netdev - [PATCH net-next 2/3] net: ipv4: simplify drop reason handling in ip_rcv_finish

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Message-ID: <20250915091958.15382-3-atenart@kernel.org>
Date: Mon, 15 Sep 2025 11:19:55 +0200
From: Antoine Tenart <atenart@...nel.org>
To: davem@...emloft.net,
	kuba@...nel.org,
	pabeni@...hat.com,
	edumazet@...gle.com
Cc: Antoine Tenart <atenart@...nel.org>,
	netdev@...r.kernel.org
Subject: [PATCH net-next 2/3] net: ipv4: simplify drop reason handling in ip_rcv_finish_core

Instead of setting the drop reason to SKB_DROP_REASON_NOT_SPECIFIED
early and having to reset it each time it is overridden by a function
returned value, just set the drop reason to the expected value before
returning from ip_rcv_finish_core.

Signed-off-by: Antoine Tenart <atenart@...nel.org>
---
 net/ipv4/ip_input.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 8878e865ddf6..93b8286e526a 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -335,7 +335,6 @@ static int ip_rcv_finish_core(struct net *net,
 			goto drop_error;
 	}
 
-	drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
 	if (READ_ONCE(net->ipv4.sysctl_ip_early_demux) &&
 	    !skb_dst(skb) &&
 	    !skb->sk &&
@@ -354,7 +353,6 @@ static int ip_rcv_finish_core(struct net *net,
 				drop_reason = udp_v4_early_demux(skb);
 				if (unlikely(drop_reason))
 					goto drop_error;
-				drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
 
 				/* must reload iph, skb->head might have changed */
 				iph = ip_hdr(skb);
@@ -372,7 +370,6 @@ static int ip_rcv_finish_core(struct net *net,
 						   ip4h_dscp(iph), dev);
 		if (unlikely(drop_reason))
 			goto drop_error;
-		drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
 	} else {
 		struct in_device *in_dev = __in_dev_get_rcu(dev);
 
@@ -391,8 +388,10 @@ static int ip_rcv_finish_core(struct net *net,
 	}
 #endif
 
-	if (iph->ihl > 5 && ip_rcv_options(skb, dev))
+	if (iph->ihl > 5 && ip_rcv_options(skb, dev)) {
+		drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
 		goto drop;
+	}
 
 	rt = skb_rtable(skb);
 	if (rt->rt_type == RTN_MULTICAST) {
-- 
2.51.0