willem de Bruijn <willemb at google.com>
Acked-by: Michael S. Tsirkin <mst at redhat.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

On 2017?04?26? 03:59, Willem de Bruijn wrote:
> From: Willem de Bruijn <willemb at google.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 at redhat.com>
> Signed-off-by: Willem de Bruijn <willemb at google.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);
>   		}
>   	}
>   }
Acked-by: Jason Wang <jasowang at redhat.com>

Thanks

From: Willem de Bruijn <willemdebruijn.kernel at gmail.com>
Date: Tue, 25 Apr 2017 15:59:17 -0400
> From: Willem de Bruijn <willemb at google.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 at redhat.com>
> Signed-off-by: Willem de Bruijn <willemb at google.com>
Applied, thanks.