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Commit 9b9cd802 authored by Jason Wang's avatar Jason Wang Committed by Rusty Russell
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virtio-net: fix the race between channels setting and refill 



Commit 55257d72 (virtio-net: fill only rx queues
which are being used) tries to refill on demand when changing the number of
channels by call try_refill_recv() directly, this may race:

- the refill work who may do the refill in the same time
- the try_refill_recv() called in bh since napi was not disabled

Which may led guest complain during setting channels:

virtio_net virtio0: input.1:id 0 is not a head!

Solve this issue by scheduling a refill work which can guarantee the
serialization of refill.

Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 0d69a65e

drivers/net/virtio_net.c

+1 −4
Original line number Original line Diff line number Diff line
@@ -900,7 +900,6 @@ static int virtnet_set_queues(struct virtnet_info *vi, u16 queue_pairs) 
	struct scatterlist sg;

	struct scatterlist sg;

	struct virtio_net_ctrl_mq s;

	struct virtio_net_ctrl_mq s;

	struct net_device *dev = vi->dev;

	struct net_device *dev = vi->dev;

	int i;





	if (!vi->has_cvq || !virtio_has_feature(vi->vdev, VIRTIO_NET_F_MQ))

	if (!vi->has_cvq || !virtio_has_feature(vi->vdev, VIRTIO_NET_F_MQ))

		return 0;

		return 0;
@@ -914,10 +913,8 @@ static int virtnet_set_queues(struct virtnet_info *vi, u16 queue_pairs) 
			 queue_pairs);

			 queue_pairs);

		return -EINVAL;

		return -EINVAL;

	} else {

	} else {

		for (i = vi->curr_queue_pairs; i < queue_pairs; i++)

			if (!try_fill_recv(&vi->rq[i], GFP_KERNEL))

				schedule_delayed_work(&vi->refill, 0);

		vi->curr_queue_pairs = queue_pairs;

		vi->curr_queue_pairs = queue_pairs;

		schedule_delayed_work(&vi->refill, 0);

	}

	}





	return 0;

	return 0;