[3.8.y.z extended stable] Patch "virtio-net: fix refill races during restore" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    virtio-net: fix refill races during restore

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.16.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 000bedcac6e56c1bcb49bbccd86fca2485a6f75a Mon Sep 17 00:00:00 2001
From: Jason Wang <jasowang at redhat.com>
Date: Mon, 30 Dec 2013 11:34:40 +0800
Subject: virtio-net: fix refill races during restore

[ Upstream commit 6cd4ce0099da7702f885b6fa9ebb49e3831d90b4 ]

During restoring, try_fill_recv() was called with neither napi lock nor napi
disabled. This can lead two try_fill_recv() was called in the same time. Fix
this by refilling before trying to enable napi.

Fixes 0741bcb5584f9e2390ae6261573c4de8314999f2
(virtio: net: Add freeze, restore handlers to support S4).

Cc: Amit Shah <amit.shah at redhat.com>
Cc: Rusty Russell <rusty at rustcorp.com.au>
Cc: Michael S. Tsirkin <mst at redhat.com>
Cc: Eric Dumazet <eric.dumazet at gmail.com>
Signed-off-by: Jason Wang <jasowang at redhat.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
[ kamal: backport to 3.8 (context) ]
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/net/virtio_net.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 8f009899..4380036 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1723,16 +1723,17 @@ static int virtnet_restore(struct virtio_device *vdev)
 	if (err)
 		return err;

-	if (netif_running(vi->dev))
+	if (netif_running(vi->dev)) {
+		for (i = 0; i < vi->curr_queue_pairs; i++)
+			if (!try_fill_recv(&vi->rq[i], GFP_KERNEL))
+				schedule_delayed_work(&vi->refill, 0);
+
 		for (i = 0; i < vi->max_queue_pairs; i++)
 			virtnet_napi_enable(&vi->rq[i]);
+	}

 	netif_device_attach(vi->dev);

-	for (i = 0; i < vi->max_queue_pairs; i++)
-		if (!try_fill_recv(&vi->rq[i], GFP_KERNEL))
-			schedule_delayed_work(&vi->refill, 0);
-
 	mutex_lock(&vi->config_lock);
 	vi->config_enable = true;
 	mutex_unlock(&vi->config_lock);
--
1.8.3.2