* [PATCH net-next v4 1/2] bareudp: Enable BIG TCP packets
2026-10-11 10:20 [PATCH net-next v4 0/2] bareudp: Enable BIG TCP packets Haishuang Yan
@ 2026-10-11 10:20 ` Haishuang Yan
2026-10-16 19:10 ` Simon Horman
2026-10-11 10:20 ` [PATCH net-next v4 2/2] selftests: net: big_tcp_tunnels: Cover bareudp Haishuang Yan
1 sibling, 1 reply; 5+ messages in thread
From: Haishuang Yan @ 2026-10-11 10:20 UTC (permalink / raw)
To: netdev
Cc: Andrew Lunn, David S . Miller, Eric Dumazet, Jakub Kicinski,
Paolo Abeni, Simon Horman, Shuah Khan, Alice Mikityanska,
Daniel Borkmann, linux-kselftest, linux-kernel, Haishuang Yan
Commit f3d0f753f066 ("vxlan: Enable BIG TCP packets") and commit
03ebe91b0f61 ("geneve: Enable BIG TCP packets") allowed BIG TCP on vxlan
and geneve, after the preceding patches of that series made the common
UDP tunnel transmit path handle GSO packets larger than 64KB.
bareudp transmits through the same helpers, udp_tunnel_handle_offloads()
followed by udp_tunnel_xmit_skb() or udp_tunnel6_xmit_skb(), and does
not fill in any length field itself. Bump tso_max_size up to
GSO_MAX_SIZE so that the admin can use BIG TCP with bareudp too.
The default gso_max_size and gso_ipv4_max_size stay at 64KB, so nothing
changes unless they are raised explicitly.
iperf3 TCP over bareudp (ethertype ipv4, IPv4 outer) between two netns
connected by veth, MTU 1600 on veth, 3 runs of 20 seconds each. This
was measured in a QEMU TCG guest, so only the relative numbers are
meaningful:
gso_max_size/gso_ipv4_max_size 65536:
4380.6, 4404.2, 4354.5 Mbit/s, average 4379.8 Mbit/s
gso_max_size/gso_ipv4_max_size 196608:
5509.4, 5454.7, 5497.4 Mbit/s, average 5487.2 Mbit/s (+25%)
With 196608, about 90k to 100k packets larger than 64KB were
transmitted on the bareudp device per run, none with 65536. Without
this patch, setting gso_max_size to 196608 is rejected.
Assisted-by: LLM
Acked-by: Alice Mikityanska <alice.kernel@fastmail.im>
Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
---
drivers/net/bareudp.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/net/bareudp.c b/drivers/net/bareudp.c
index c3b5ed52d877..fcc33e302b9c 100644
--- a/drivers/net/bareudp.c
+++ b/drivers/net/bareudp.c
@@ -589,6 +589,7 @@ static void bareudp_setup(struct net_device *dev)
dev->max_mtu = IP_MAX_MTU - BAREUDP_BASE_HLEN;
dev->type = ARPHRD_NONE;
netif_keep_dst(dev);
+ netif_set_tso_max_size(dev, GSO_MAX_SIZE);
dev->priv_flags |= IFF_NO_QUEUE;
dev->lltx = true;
dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
--
2.43.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH net-next v4 2/2] selftests: net: big_tcp_tunnels: Cover bareudp
2026-10-11 10:20 [PATCH net-next v4 0/2] bareudp: Enable BIG TCP packets Haishuang Yan
2026-10-11 10:20 ` [PATCH net-next v4 1/2] " Haishuang Yan
@ 2026-10-11 10:20 ` Haishuang Yan
2026-10-16 19:11 ` Simon Horman
1 sibling, 1 reply; 5+ messages in thread
From: Haishuang Yan @ 2026-10-11 10:20 UTC (permalink / raw)
To: netdev
Cc: Andrew Lunn, David S . Miller, Eric Dumazet, Jakub Kicinski,
Paolo Abeni, Simon Horman, Shuah Khan, Alice Mikityanska,
Daniel Borkmann, linux-kselftest, linux-kernel, Haishuang Yan
Now that bareudp allows BIG TCP too, run the same checks over bareudp as
for vxlan and geneve.
bareudp only works in external mode, so attach the tunnel metadata to
all packets sent through the device with a tc tunnel_key action on
egress. The device uses ethertype ipv4 with multiproto, so that both
IPv4 and IPv6 traffic can go through it. Its MTU does not account for
the encapsulation, so lower it to leave room for the IPv6 and UDP
headers, otherwise the encapsulated packets would be fragmented.
Assisted-by: LLM
Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
---
.../testing/selftests/net/big_tcp_tunnels.sh | 55 ++++++++++++++++---
1 file changed, 46 insertions(+), 9 deletions(-)
diff --git a/tools/testing/selftests/net/big_tcp_tunnels.sh b/tools/testing/selftests/net/big_tcp_tunnels.sh
index cc0875e52fb9..b0390b2c9f11 100755
--- a/tools/testing/selftests/net/big_tcp_tunnels.sh
+++ b/tools/testing/selftests/net/big_tcp_tunnels.sh
@@ -1,7 +1,7 @@
#!/usr/bin/env bash
# SPDX-License-Identifier: GPL-2.0
#
-# Testing for IPv4 and IPv6 BIG TCP over VXLAN and GENEVE tunnels.
+# Testing for IPv4 and IPv6 BIG TCP over VXLAN, GENEVE and bareudp tunnels.
source "$(dirname "$0")/lib.sh"
@@ -53,6 +53,24 @@ setup() {
DEFAULT_TCP_MIN_TSO_SEGS=$(ip netns exec "$CLIENT_NS" sysctl -n net.ipv4.tcp_min_tso_segs)
}
+# Create a bareudp device. bareudp only works in external mode: attach the
+# tunnel metadata to all packets sent through the device. Its MTU does not
+# account for the encapsulation either, so leave room for IPv6 and UDP
+# headers.
+# $1: netns, $2: device, $3: local underlay address, $4: remote one
+setup_bareudp() {
+ ip -netns "$1" link add "$2" type bareudp \
+ dstport 6635 ethertype ipv4 multiproto &&
+ ip -netns "$1" link set "$2" mtu 1452 &&
+ tc -netns "$1" qdisc add dev "$2" clsact &&
+ tc -netns "$1" filter add dev "$2" egress matchall \
+ action tunnel_key set src_ip "$3" dst_ip "$4" id 0 ttl 64 &&
+ return 0
+
+ echo "Failed to set up bareudp device $2" >&2
+ return 1
+}
+
setup_tunnel() {
if [ "$2" = 4 ]; then
SERVER_IP="$SERVER_IP4"
@@ -64,26 +82,40 @@ setup_tunnel() {
echo "Setting up ${1^^} over IPv6, veth tx csum offload $3"
fi
- if [ "$1" = vxlan ]; then
+ case "$1" in
+ vxlan)
ip -netns "$CLIENT_NS" link add tun0 type vxlan \
id 5001 remote "$SERVER_IP" local "$CLIENT_IP" dev link0 dstport 4789
- else
+ ;;
+ geneve)
ip -netns "$CLIENT_NS" link add tun0 type geneve \
id 5001 remote "$SERVER_IP"
- fi
+ ;;
+ bareudp)
+ setup_bareudp "$CLIENT_NS" tun0 "$CLIENT_IP" "$SERVER_IP" ||
+ return 1
+ ;;
+ esac
ip -netns "$CLIENT_NS" link set tun0 up
ip -netns "$CLIENT_NS" addr replace "$CLIENT_IP4_TUN/24" dev tun0
ip -netns "$CLIENT_NS" addr replace "$CLIENT_IP6_TUN/112" dev tun0 nodad
ip -netns "$CLIENT_NS" link set tun0 \
gso_max_size 196608 gso_ipv4_max_size 196608 \
gro_max_size 196608 gro_ipv4_max_size 196608
- if [ "$1" = vxlan ]; then
+ case "$1" in
+ vxlan)
ip -netns "$SERVER_NS" link add tun1 type vxlan \
id 5001 remote "$CLIENT_IP" local "$SERVER_IP" dev link1 dstport 4789
- else
+ ;;
+ geneve)
ip -netns "$SERVER_NS" link add tun1 type geneve \
id 5001 remote "$CLIENT_IP"
- fi
+ ;;
+ bareudp)
+ setup_bareudp "$SERVER_NS" tun1 "$SERVER_IP" "$CLIENT_IP" ||
+ return 1
+ ;;
+ esac
ip -netns "$SERVER_NS" link set tun1 up
ip -netns "$SERVER_NS" addr replace "$SERVER_IP4_TUN/24" dev tun1
ip -netns "$SERVER_NS" addr replace "$SERVER_IP6_TUN/112" dev tun1 nodad
@@ -112,7 +144,7 @@ do_test() {
local packets_threshold="$PACKETS_THRESHOLD"
# When tx csum offload is off, software GSO is performed before passing the
- # packet to veth. Check BIG TCP packets inside the VXLAN tunnel to verify
+ # packet to veth. Check BIG TCP packets inside the tunnel to verify
# the software checksum path: if the checksum code is broken, these packets
# will be dropped.
if [ "$3" = on ]; then
@@ -192,6 +224,11 @@ if ! iptables --version &> /dev/null; then
exit "$ksft_skip"
fi
+if ! tc -V &> /dev/null; then
+ echo "SKIP: Could not run test without tc tool"
+ exit "$ksft_skip"
+fi
+
if ! ethtool --version &> /dev/null; then
echo "SKIP: Could not run test without ethtool tool"
exit "$ksft_skip"
@@ -205,7 +242,7 @@ fi
WORKDIR=$(mktemp -d)
trap cleanup EXIT
setup
-for tunnel in vxlan geneve; do
+for tunnel in vxlan geneve bareudp; do
for tun_family in 4 6; do
for traffic_family in 4 6; do
for csum_offload in on off; do
--
2.43.0
^ permalink raw reply related [flat|nested] 5+ messages in thread