virtio_net: check virtqueue_add_sgs() return value

As virtqueue_add_sgs() can fail, we should check the return value.

Addresses-Coverity-ID: 1464439 ("Unchecked return value")
Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/virtio_net.c

@@ -1743,6 +1743,7 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
 {
 	struct scatterlist *sgs[4], hdr, stat;
 	unsigned out_num = 0, tmp;
+	int ret;
 
 	/* Caller should know better */
 	BUG_ON(!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ));
@@ -1762,7 +1763,12 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
 	sgs[out_num] = &stat;
 
 	BUG_ON(out_num + 1 > ARRAY_SIZE(sgs));
-	virtqueue_add_sgs(vi->cvq, sgs, out_num, 1, vi, GFP_ATOMIC);
+	ret = virtqueue_add_sgs(vi->cvq, sgs, out_num, 1, vi, GFP_ATOMIC);
+	if (ret < 0) {
+		dev_warn(&vi->vdev->dev,
+			 "Failed to add sgs for command vq: %d\n.", ret);
+		return false;
+	}
 
 	if (unlikely(!virtqueue_kick(vi->cvq)))
 		return vi->ctrl->status == VIRTIO_NET_OK;