Commit 1b8c5fa0 authored by Oscar Maes's avatar Oscar Maes Committed by Jakub Kicinski
Browse files

net: ipv4: allow directed broadcast routes to use dst hint 



Currently, ip_extract_route_hint uses RTN_BROADCAST to decide
whether to use the route dst hint mechanism.

This check is too strict, as it prevents directed broadcast
routes from using the hint, resulting in poor performance
during bursts of directed broadcast traffic.

Fix this in ip_extract_route_hint and modify ip_route_use_hint
to preserve the intended behaviour.

Signed-off-by: default avatarOscar Maes <oscmaes92@gmail.com>
Reviewed-by: default avatarDavid Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20250819174642.5148-2-oscmaes92@gmail.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 7f052126

net/ipv4/ip_input.c

+7 −4
Original line number Diff line number Diff line
@@ -587,9 +587,13 @@ static void ip_sublist_rcv_finish(struct list_head *head) 
}



static struct sk_buff *ip_extract_route_hint(const struct net *net,

					     struct sk_buff *skb, int rt_type)

					     struct sk_buff *skb)

{

	if (fib4_has_custom_rules(net) || rt_type == RTN_BROADCAST ||

	const struct iphdr *iph = ip_hdr(skb);



	if (fib4_has_custom_rules(net) ||

	    ipv4_is_lbcast(iph->daddr) ||

	    ipv4_is_zeronet(iph->daddr) ||

	    IPCB(skb)->flags & IPSKB_MULTIPATH)

		return NULL;
@@ -618,8 +622,7 @@ static void ip_list_rcv_finish(struct net *net, struct list_head *head) 


		dst = skb_dst(skb);

		if (curr_dst != dst) {

			hint = ip_extract_route_hint(net, skb,

						     dst_rtable(dst)->rt_type);

			hint = ip_extract_route_hint(net, skb);



			/* dispatch old sublist */

			if (!list_empty(&sublist))

net/ipv4/route.c

+1 −1
Original line number Diff line number Diff line
@@ -2210,7 +2210,7 @@ ip_route_use_hint(struct sk_buff *skb, __be32 daddr, __be32 saddr, 
		goto martian_source;

	}



	if (rt->rt_type != RTN_LOCAL)

	if (!(rt->rt_flags & RTCF_LOCAL))

		goto skip_validate_source;



	reason = fib_validate_source_reason(skb, saddr, daddr, dscp, 0, dev,