Commit 3ad96554 authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

Merge branch 'net-ipv4-allow-directed-broadcast-routes-to-use-dst-hint' 

Oscar Maes says:

====================
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.

This series fixes this, and adds a new selftest to ensure
this does not regress.

Link to v2: https://lore.kernel.org/20250814140309.3742-1-oscmaes92@gmail.com
====================

Link: https://patch.msgid.link/20250819174642.5148-1-oscmaes92@gmail.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parents 7f052126 bd0d9e75

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,

tools/testing/selftests/net/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -117,6 +117,7 @@ TEST_GEN_FILES += tfo 
TEST_PROGS += tfo_passive.sh

TEST_PROGS += broadcast_pmtu.sh

TEST_PROGS += ipv6_force_forwarding.sh

TEST_PROGS += route_hint.sh



# YNL files, must be before "include ..lib.mk"

YNL_GEN_FILES := busy_poller netlink-dumps

tools/testing/selftests/net/route_hint.sh

0 → 100755
+79 −0
Original line number Diff line number Diff line 
#!/bin/bash

# SPDX-License-Identifier: GPL-2.0



# This test ensures directed broadcast routes use dst hint mechanism



source lib.sh



CLIENT_IP4="192.168.0.1"

SERVER_IP4="192.168.0.2"

BROADCAST_ADDRESS="192.168.0.255"



setup() {

	setup_ns CLIENT_NS SERVER_NS



	ip -net "${SERVER_NS}" link add link1 type veth peer name link0 netns "${CLIENT_NS}"



	ip -net "${CLIENT_NS}" link set link0 up

	ip -net "${CLIENT_NS}" addr add "${CLIENT_IP4}/24" dev link0



	ip -net "${SERVER_NS}" link set link1 up

	ip -net "${SERVER_NS}" addr add "${SERVER_IP4}/24" dev link1



	ip netns exec "${CLIENT_NS}" ethtool -K link0 tcp-segmentation-offload off

	ip netns exec "${SERVER_NS}" sh -c "echo 500000000 > /sys/class/net/link1/gro_flush_timeout"

	ip netns exec "${SERVER_NS}" sh -c "echo 1 > /sys/class/net/link1/napi_defer_hard_irqs"

	ip netns exec "${SERVER_NS}" ethtool -K link1 generic-receive-offload on

}



cleanup() {

	ip -net "${SERVER_NS}" link del link1

	cleanup_ns "${CLIENT_NS}" "${SERVER_NS}"

}



directed_bcast_hint_test()

{

	local rc=0



	echo "Testing for directed broadcast route hint"



	orig_in_brd=$(ip netns exec "${SERVER_NS}" lnstat -j -i1 -c1 | jq '.in_brd')

	ip netns exec "${CLIENT_NS}" mausezahn link0 -a own -b bcast -A "${CLIENT_IP4}" \

		-B "${BROADCAST_ADDRESS}" -c1 -t tcp "sp=1-100,dp=1234,s=1,a=0" -p 5 -q

	sleep 1

	new_in_brd=$(ip netns exec "${SERVER_NS}" lnstat -j -i1 -c1 | jq '.in_brd')



	res=$(echo "${new_in_brd} - ${orig_in_brd}" | bc)



	if [ "${res}" -lt 100 ]; then

		echo "[ OK ]"

		rc="${ksft_pass}"

	else

		echo "[FAIL] expected in_brd to be under 100, got ${res}"

		rc="${ksft_fail}"

	fi



	return "${rc}"

}



if [ ! -x "$(command -v mausezahn)" ]; then

	echo "SKIP: Could not run test without mausezahn tool"

	exit "${ksft_skip}"

fi



if [ ! -x "$(command -v jq)" ]; then

	echo "SKIP: Could not run test without jq tool"

	exit "${ksft_skip}"

fi



if [ ! -x "$(command -v bc)" ]; then

	echo "SKIP: Could not run test without bc tool"

	exit "${ksft_skip}"

fi



trap cleanup EXIT



setup



directed_bcast_hint_test

exit $?