virtio-net: fix race between set queues and probe

A race were found where set_channels could be called after registering
but before virtnet_set_queues() in virtnet_probe(). Fixing this by
moving the virtnet_set_queues() before netdevice registering. While at
it, use _virtnet_set_queues() to avoid holding rtnl as the device is
not even registered at that time.

Cc: stable@vger.kernel.org
Fixes: a220871 ("virtio-net: correctly enable multiqueue")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230725072049.617289-1-jasowang@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/virtio_net.c

@@ -4219,6 +4219,8 @@ static int virtnet_probe(struct virtio_device *vdev)
 	if (vi->has_rss || vi->has_rss_hash_report)
 		virtnet_init_default_rss(vi);
 
+	_virtnet_set_queues(vi, vi->curr_queue_pairs);
+
 	/* serialize netdev register + virtio_device_ready() with ndo_open() */
 	rtnl_lock();
 
@@ -4257,8 +4259,6 @@ static int virtnet_probe(struct virtio_device *vdev)
 		goto free_unregister_netdev;
 	}
 
-	virtnet_set_queues(vi, vi->curr_queue_pairs);
-
 	/* Assume link up if device can't report link status,
 	   otherwise get link status from config. */
 	netif_carrier_off(dev);