Route hints when the nexthop is part of a multipath group causes packets in the same receive batch to be sent to the same nexthop irrespective of the multipath hash of the packet. So, do not extract route hint for packets whose destination is part of a multipath group.

A new SKB flag IPSKB_MULTIPATH is introduced for this purpose, set the flag when route is looked up in ip_mkroute_input() and use it in ip_extract_route_hint() to check for the existence of the flag.

Fixes: 02b24941619f ("ipv4: use dst hint for ipv4 list receive") Signed-off-by: Sriram Yagnaraman sriram.yagnaraman@est.tech Reviewed-by: Ido Schimmel idosch@nvidia.com Reviewed-by: David Ahern dsahern@kernel.org --- include/net/ip.h | 1 + net/ipv4/ip_input.c | 3 ++- net/ipv4/route.c | 1 + 3 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/net/ip.h b/include/net/ip.h index 19adacd5ece0..464176a88f86 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -57,6 +57,7 @@ struct inet_skb_parm { #define IPSKB_FRAG_PMTU BIT(6) #define IPSKB_L3SLAVE BIT(7) #define IPSKB_NOPOLICY BIT(8) +#define IPSKB_MULTIPATH BIT(9)

u16 frag_max_size; }; diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c index fe9ead9ee863..5e9c8156656a 100644 --- a/net/ipv4/ip_input.c +++ b/net/ipv4/ip_input.c @@ -584,7 +584,8 @@ 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) { - if (fib4_has_custom_rules(net) || rt_type == RTN_BROADCAST) + if (fib4_has_custom_rules(net) || rt_type == RTN_BROADCAST || + IPCB(skb)->flags & IPSKB_MULTIPATH) return NULL;

return skb; diff --git a/net/ipv4/route.c b/net/ipv4/route.c index a4e153dd615b..6a3f57a3fa41 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -2144,6 +2144,7 @@ static int ip_mkroute_input(struct sk_buff *skb, int h = fib_multipath_hash(res->fi->fib_net, NULL, skb, hkeys);

fib_select_multipath(res, h); + IPCB(skb)->flags |= IPSKB_MULTIPATH; } #endif

The test uses perf stat to count the number of fib:fib_table_lookup tracepoint hits for IPv4 and the number of fib6:fib6_table_lookup for IPv6. The measured count is checked to be within 5% of the total number of packets sent via veth1.

Signed-off-by: Sriram Yagnaraman sriram.yagnaraman@est.tech --- tools/testing/selftests/net/fib_tests.sh | 155 ++++++++++++++++++++++- 1 file changed, 154 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/fib_tests.sh b/tools/testing/selftests/net/fib_tests.sh index d328af4a149c..e7d2a530618a 100755 --- a/tools/testing/selftests/net/fib_tests.sh +++ b/tools/testing/selftests/net/fib_tests.sh @@ -12,7 +12,8 @@ ksft_skip=4 TESTS="unregister down carrier nexthop suppress ipv6_notify ipv4_notify \ ipv6_rt ipv4_rt ipv6_addr_metric ipv4_addr_metric ipv6_route_metrics \ ipv4_route_metrics ipv4_route_v6_gw rp_filter ipv4_del_addr \ - ipv6_del_addr ipv4_mangle ipv6_mangle ipv4_bcast_neigh fib6_gc_test" + ipv6_del_addr ipv4_mangle ipv6_mangle ipv4_bcast_neigh fib6_gc_test \ + ipv4_mpath_list ipv6_mpath_list"

VERBOSE=0 PAUSE_ON_FAIL=no @@ -2352,6 +2353,156 @@ ipv4_bcast_neigh_test() cleanup }

+mpath_dep_check() +{ + if [ ! -x "$(command -v mausezahn)" ]; then + echo "mausezahn command not found. Skipping test" + return 1 + fi + + if [ ! -x "$(command -v jq)" ]; then + echo "jq command not found. Skipping test" + return 1 + fi + + if [ ! -x "$(command -v bc)" ]; then + echo "bc command not found. Skipping test" + return 1 + fi + + if [ ! -x "$(command -v perf)" ]; then + echo "perf command not found. Skipping test" + return 1 + fi + + perf list fib:* | grep -q fib_table_lookup + if [ $? -ne 0 ]; then + echo "IPv4 FIB tracepoint not found. Skipping test" + return 1 + fi + + perf list fib6:* | grep -q fib6_table_lookup + if [ $? -ne 0 ]; then + echo "IPv6 FIB tracepoint not found. Skipping test" + return 1 + fi + + return 0 +} + +link_stats_get() +{ + local ns=$1; shift + local dev=$1; shift + local dir=$1; shift + local stat=$1; shift + + ip -n $ns -j -s link show dev $dev \ + | jq '.[]["stats64"]["'$dir'"]["'$stat'"]' +} + +list_rcv_eval() +{ + local file=$1; shift + local expected=$1; shift + + local count=$(tail -n 1 $file | jq '.["counter-value"] | tonumber | floor') + local ratio=$(echo "scale=2; $count / $expected" | bc -l) + local res=$(echo "$ratio >= 0.95" | bc) + [[ $res -eq 1 ]] + log_test $? 0 "Multipath route hit ratio ($ratio)" +} + +ipv4_mpath_list_test() +{ + echo + echo "IPv4 multipath list receive tests" + + mpath_dep_check || return 1 + + route_setup + + set -e + run_cmd "ip netns exec ns1 ethtool -K veth1 tcp-segmentation-offload off" + + run_cmd "ip netns exec ns2 bash -c "echo 20000 > /sys/class/net/veth2/gro_flush_timeout"" + run_cmd "ip netns exec ns2 bash -c "echo 1 > /sys/class/net/veth2/napi_defer_hard_irqs"" + run_cmd "ip netns exec ns2 ethtool -K veth2 generic-receive-offload on" + run_cmd "ip -n ns2 link add name nh1 up type dummy" + run_cmd "ip -n ns2 link add name nh2 up type dummy" + run_cmd "ip -n ns2 address add 172.16.201.1/24 dev nh1" + run_cmd "ip -n ns2 address add 172.16.202.1/24 dev nh2" + run_cmd "ip -n ns2 neigh add 172.16.201.2 lladdr 00:11:22:33:44:55 nud perm dev nh1" + run_cmd "ip -n ns2 neigh add 172.16.202.2 lladdr 00:aa:bb:cc:dd:ee nud perm dev nh2" + run_cmd "ip -n ns2 route add 203.0.113.0/24 + nexthop via 172.16.201.2 nexthop via 172.16.202.2" + run_cmd "ip netns exec ns2 sysctl -qw net.ipv4.fib_multipath_hash_policy=1" + set +e + + local dmac=$(ip -n ns2 -j link show dev veth2 | jq -r '.[]["address"]') + local tmp_file=$(mktemp) + local cmd="ip netns exec ns1 mausezahn veth1 -a own -b $dmac + -A 172.16.101.1 -B 203.0.113.1 -t udp 'sp=12345,dp=0-65535' -q" + + # Packets forwarded in a list using a multipath route must not reuse a + # cached result so that a flow always hits the same nexthop. In other + # words, the FIB lookup tracepoint needs to be triggered for every + # packet. + local t0_rx_pkts=$(link_stats_get ns2 veth2 rx packets) + run_cmd "perf stat -e fib:fib_table_lookup --filter 'err == 0' -j -o $tmp_file -- $cmd" + local t1_rx_pkts=$(link_stats_get ns2 veth2 rx packets) + local diff=$(echo $t1_rx_pkts - $t0_rx_pkts | bc -l) + list_rcv_eval $tmp_file $diff + + rm $tmp_file + route_cleanup +} + +ipv6_mpath_list_test() +{ + echo + echo "IPv6 multipath list receive tests" + + mpath_dep_check || return 1 + + route_setup + + set -e + run_cmd "ip netns exec ns1 ethtool -K veth1 tcp-segmentation-offload off" + + run_cmd "ip netns exec ns2 bash -c "echo 20000 > /sys/class/net/veth2/gro_flush_timeout"" + run_cmd "ip netns exec ns2 bash -c "echo 1 > /sys/class/net/veth2/napi_defer_hard_irqs"" + run_cmd "ip netns exec ns2 ethtool -K veth2 generic-receive-offload on" + run_cmd "ip -n ns2 link add name nh1 up type dummy" + run_cmd "ip -n ns2 link add name nh2 up type dummy" + run_cmd "ip -n ns2 -6 address add 2001:db8:201::1/64 dev nh1" + run_cmd "ip -n ns2 -6 address add 2001:db8:202::1/64 dev nh2" + run_cmd "ip -n ns2 -6 neigh add 2001:db8:201::2 lladdr 00:11:22:33:44:55 nud perm dev nh1" + run_cmd "ip -n ns2 -6 neigh add 2001:db8:202::2 lladdr 00:aa:bb:cc:dd:ee nud perm dev nh2" + run_cmd "ip -n ns2 -6 route add 2001:db8:301::/64 + nexthop via 2001:db8:201::2 nexthop via 2001:db8:202::2" + run_cmd "ip netns exec ns2 sysctl -qw net.ipv6.fib_multipath_hash_policy=1" + set +e + + local dmac=$(ip -n ns2 -j link show dev veth2 | jq -r '.[]["address"]') + local tmp_file=$(mktemp) + local cmd="ip netns exec ns1 mausezahn -6 veth1 -a own -b $dmac + -A 2001:db8:101::1 -B 2001:db8:301::1 -t udp 'sp=12345,dp=0-65535' -q" + + # Packets forwarded in a list using a multipath route must not reuse a + # cached result so that a flow always hits the same nexthop. In other + # words, the FIB lookup tracepoint needs to be triggered for every + # packet. + local t0_rx_pkts=$(link_stats_get ns2 veth2 rx packets) + run_cmd "perf stat -e fib6:fib6_table_lookup --filter 'err == 0' -j -o $tmp_file -- $cmd" + local t1_rx_pkts=$(link_stats_get ns2 veth2 rx packets) + local diff=$(echo $t1_rx_pkts - $t0_rx_pkts | bc -l) + list_rcv_eval $tmp_file $diff + + rm $tmp_file + route_cleanup +} + ################################################################################ # usage

@@ -2433,6 +2584,8 @@ do ipv6_mangle) ipv6_mangle_test;; ipv4_bcast_neigh) ipv4_bcast_neigh_test;; fib6_gc_test|ipv6_gc) fib6_gc_test;; + ipv4_mpath_list) ipv4_mpath_list_test;; + ipv6_mpath_list) ipv6_mpath_list_test;;

help) echo "Test names: $TESTS"; exit 0;; esac