net: ena: Don't register memory info on XDP exchange

Since the queues aren't destroyed when we only exchange XDP programs,
there's no need to re-register them again.

Fixes: 548c4940 ("net: ena: Implement XDP_TX action")
Signed-off-by: NShay Agroskin <shayagr@amazon.com>
Signed-off-by: NDavid Arinzon <darinzon@amazon.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/amazon/ena/ena_netdev.c

@@ -512,16 +512,18 @@ static void ena_xdp_exchange_program_rx_in_range(struct ena_adapter *adapter,
 						 struct bpf_prog *prog,
 						 int first, int count)
 {
+	struct bpf_prog *old_bpf_prog;
 	struct ena_ring *rx_ring;
 	int i = 0;
 
 	for (i = first; i < count; i++) {
 		rx_ring = &adapter->rx_ring[i];
-		xchg(&rx_ring->xdp_bpf_prog, prog);
-		if (prog) {
+		old_bpf_prog = xchg(&rx_ring->xdp_bpf_prog, prog);
+
+		if (!old_bpf_prog && prog) {
 			ena_xdp_register_rxq_info(rx_ring);
 			rx_ring->rx_headroom = XDP_PACKET_HEADROOM;
-		} else {
+		} else if (old_bpf_prog && !prog) {
 			ena_xdp_unregister_rxq_info(rx_ring);
 			rx_ring->rx_headroom = NET_SKB_PAD;
 		}