[PATCH net-next] xen-netback: Fix vif->disable handling

[PATCH net-next] xen-netback: Fix vif->disable handling

[Zoltan Kiss]

In the patch called "xen-netback: Turn off the carrier if the guest is not able
to receive" new branches were introduced to this if statement, risking that a
queue with non-zero id can reenable the disabled interface.

Signed-off-by: Zoltan Kiss <zoltan.kiss@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: xen-devel@lists.xenproject.org

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index aa20933..f84516f 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -2027,7 +2027,13 @@ int xenvif_kthread_guest_rx(void *data)
 		 */
 		if (unlikely(queue->vif->disabled && queue->id == 0))
 			xenvif_carrier_off(queue->vif);
-		else if (unlikely(test_and_clear_bit(QUEUE_STATUS_RX_PURGE_EVENT,
+		else if (unlikely(queue->vif->disabled)) {
+			/* kthread_stop() would be called upon this thread soon,
+			 * be a bit proactive
+			 */
+			skb_queue_purge(&queue->rx_queue);
+			queue->rx_last_skb_slots = 0;
+		} else if (unlikely(test_and_clear_bit(QUEUE_STATUS_RX_PURGE_EVENT,
 						     &queue->status))) {
 			xenvif_rx_purge_event(queue);
 		} else if (!netif_carrier_ok(queue->vif->dev)) {

Re: [PATCH net-next] xen-netback: Fix vif->disable handling

[Sergei Shtylyov]

Hello.

On 08/06/2014 11:33 PM, Zoltan Kiss wrote:

> In the patch called "xen-netback: Turn off the carrier if the guest is not able
> to receive" new branches were introduced to this if statement, risking that a
> queue with non-zero id can reenable the disabled interface.

> Signed-off-by: Zoltan Kiss <zoltan.kiss@citrix.com>
> Signed-off-by: David Vrabel <david.vrabel@citrix.com>
> Cc: netdev@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Cc: xen-devel@lists.xenproject.org

> diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
> index aa20933..f84516f 100644
> --- a/drivers/net/xen-netback/netback.c
> +++ b/drivers/net/xen-netback/netback.c
> @@ -2027,7 +2027,13 @@ int xenvif_kthread_guest_rx(void *data)
>   		 */
>   		if (unlikely(queue->vif->disabled && queue->id == 0))
>   			xenvif_carrier_off(queue->vif);
> -		else if (unlikely(test_and_clear_bit(QUEUE_STATUS_RX_PURGE_EVENT,
> +		else if (unlikely(queue->vif->disabled)) {

    Perhaps it's time to fix the coding style and add {} around the first arm 
of the *if* statement?

> +			/* kthread_stop() would be called upon this thread soon,
> +			 * be a bit proactive
> +			 */
> +			skb_queue_purge(&queue->rx_queue);
> +			queue->rx_last_skb_slots = 0;
> +		} else if (unlikely(test_and_clear_bit(QUEUE_STATUS_RX_PURGE_EVENT,
>   						     &queue->status))) {
>   			xenvif_rx_purge_event(queue);
>   		} else if (!netif_carrier_ok(queue->vif->dev)) {

WBR, Sergei

Re: [PATCH net-next] xen-netback: Fix vif->disable handling

[David Miller]

From: Zoltan Kiss <zoltan.kiss@citrix.com>
Date: Wed, 6 Aug 2014 20:33:18 +0100

> In the patch called "xen-netback: Turn off the carrier if the guest is not able
> to receive" new branches were introduced to this if statement, risking that a
> queue with non-zero id can reenable the disabled interface.
> 
> Signed-off-by: Zoltan Kiss <zoltan.kiss@citrix.com>
> Signed-off-by: David Vrabel <david.vrabel@citrix.com>

Can you please resubmit this with curly braces added to the first if()'s
basic block?

Thanks.