[3.8.y.z extended stable] Patch "virtio-net: don't respond to cpu hotplug notifier if we're not ready" has been added to staging queue

Kamal Mostafa kamal at canonical.com
Fri Nov 1 21:43:41 UTC 2013

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

    virtio-net: don't respond to cpu hotplug notifier if we're not ready

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


This patch is scheduled to be released in version

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



>From ee42dca9358c110c126d4b1ff1e1d0e427911364 Mon Sep 17 00:00:00 2001
From: Jason Wang <jasowang at redhat.com>
Date: Tue, 15 Oct 2013 11:18:58 +0800
Subject: virtio-net: don't respond to cpu hotplug notifier if we're not ready

[ Upstream commit 3ab098df35f8b98b6553edc2e40234af512ba877 ]

We're trying to re-configure the affinity unconditionally in cpu hotplug
callback. This may lead the issue during resuming from s3/s4 since

- virt queues haven't been allocated at that time.
- it's unnecessary since thaw method will re-configure the affinity.

Fix this issue by checking the config_enable and do nothing is we're not ready.

The bug were introduced by commit 8de4b2f3ae90c8fc0f17eeaab87d5a951b66ee17
(virtio-net: reset virtqueue affinity when doing cpu hotplug).

Cc: Rusty Russell <rusty at rustcorp.com.au>
Cc: Michael S. Tsirkin <mst at redhat.com>
Cc: Wanlong Gao <gaowanlong at cn.fujitsu.com>
Acked-by: Michael S. Tsirkin <mst at redhat.com>
Reviewed-by: Wanlong Gao <gaowanlong at cn.fujitsu.com>
Signed-off-by: Jason Wang <jasowang at redhat.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 drivers/net/virtio_net.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 35c00c5..848d26c 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1076,6 +1076,11 @@ static int virtnet_cpu_callback(struct notifier_block *nfb,
 	struct virtnet_info *vi = container_of(nfb, struct virtnet_info, nb);

+	mutex_lock(&vi->config_lock);
+	if (!vi->config_enable)
+		goto done;
 	switch(action & ~CPU_TASKS_FROZEN) {
 	case CPU_ONLINE:
@@ -1088,6 +1093,9 @@ static int virtnet_cpu_callback(struct notifier_block *nfb,
+	mutex_unlock(&vi->config_lock);
 	return NOTIFY_OK;


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