linux-kernel - [PATCH net-next v2] xen-netback: Fix vif->disable handling

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Message-ID: <1407415118-16365-1-git-send-email-zoltan.kiss@citrix.com>
Date:	Thu, 7 Aug 2014 13:38:38 +0100
From:	Zoltan Kiss <zoltan.kiss@...rix.com>
To:	Wei Liu <wei.liu2@...rix.com>,
	Ian Campbell <Ian.Campbell@...rix.com>
CC:	Zoltan Kiss <zoltan.kiss@...rix.com>,
	David Vrabel <david.vrabel@...rix.com>,
	<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<xen-devel@...ts.xenproject.org>
Subject: [PATCH net-next v2] xen-netback: Fix vif->disable handling

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@...rix.com>
Signed-off-by: David Vrabel <david.vrabel@...rix.com>
Cc: netdev@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Cc: xen-devel@...ts.xenproject.org
---
v2: fix a code style error in this "if" as well

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index aa20933..4734472 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -2025,9 +2025,15 @@ int xenvif_kthread_guest_rx(void *data)
 		 * context so we defer it here, if this thread is
 		 * associated with queue 0.
 		 */
-		if (unlikely(queue->vif->disabled && queue->id == 0))
+		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)) {
--
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