virtio_net: Fix error code in __virtnet_get_hw_stats()

The virtnet_send_command_reply() function returns true on success or
false on failure.  The "ok" variable is true/false depending on whether
it succeeds or not.  It's up to the caller to translate the true/false
into -EINVAL on failure or zero for success.

The bug is that __virtnet_get_hw_stats() returns false for both
errors and success.  It's not a bug, but it is confusing that the caller
virtnet_get_hw_stats() uses an "ok" variable to store negative error
codes.

Fix the bug and clean things up so that it's clear that
__virtnet_get_hw_stats() returns zero on success or negative error codes
on failure.

Fixes: 941168f ("virtio_net: support device stats")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Signed-off-by: NipaLocal <nipa@local>

drivers/net/virtio_net.c

@@ -4015,7 +4015,7 @@ static int __virtnet_get_hw_stats(struct virtnet_info *vi,
 					&sgs_out, &sgs_in);
 
 	if (!ok)
-		return ok;
+		return -EINVAL;
 
 	for (p = reply; p - reply < res_size; p += le16_to_cpu(hdr->size)) {
 		hdr = p;
@@ -4052,7 +4052,7 @@ static int virtnet_get_hw_stats(struct virtnet_info *vi,
 	struct virtio_net_ctrl_queue_stats *req;
 	bool enable_cvq;
 	void *reply;
-	int ok;
+	int err;
 
 	if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_DEVICE_STATS))
 		return 0;
@@ -4099,12 +4099,12 @@ static int virtnet_get_hw_stats(struct virtnet_info *vi,
 	if (enable_cvq)
 		virtnet_make_stat_req(vi, ctx, req, vi->max_queue_pairs * 2, &j);
 
-	ok = __virtnet_get_hw_stats(vi, ctx, req, sizeof(*req) * j, reply, res_size);
+	err = __virtnet_get_hw_stats(vi, ctx, req, sizeof(*req) * j, reply, res_size);
 
 	kfree(req);
 	kfree(reply);
 
-	return ok;
+	return err;
 }
 
 static void virtnet_get_strings(struct net_device *dev, u32 stringset, u8 *data)