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@kernel.org>
Link: https://patch.msgid.link/20250915091958.15382-3-atenart@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 8878e865ddf6cd45c8e746060d014b2e5e2e1026..93b8286e526a582ff25f3b3d74f6895392e75e19 100644 (file)
--- 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) {