drivers: net: loopback: Optimize packet drop

If we are dropping packets, then drop then early without the clone, this
improves zperf performance.

Signed-off-by: Krishna T <[email protected]>

Author: Krishna T

drivers/net/loopback.c

@@ -89,6 +89,19 @@ static int loopback_send(const struct device *dev, struct net_pkt *pkt)
 
 	ARG_UNUSED(dev);
 
+#ifdef CONFIG_NET_LOOPBACK_SIMULATE_PACKET_DROP
+	/* Drop packets based on the loopback_packet_drop_ratio
+	 * a ratio of 0.2 will drop one every 5 packets
+	 */
+	loopback_packet_drop_state += loopback_packet_drop_ratio;
+	if (loopback_packet_drop_state >= 1.0f) {
+		/* Administrate we dropped a packet */
+		loopback_packet_drop_state -= 1.0f;
+		loopback_packet_dropped_count++;
+		return 0;
+	}
+#endif
+
 	if (!pkt->frags) {
 		LOG_ERR("No data to send");
 		return -ENODATA;
@@ -125,24 +138,6 @@ static int loopback_send(const struct device *dev, struct net_pkt *pkt)
 		goto out;
 	}
 
-#ifdef CONFIG_NET_LOOPBACK_SIMULATE_PACKET_DROP
-	/* Drop packets based on the loopback_packet_drop_ratio
-	 * a ratio of 0.2 will drop one every 5 packets
-	 */
-	loopback_packet_drop_state += loopback_packet_drop_ratio;
-	if (loopback_packet_drop_state >= 1.0f) {
-		/* Administrate we dropped a packet */
-		loopback_packet_drop_state -= 1.0f;
-		loopback_packet_dropped_count++;
-
-		/* Clean up the packet */
-		net_pkt_unref(cloned);
-		/* Pretend everything was fine */
-		res = 0;
-
-		goto out;
-	}
-#endif
 	res = net_recv_data(net_pkt_iface(cloned), cloned);
 	if (res < 0) {
 		LOG_ERR("Data receive failed.");