ipvlan: Fix return value of ipvlan_queue_xmit()

ipvlan_queue_xmit() should return NET_XMIT_XXX, but
ipvlan_xmit_mode_l2/l3() returns rx_handler_result_t or NET_RX_XXX
in some cases. ipvlan_rcv_frame() will only return RX_HANDLER_CONSUMED
in ipvlan_xmit_mode_l2/l3() because 'local' is true. It's equal to
NET_XMIT_SUCCESS. But dev_forward_skb() can return NET_RX_SUCCESS or
NET_RX_DROP, and returning NET_RX_DROP(NET_XMIT_DROP) will increase
both ipvlan and ipvlan->phy_dev drops counter.

The skb to forward can be treated as xmitted successfully. This patch
makes ipvlan_queue_xmit() return NET_XMIT_SUCCESS for forward skb.

Fixes: 2ad7bf3 ("ipvlan: Initial check-in of the IPVLAN driver.")
Signed-off-by: Cambda Zhu <cambda@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230626093347.7492-1-cambda@linux.alibaba.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: guangmuzhu

drivers/net/ipvlan/ipvlan_core.c

@@ -585,7 +585,8 @@ static int ipvlan_xmit_mode_l3(struct sk_buff *skb, struct net_device *dev)
 				consume_skb(skb);
 				return NET_XMIT_DROP;
 			}
-			return ipvlan_rcv_frame(addr, &skb, true);
+			ipvlan_rcv_frame(addr, &skb, true);
+			return NET_XMIT_SUCCESS;
 		}
 	}
 out:
@@ -611,7 +612,8 @@ static int ipvlan_xmit_mode_l2(struct sk_buff *skb, struct net_device *dev)
 					consume_skb(skb);
 					return NET_XMIT_DROP;
 				}
-				return ipvlan_rcv_frame(addr, &skb, true);
+				ipvlan_rcv_frame(addr, &skb, true);
+				return NET_XMIT_SUCCESS;
 			}
 		}
 		skb = skb_share_check(skb, GFP_ATOMIC);
@@ -623,7 +625,8 @@ static int ipvlan_xmit_mode_l2(struct sk_buff *skb, struct net_device *dev)
 		 * the skb for the main-dev. At the RX side we just return
 		 * RX_PASS for it to be processed further on the stack.
 		 */
-		return dev_forward_skb(ipvlan->phy_dev, skb);
+		dev_forward_skb(ipvlan->phy_dev, skb);
+		return NET_XMIT_SUCCESS;
 
 	} else if (is_multicast_ether_addr(eth->h_dest)) {
 		skb_reset_mac_header(skb);