igb: refactor XDP registration

On changing the RX ring parameters igb uses a hack to avoid a warning
when calling xdp_rxq_info_reg via igb_setup_rx_resources.  It just
clears the struct xdp_rxq_info content.

Instead, change this to unregister if we're already registered.  Align
code to the igc code.

Fixes: 9cbc948 ("igb: add XDP support")
Signed-off-by: Corinna Vinschen <vinschen@redhat.com>
Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Tested-by: Sandeep Penigalapati <sandeep.penigalapati@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/igb/igb_ethtool.c

@@ -965,10 +965,6 @@ static int igb_set_ringparam(struct net_device *netdev,
 			memcpy(&temp_ring[i], adapter->rx_ring[i],
 			       sizeof(struct igb_ring));
 
-			/* Clear copied XDP RX-queue info */
-			memset(&temp_ring[i].xdp_rxq, 0,
-			       sizeof(temp_ring[i].xdp_rxq));
-
 			temp_ring[i].count = new_rx_count;
 			err = igb_setup_rx_resources(&temp_ring[i]);
 			if (err) {

drivers/net/ethernet/intel/igb/igb_main.c

@@ -4345,7 +4345,18 @@ int igb_setup_rx_resources(struct igb_ring *rx_ring)
 {
 	struct igb_adapter *adapter = netdev_priv(rx_ring->netdev);
 	struct device *dev = rx_ring->dev;
-	int size;
+	int size, res;
+
+	/* XDP RX-queue info */
+	if (xdp_rxq_info_is_reg(&rx_ring->xdp_rxq))
+		xdp_rxq_info_unreg(&rx_ring->xdp_rxq);
+	res = xdp_rxq_info_reg(&rx_ring->xdp_rxq, rx_ring->netdev,
+			       rx_ring->queue_index, 0);
+	if (res < 0) {
+		dev_err(dev, "Failed to register xdp_rxq index %u\n",
+			rx_ring->queue_index);
+		return res;
+	}
 
 	size = sizeof(struct igb_rx_buffer) * rx_ring->count;
 
@@ -4368,14 +4379,10 @@ int igb_setup_rx_resources(struct igb_ring *rx_ring)
 
 	rx_ring->xdp_prog = adapter->xdp_prog;
 
-	/* XDP RX-queue info */
-	if (xdp_rxq_info_reg(&rx_ring->xdp_rxq, rx_ring->netdev,
-			     rx_ring->queue_index, 0) < 0)
-		goto err;
-
 	return 0;
 
 err:
+	xdp_rxq_info_unreg(&rx_ring->xdp_rxq);
 	vfree(rx_ring->rx_buffer_info);
 	rx_ring->rx_buffer_info = NULL;
 	dev_err(dev, "Unable to allocate memory for the Rx descriptor ring\n");