[PATCH net v3 0/3] Avoid TCP resets when using ECMP for load-balancing between multiple servers.

[PATCH net v3 0/3] Avoid TCP resets when using ECMP for load-balancing between multiple servers.

[Sriram Yagnaraman]

All packets in the same flow (L3/L4 depending on multipath hash policy)
should be directed to the same target, but after [0]/[1] we see stray
packets directed towards other targets. This, for instance, causes RST
to be sent on TCP connections.

The first two patches solve the problem by ignoring route hints for
destinations that are part of multipath group, by using new SKB flags
for IPv4 and IPv6. The third patch is a selftest that tests the
scenario.

Thanks to Ido, for reviewing and suggesting a way forward in [2] and
also suggesting how to write a selftest for this.

v2->v3:
- Add NULL check for skb in fib6_select_path (Ido Schimmel)
- Use fib_tests.sh for selftest instead of the forwarding suite (Ido
  Schimmel)
v1->v2:
- Update to commit messages describing the solution (Ido Schimmel)
- Use perf stat to count fib table lookups in selftest (Ido Schimmel)


Sriram Yagnaraman (3):
  ipv4: ignore dst hint for multipath routes
  ipv6: ignore dst hint for multipath routes
  selftests: fib_tests: Add multipath list receive tests

 include/linux/ipv6.h                     |   1 +
 include/net/ip.h                         |   1 +
 net/ipv4/ip_input.c                      |   3 +-
 net/ipv4/route.c                         |   1 +
 net/ipv6/ip6_input.c                     |   3 +-
 net/ipv6/route.c                         |   3 +
 tools/testing/selftests/net/fib_tests.sh | 150 ++++++++++++++++++++++-
 7 files changed, 159 insertions(+), 3 deletions(-)

-- 
2.34.1

[PATCH net v3 1/3] ipv4: ignore dst hint for multipath routes

[Sriram Yagnaraman]

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>
---
 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 92fede388d52..33626619aee7 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
 
-- 
2.34.1

Re: [PATCH net v3 1/3] ipv4: ignore dst hint for multipath routes

[Ido Schimmel]

On Mon, Aug 28, 2023 at 01:32:19PM +0200, Sriram Yagnaraman wrote:
> 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>

Re: [PATCH net v3 1/3] ipv4: ignore dst hint for multipath routes

[David Ahern]

On 8/28/23 5:32 AM, Sriram Yagnaraman wrote:
> 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>
> ---
>  include/net/ip.h    | 1 +
>  net/ipv4/ip_input.c | 3 ++-
>  net/ipv4/route.c    | 1 +
>  3 files changed, 4 insertions(+), 1 deletion(-)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>

[PATCH net v3 2/3] ipv6: ignore dst hint for multipath routes

[Sriram Yagnaraman]

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 IP6SKB_MULTIPATH is introduced for this purpose, set the
flag when route is looked up in fib6_select_path() and use it in
ip6_can_use_hint() to check for the existence of the flag.

Fixes: 197dbf24e360 ("ipv6: introduce and uses route look hints for list input.")
Signed-off-by: Sriram Yagnaraman <sriram.yagnaraman@est.tech>
---
 include/linux/ipv6.h | 1 +
 net/ipv6/ip6_input.c | 3 ++-
 net/ipv6/route.c     | 3 +++
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 839247a4f48e..fe3492a67b35 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -146,6 +146,7 @@ struct inet6_skb_parm {
 #define IP6SKB_JUMBOGRAM      128
 #define IP6SKB_SEG6	      256
 #define IP6SKB_FAKEJUMBO      512
+#define IP6SKB_MULTIPATH      1024
 };
 
 #if defined(CONFIG_NET_L3_MASTER_DEV)
diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index d94041bb4287..b8378814532c 100644
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -99,7 +99,8 @@ static bool ip6_can_use_hint(const struct sk_buff *skb,
 static struct sk_buff *ip6_extract_route_hint(const struct net *net,
 					      struct sk_buff *skb)
 {
-	if (fib6_routes_require_src(net) || fib6_has_custom_rules(net))
+	if (fib6_routes_require_src(net) || fib6_has_custom_rules(net) ||
+	    IP6CB(skb)->flags & IP6SKB_MULTIPATH)
 		return NULL;
 
 	return skb;
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 56a55585eb79..a02328c93a53 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -424,6 +424,9 @@ void fib6_select_path(const struct net *net, struct fib6_result *res,
 	if (match->nh && have_oif_match && res->nh)
 		return;
 
+	if (skb)
+		IP6CB(skb)->flags |= IP6SKB_MULTIPATH;
+
 	/* We might have already computed the hash for ICMPv6 errors. In such
 	 * case it will always be non-zero. Otherwise now is the time to do it.
 	 */
-- 
2.34.1

Re: [PATCH net v3 2/3] ipv6: ignore dst hint for multipath routes

[Ido Schimmel]

On Mon, Aug 28, 2023 at 01:32:20PM +0200, Sriram Yagnaraman wrote:
> 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 IP6SKB_MULTIPATH is introduced for this purpose, set the
> flag when route is looked up in fib6_select_path() and use it in
> ip6_can_use_hint() to check for the existence of the flag.
> 
> Fixes: 197dbf24e360 ("ipv6: introduce and uses route look hints for list input.")
> Signed-off-by: Sriram Yagnaraman <sriram.yagnaraman@est.tech>

Reviewed-by: Ido Schimmel <idosch@nvidia.com>

Re: [PATCH net v3 2/3] ipv6: ignore dst hint for multipath routes

[David Ahern]

On 8/28/23 5:32 AM, Sriram Yagnaraman wrote:
> 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 IP6SKB_MULTIPATH is introduced for this purpose, set the
> flag when route is looked up in fib6_select_path() and use it in
> ip6_can_use_hint() to check for the existence of the flag.
> 
> Fixes: 197dbf24e360 ("ipv6: introduce and uses route look hints for list input.")
> Signed-off-by: Sriram Yagnaraman <sriram.yagnaraman@est.tech>
> ---
>  include/linux/ipv6.h | 1 +
>  net/ipv6/ip6_input.c | 3 ++-
>  net/ipv6/route.c     | 3 +++
>  3 files changed, 6 insertions(+), 1 deletion(-)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>

[PATCH net v3 3/3] selftests: fib_tests: Add multipath list receive tests

[Sriram Yagnaraman]

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 | 150 ++++++++++++++++++++++-
 1 file changed, 149 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/fib_tests.sh b/tools/testing/selftests/net/fib_tests.sh
index 35d89dfa6f11..1cf78cf4d346 100755
--- a/tools/testing/selftests/net/fib_tests.sh
+++ b/tools/testing/selftests/net/fib_tests.sh
@@ -9,7 +9,7 @@ ret=0
 ksft_skip=4
 
 # all tests in this script. Can be overridden with -t option
-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 ipv4_mangle ipv6_mangle ipv4_bcast_neigh"
+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 ipv4_mangle ipv6_mangle ipv4_bcast_neigh ipv4_mpath_list ipv6_mpath_list"
 
 VERBOSE=0
 PAUSE_ON_FAIL=no
@@ -2138,6 +2138,152 @@ 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
+}
+
+list_rcv_eval()
+{
+	local name=$1; shift
+	local file=$1; shift
+	local expected=$1; shift
+	local exp=$1; shift
+
+
+	local count=$(tail -n 1 $file | jq '.["counter-value"] | tonumber | floor')
+	local ratio=$(echo "scale=2; $count / $expected" | bc -l)
+	local res=$(echo "$ratio $exp" | bc)
+	[[ $res -eq 1 ]]
+	log_test $? 0 "$name 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.
+	run_cmd "perf stat -e fib:fib_table_lookup --filter 'err == 0' -j -o $tmp_file -- $cmd"
+	list_rcv_eval "Multipath" $tmp_file 65536 ">= 0.95"
+
+	# The same is not true for a single path route.
+	run_cmd "ip -n ns2 route replace 203.0.113.0/24 nexthop via 172.16.201.2"
+	run_cmd "perf stat -e fib:fib_table_lookup --filter 'err == 0' -j -o $tmp_file -- $cmd"
+	list_rcv_eval "Single path" $tmp_file 65536 "< 0.95"
+
+	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.
+	run_cmd "perf stat -e fib6:fib6_table_lookup --filter 'err == 0' -j -o $tmp_file -- $cmd"
+	list_rcv_eval "Multipath" $tmp_file 65536 ">= 0.95"
+
+	# The same is not true for a single path route.
+	run_cmd "ip -n ns2 route replace 2001:db8:301::/64 nexthop via 2001:db8:201::2"
+	run_cmd "perf stat -e fib6:fib6_table_lookup --filter 'err == 0' -j -o $tmp_file -- $cmd"
+	list_rcv_eval "Single path" $tmp_file 65536 "< 0.95"
+
+	rm $tmp_file
+	route_cleanup
+}
+
 ################################################################################
 # usage
 
@@ -2217,6 +2363,8 @@ do
 	ipv4_mangle)			ipv4_mangle_test;;
 	ipv6_mangle)			ipv6_mangle_test;;
 	ipv4_bcast_neigh)		ipv4_bcast_neigh_test;;
+	ipv4_mpath_list)		ipv4_mpath_list_test;;
+	ipv6_mpath_list)		ipv6_mpath_list_test;;
 
 	help) echo "Test names: $TESTS"; exit 0;;
 	esac
-- 
2.34.1

Re: [PATCH net v3 3/3] selftests: fib_tests: Add multipath list receive tests

[Ido Schimmel]

On Mon, Aug 28, 2023 at 01:32:21PM +0200, Sriram Yagnaraman wrote:
> 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>

I just tested this with a debug config and noticed that the single path
test is not very stable. It's not really related to the bug fix, so I
think you can simply remove it.

Jakub / Paolo, this change conflicts with changes in net-next and I
assume that the next PR that you are going to send is from net-next.
What is your preference in this case? Wait for the PR to be accepted and
for master to be merged into net?

Thanks

Re: [PATCH net v3 3/3] selftests: fib_tests: Add multipath list receive tests

[David Ahern]

On 8/28/23 9:24 AM, Ido Schimmel wrote:
> On Mon, Aug 28, 2023 at 01:32:21PM +0200, Sriram Yagnaraman wrote:
>> 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>
> 
> I just tested this with a debug config and noticed that the single path
> test is not very stable. It's not really related to the bug fix, so I
> think you can simply remove it.
> 
> Jakub / Paolo, this change conflicts with changes in net-next and I
> assume that the next PR that you are going to send is from net-next.
> What is your preference in this case? Wait for the PR to be accepted and
> for master to be merged into net?
> 
> Thanks

Ido, thanks for staying on top of this change and the details with the
test cases.

Re: [PATCH net v3 3/3] selftests: fib_tests: Add multipath list receive tests

[Jakub Kicinski]

On Mon, 28 Aug 2023 18:24:20 +0300 Ido Schimmel wrote:
> Jakub / Paolo, this change conflicts with changes in net-next and I
> assume that the next PR that you are going to send is from net-next.
> What is your preference in this case? Wait for the PR to be accepted and
> for master to be merged into net?

The trees will be merged before the PR, in the next 24h.
As soon as they are you can resend for net-next.

RE: [PATCH net v3 3/3] selftests: fib_tests: Add multipath list receive tests

[Sriram Yagnaraman]

> -----Original Message-----
> From: Ido Schimmel <idosch@idosch.org>
> Sent: Monday, 28 August 2023 17:24
> To: Sriram Yagnaraman <sriram.yagnaraman@est.tech>; kuba@kernel.org;
> pabeni@redhat.com
> Cc: netdev@vger.kernel.org; linux-kselftest@vger.kernel.org; David S . Miller
> <davem@davemloft.net>; Eric Dumazet <edumazet@google.com>; Jakub
> Kicinski <kuba@kernel.org>; Paolo Abeni <pabeni@redhat.com>; David Ahern
> <dsahern@kernel.org>; Ido Schimmel <idosch@nvidia.com>; Shuah Khan
> <shuah@kernel.org>; Petr Machata <petrm@nvidia.com>
> Subject: Re: [PATCH net v3 3/3] selftests: fib_tests: Add multipath list receive
> tests
> 
> On Mon, Aug 28, 2023 at 01:32:21PM +0200, Sriram Yagnaraman wrote:
> > 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>
> 
> I just tested this with a debug config and noticed that the single path test is not
> very stable. It's not really related to the bug fix, so I think you can simply
> remove it.
> 

Sent v4 with just the multipath test and rebased to latest after the merge with net-next. 

If it is OK with all of you here, should I try to improve this test to verify TCP resets don't happen when the nexthop is in a multipath group, perhaps using iperf3? I can send another patch if/when I get something working.

Re: [PATCH net v3 3/3] selftests: fib_tests: Add multipath list receive tests

[Ido Schimmel]

On Wed, Aug 30, 2023 at 09:17:22AM +0000, Sriram Yagnaraman wrote:
> If it is OK with all of you here, should I try to improve this test to verify TCP resets don't happen when the nexthop is in a multipath group, perhaps using iperf3? I can send another patch if/when I get something working.

Yes, just make sure it's stable. That is, the test reliably fails
without the fixes and reliably passes with the fixes.

Re: [PATCH net v3 2/3] ipv6: ignore dst hint for multipath routes

[kernel test robot]

In-Reply-To: <20230828113221.20123-3-sriram.yagnaraman@est.tech>
References: <20230828113221.20123-3-sriram.yagnaraman@est.tech>
TO: Sriram Yagnaraman <sriram.yagnaraman@est.tech>
CC: netdev@vger.kernel.org
CC: linux-kselftest@vger.kernel.org
CC: "David S . Miller" <davem@davemloft.net>
CC: Eric Dumazet <edumazet@google.com>
CC: Jakub Kicinski <kuba@kernel.org>
CC: Paolo Abeni <pabeni@redhat.com>
CC: David Ahern <dsahern@kernel.org>
CC: Ido Schimmel <idosch@nvidia.com>
CC: Shuah Khan <skhan@linuxfoundation.org>
CC: Petr Machata <petrm@nvidia.com>
CC: Sriram Yagnaraman <sriram.yagnaraman@est.tech>

Hi Sriram,

kernel test robot noticed the following build errors:

[auto build test ERROR on net/main]

url:    https://github.com/intel-lab-lkp/linux/commits/Sriram-Yagnaraman/ipv4-ignore-dst-hint-for-multipath-routes/20230828-203216
base:   net/main
patch link:    https://lore.kernel.org/r/20230828113221.20123-3-sriram.yagnaraman%40est.tech
patch subject: [PATCH net v3 2/3] ipv6: ignore dst hint for multipath routes
config: riscv-randconfig-r033-20230829 (https://download.01.org/0day-ci/archive/20230829/202308291103.hzyzyCB5-lkp@intel.com/config)
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project.git f28c006a5895fc0e329fe15fead81e37457cb1d1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230829/202308291103.hzyzyCB5-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202308291103.hzyzyCB5-lkp@intel.com/

All errors (new ones prefixed by >>):

>> ld.lld: error: vmlinux.a(init/main.o):(function do_one_initcall: .text+0xc1c): relocation R_RISCV_HI20 out of range: 529094 is not in [-524288, 524287]; references .L.str.17
   >>> referenced by main.c
   >>> defined in vmlinux.a(init/main.o)
--
>> ld.lld: error: vmlinux.a(init/main.o):(function perf_trace_initcall_level: .text+0x3d8): relocation R_RISCV_HI20 out of range: 531219 is not in [-524288, 524287]; references __per_cpu_offset
   >>> referenced by main.c
   >>> defined in vmlinux.a(mm/percpu.o)
--
>> ld.lld: error: vmlinux.a(init/main.o):(function perf_trace_initcall_start: .text+0x620): relocation R_RISCV_HI20 out of range: 531219 is not in [-524288, 524287]; references __per_cpu_offset
   >>> referenced by main.c
   >>> defined in vmlinux.a(mm/percpu.o)
--
>> ld.lld: error: vmlinux.a(init/main.o):(function perf_trace_initcall_finish: .text+0x848): relocation R_RISCV_HI20 out of range: 531219 is not in [-524288, 524287]; references __per_cpu_offset
   >>> referenced by main.c
   >>> defined in vmlinux.a(mm/percpu.o)
--
>> ld.lld: error: vmlinux.a(init/main.o):(function rcu_read_unlock: .text+0x9b8): relocation R_RISCV_HI20 out of range: 529605 is not in [-524288, 524287]; references rcu_lock_map
   >>> referenced by main.c
   >>> defined in vmlinux.a(kernel/rcu/update.o)

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki