[PATCH net-next 0/5] mlxsw: Handle MTU values

[PATCH net-next 0/5] mlxsw: Handle MTU values

[Petr Machata]

Amit Cohen writes:

The driver uses two values for maximum MTU, but neither is accurate.
In addition, the value which is configured to hardware is not calculated
correctly. Handle these issues and expose accurate values for minimum
and maximum MTU per netdevice.

Add test cases to check that the exposed values are really supported.

Patch set overview:
Patches #1-#3 set the driver to use accurate values for MTU
Patch #4 aligns the driver to always use the same value for maximum MTU
Patch #5 adds a test

Amit Cohen (5):
  mlxsw: port: Edit maximum MTU value
  mlxsw: Adjust MTU value to hardware check
  mlxsw: spectrum: Set more accurate values for netdevice min/max MTU
  mlxsw: Use the same maximum MTU value throughout the driver
  selftests: forwarding: Add test for minimum and maximum MTU

 drivers/net/ethernet/mellanox/mlxsw/port.h    |   3 +-
 .../net/ethernet/mellanox/mlxsw/spectrum.c    |  31 +-
 .../net/ethernet/mellanox/mlxsw/spectrum.h    |   1 -
 .../mellanox/mlxsw/spectrum_buffers.c         |   8 +-
 .../testing/selftests/net/forwarding/Makefile |   1 +
 .../selftests/net/forwarding/min_max_mtu.sh   | 283 ++++++++++++++++++
 6 files changed, 295 insertions(+), 32 deletions(-)
 create mode 100755 tools/testing/selftests/net/forwarding/min_max_mtu.sh

-- 
2.45.0

[PATCH net-next 1/5] mlxsw: port: Edit maximum MTU value

[Petr Machata]

From: Amit Cohen <amcohen@nvidia.com>

Currently mlxsw driver supports up to 10000 bytes for maximum MTU, this
value is not accurate, we can support up to 10K bytes. Change the value to
the maximum supported MTU by firmware.

Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
---
 drivers/net/ethernet/mellanox/mlxsw/port.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/port.h b/drivers/net/ethernet/mellanox/mlxsw/port.h
index ac4d4ea51597..aa309615eff3 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/port.h
+++ b/drivers/net/ethernet/mellanox/mlxsw/port.h
@@ -6,7 +6,7 @@
 
 #include <linux/types.h>
 
-#define MLXSW_PORT_MAX_MTU		10000
+#define MLXSW_PORT_MAX_MTU		(10 * 1024)
 
 #define MLXSW_PORT_DEFAULT_VID		1
 
-- 
2.45.0

[PATCH net-next 2/5] mlxsw: Adjust MTU value to hardware check

[Petr Machata]

From: Amit Cohen <amcohen@nvidia.com>

Ethernet frame consists of - Ethernet header, payload, FCS. The MTU value
which is used by user is the size of the payload, which means that when
user sets MTU to X, the total frame size will be larger due to the addition
of the Ethernet header and FCS.

Spectrum ASICs take into account Ethernet header and FCS as part of packet
size for MTU check. Adjust MTU value when user sets MTU, to configure the
MTU size which is required by hardware. The Tx header length which was used
by the driver is not relevant for such calculation, take into account
Ethernet header (with VLAN extension) and FCS.

Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
---
 drivers/net/ethernet/mellanox/mlxsw/port.h     | 1 +
 drivers/net/ethernet/mellanox/mlxsw/spectrum.c | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/port.h b/drivers/net/ethernet/mellanox/mlxsw/port.h
index aa309615eff3..0a73b1a4526e 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/port.h
+++ b/drivers/net/ethernet/mellanox/mlxsw/port.h
@@ -7,6 +7,7 @@
 #include <linux/types.h>
 
 #define MLXSW_PORT_MAX_MTU		(10 * 1024)
+#define MLXSW_PORT_ETH_FRAME_HDR	(ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN)
 
 #define MLXSW_PORT_DEFAULT_VID		1
 
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
index 030ed71f945d..879daa18ccca 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
@@ -425,7 +425,7 @@ static int mlxsw_sp_port_mtu_set(struct mlxsw_sp_port *mlxsw_sp_port, u16 mtu)
 	struct mlxsw_sp *mlxsw_sp = mlxsw_sp_port->mlxsw_sp;
 	char pmtu_pl[MLXSW_REG_PMTU_LEN];
 
-	mtu += MLXSW_TXHDR_LEN + ETH_HLEN;
+	mtu += MLXSW_PORT_ETH_FRAME_HDR;
 	if (mtu > mlxsw_sp_port->max_mtu)
 		return -EINVAL;
 
-- 
2.45.0

[PATCH net-next 3/5] mlxsw: spectrum: Set more accurate values for netdevice min/max MTU

[Petr Machata]

From: Amit Cohen <amcohen@nvidia.com>

Currently, the driver uses ETH_MAX_MTU as maximum MTU of netdevices,
instead, use the accurate value which is supported by the driver.
Subtract Ethernet headers which are taken into account by hardware for
MTU checking, as described in the previous patch.

Set minimum MTU to ETH_MIN_MTU, as zero MTU is not really supported.

With this change:
a. The stack will do the MTU checking, so we can remove it from the driver.
b. User space will be able to query the actual MTU limits.
   Before this patch:
   $ ip -j -d link show dev swp1 | jq | grep mtu
    "mtu": 1500,
    "min_mtu": 0,
    "max_mtu": 65535,

   With this patch:
   $ ip -j -d link show dev swp1 | jq | grep mtu
    "mtu": 1500,
    "min_mtu": 68,
    "max_mtu": 10218,

Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
index 879daa18ccca..c5856f4d6b8b 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
@@ -426,8 +426,6 @@ static int mlxsw_sp_port_mtu_set(struct mlxsw_sp_port *mlxsw_sp_port, u16 mtu)
 	char pmtu_pl[MLXSW_REG_PMTU_LEN];
 
 	mtu += MLXSW_PORT_ETH_FRAME_HDR;
-	if (mtu > mlxsw_sp_port->max_mtu)
-		return -EINVAL;
 
 	mlxsw_reg_pmtu_pack(pmtu_pl, mlxsw_sp_port->local_port, mtu);
 	return mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(pmtu), pmtu_pl);
@@ -1697,8 +1695,8 @@ static int mlxsw_sp_port_create(struct mlxsw_sp *mlxsw_sp, u16 local_port,
 			 NETIF_F_HW_VLAN_CTAG_FILTER | NETIF_F_HW_TC;
 	dev->hw_features |= NETIF_F_HW_TC | NETIF_F_LOOPBACK;
 
-	dev->min_mtu = 0;
-	dev->max_mtu = ETH_MAX_MTU;
+	dev->min_mtu = ETH_MIN_MTU;
+	dev->max_mtu = MLXSW_PORT_MAX_MTU - MLXSW_PORT_ETH_FRAME_HDR;
 
 	/* Each packet needs to have a Tx header (metadata) on top all other
 	 * headers.
-- 
2.45.0

[PATCH net-next 4/5] mlxsw: Use the same maximum MTU value throughout the driver

[Petr Machata]

From: Amit Cohen <amcohen@nvidia.com>

Currently, the driver uses two different values for maximum MTU, one is
stored in mlxsw_port->dev->max_mtu and the second is stored in
mlxsw_port->max_mtu. The second one is set to value which is queried from
firmware. This value was never tested, and unfortunately is not really
supported. That means that with the existing code, user can set MTU to
X, which is not really supported by firmware and which is bigger than
buffer size which is allocated in pci.

To make the driver consistent, use only mlxsw_port->dev->max_mtu for
maximum MTU value, for buffers headroom add Ethernet frame headers, which
are not included in mlxsw_port->dev->max_mtu. Remove mlxsw_port->max_mtu.

Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
---
 .../net/ethernet/mellanox/mlxsw/spectrum.c    | 23 -------------------
 .../net/ethernet/mellanox/mlxsw/spectrum.h    |  1 -
 .../mellanox/mlxsw/spectrum_buffers.c         |  8 +++++--
 3 files changed, 6 insertions(+), 26 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
index c5856f4d6b8b..f064789f3240 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
@@ -405,21 +405,6 @@ static int mlxsw_sp_port_dev_addr_init(struct mlxsw_sp_port *mlxsw_sp_port)
 					  mlxsw_sp_port->dev->dev_addr);
 }
 
-static int mlxsw_sp_port_max_mtu_get(struct mlxsw_sp_port *mlxsw_sp_port, int *p_max_mtu)
-{
-	struct mlxsw_sp *mlxsw_sp = mlxsw_sp_port->mlxsw_sp;
-	char pmtu_pl[MLXSW_REG_PMTU_LEN];
-	int err;
-
-	mlxsw_reg_pmtu_pack(pmtu_pl, mlxsw_sp_port->local_port, 0);
-	err = mlxsw_reg_query(mlxsw_sp->core, MLXSW_REG(pmtu), pmtu_pl);
-	if (err)
-		return err;
-
-	*p_max_mtu = mlxsw_reg_pmtu_max_mtu_get(pmtu_pl);
-	return 0;
-}
-
 static int mlxsw_sp_port_mtu_set(struct mlxsw_sp_port *mlxsw_sp_port, u16 mtu)
 {
 	struct mlxsw_sp *mlxsw_sp = mlxsw_sp_port->mlxsw_sp;
@@ -1725,13 +1710,6 @@ static int mlxsw_sp_port_create(struct mlxsw_sp *mlxsw_sp, u16 local_port,
 		goto err_max_speed_get;
 	}
 
-	err = mlxsw_sp_port_max_mtu_get(mlxsw_sp_port, &mlxsw_sp_port->max_mtu);
-	if (err) {
-		dev_err(mlxsw_sp->bus_info->dev, "Port %d: Failed to get maximum MTU\n",
-			mlxsw_sp_port->local_port);
-		goto err_port_max_mtu_get;
-	}
-
 	err = mlxsw_sp_port_mtu_set(mlxsw_sp_port, ETH_DATA_LEN);
 	if (err) {
 		dev_err(mlxsw_sp->bus_info->dev, "Port %d: Failed to set MTU\n",
@@ -1875,7 +1853,6 @@ static int mlxsw_sp_port_create(struct mlxsw_sp *mlxsw_sp, u16 local_port,
 err_port_buffers_init:
 err_port_admin_status_set:
 err_port_mtu_set:
-err_port_max_mtu_get:
 err_max_speed_get:
 err_port_speed_by_width_set:
 err_port_system_port_mapping_set:
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.h b/drivers/net/ethernet/mellanox/mlxsw/spectrum.h
index 3beb5d0847ab..bb0586b45c8d 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.h
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.h
@@ -359,7 +359,6 @@ struct mlxsw_sp_port {
 		u16 egr_types;
 		struct mlxsw_sp_ptp_port_stats stats;
 	} ptp;
-	int max_mtu;
 	u32 max_speed;
 	struct mlxsw_sp_hdroom *hdroom;
 	u64 module_overheat_initial_val;
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_buffers.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_buffers.c
index ba090262e27e..2c0cfa79d138 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_buffers.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_buffers.c
@@ -399,11 +399,13 @@ void mlxsw_sp_hdroom_bufs_reset_sizes(struct mlxsw_sp_port *mlxsw_sp_port,
 				      struct mlxsw_sp_hdroom *hdroom)
 {
 	struct mlxsw_sp *mlxsw_sp = mlxsw_sp_port->mlxsw_sp;
+	unsigned int max_mtu = mlxsw_sp_port->dev->max_mtu;
 	u16 reserve_cells;
 	int i;
 
+	max_mtu += MLXSW_PORT_ETH_FRAME_HDR;
 	/* Internal buffer. */
-	reserve_cells = mlxsw_sp_hdroom_int_buf_size_get(mlxsw_sp, mlxsw_sp_port->max_mtu,
+	reserve_cells = mlxsw_sp_hdroom_int_buf_size_get(mlxsw_sp, max_mtu,
 							 mlxsw_sp_port->max_speed);
 	reserve_cells = mlxsw_sp_port_headroom_8x_adjust(mlxsw_sp_port, reserve_cells);
 	hdroom->int_buf.reserve_cells = reserve_cells;
@@ -613,7 +615,9 @@ static int mlxsw_sp_port_headroom_init(struct mlxsw_sp_port *mlxsw_sp_port)
 	mlxsw_sp_hdroom_bufs_reset_sizes(mlxsw_sp_port, &hdroom);
 
 	/* Buffer 9 is used for control traffic. */
-	size9 = mlxsw_sp_port_headroom_8x_adjust(mlxsw_sp_port, mlxsw_sp_port->max_mtu);
+	size9 = mlxsw_sp_port_headroom_8x_adjust(mlxsw_sp_port,
+						 mlxsw_sp_port->dev->max_mtu +
+						 MLXSW_PORT_ETH_FRAME_HDR);
 	hdroom.bufs.buf[9].size_cells = mlxsw_sp_bytes_cells(mlxsw_sp, size9);
 
 	return __mlxsw_sp_hdroom_configure(mlxsw_sp_port, &hdroom, true);
-- 
2.45.0

[PATCH net-next 5/5] selftests: forwarding: Add test for minimum and maximum MTU

[Petr Machata]

From: Amit Cohen <amcohen@nvidia.com>

Add cases to check minimum and maximum MTU which are exposed via
"ip -d link show". Test configuration and traffic. Use VLAN devices as
usually VLAN header (4 bytes) is not included in the MTU, and drivers
should configure hardware correctly to send maximum MTU payload size
in VLAN tagged packets.

$ ./min_max_mtu.sh
TEST: ping						[ OK ]
TEST: ping6						[ OK ]
TEST: Test maximum MTU configuration			[ OK ]
TEST: Test traffic, packet size is maximum MTU		[ OK ]
TEST: Test minimum MTU configuration			[ OK ]
TEST: Test traffic, packet size is minimum MTU		[ OK ]

Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
---

Cc: Shuah Khan <shuah@kernel.org>
Cc: linux-kselftest@vger.kernel.org

 .../testing/selftests/net/forwarding/Makefile |   1 +
 .../selftests/net/forwarding/min_max_mtu.sh   | 283 ++++++++++++++++++
 2 files changed, 284 insertions(+)
 create mode 100755 tools/testing/selftests/net/forwarding/min_max_mtu.sh

diff --git a/tools/testing/selftests/net/forwarding/Makefile b/tools/testing/selftests/net/forwarding/Makefile
index 99576d7ecbf6..224346426ef2 100644
--- a/tools/testing/selftests/net/forwarding/Makefile
+++ b/tools/testing/selftests/net/forwarding/Makefile
@@ -39,6 +39,7 @@ TEST_PROGS = bridge_fdb_learning_limit.sh \
 	ipip_hier_gre.sh \
 	lib_sh_test.sh \
 	local_termination.sh \
+	min_max_mtu.sh \
 	mirror_gre_bound.sh \
 	mirror_gre_bridge_1d.sh \
 	mirror_gre_bridge_1d_vlan.sh \
diff --git a/tools/testing/selftests/net/forwarding/min_max_mtu.sh b/tools/testing/selftests/net/forwarding/min_max_mtu.sh
new file mode 100755
index 000000000000..97bb8b221bed
--- /dev/null
+++ b/tools/testing/selftests/net/forwarding/min_max_mtu.sh
@@ -0,0 +1,283 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+# +--------------------+
+# | H1                 |
+# |                    |
+# |           $h1.10 + |
+# |     192.0.2.2/24 | |
+# | 2001:db8:1::2/64 | |
+# |                  | |
+# |              $h1 + |
+# |                  | |
+# +------------------|-+
+#                    |
+# +------------------|-+
+# | SW               | |
+# |            $swp1 + |
+# |                  | |
+# |         $swp1.10 + |
+# |     192.0.2.1/24   |
+# | 2001:db8:1::1/64   |
+# |                    |
+# +--------------------+
+
+ALL_TESTS="
+	ping_ipv4
+	ping_ipv6
+	max_mtu_config_test
+	max_mtu_traffic_test
+	min_mtu_config_test
+	min_mtu_traffic_test
+"
+
+NUM_NETIFS=2
+source lib.sh
+
+h1_create()
+{
+	simple_if_init $h1
+	vlan_create $h1 10 v$h1 192.0.2.2/24 2001:db8:1::2/64
+}
+
+h1_destroy()
+{
+	vlan_destroy $h1 10 192.0.2.2/24 2001:db8:1::2/64
+	simple_if_fini $h1
+}
+
+switch_create()
+{
+	ip li set dev $swp1 up
+	vlan_create $swp1 10 "" 192.0.2.1/24 2001:db8:1::1/64
+}
+
+switch_destroy()
+{
+	ip li set dev $swp1 down
+	vlan_destroy $swp1 10
+}
+
+setup_prepare()
+{
+	h1=${NETIFS[p1]}
+	swp1=${NETIFS[p2]}
+
+	vrf_prepare
+
+	h1_create
+
+	switch_create
+
+	forwarding_enable
+}
+
+cleanup()
+{
+	pre_cleanup
+
+	forwarding_restore
+
+	switch_destroy
+
+	h1_destroy
+
+	vrf_cleanup
+}
+
+ping_ipv4()
+{
+	ping_test $h1.10 192.0.2.1
+}
+
+ping_ipv6()
+{
+	ping6_test $h1.10 2001:db8:1::1
+}
+
+min_max_mtu_get_if()
+{
+	local dev=$1; shift
+	local min_max=$1; shift
+
+	ip -d -j link show $dev | jq ".[].$min_max"
+}
+
+ensure_compatible_min_max_mtu()
+{
+	local min_max=$1; shift
+
+	local mtu=$(min_max_mtu_get_if ${NETIFS[p1]} $min_max)
+	local i
+
+	for ((i = 2; i <= NUM_NETIFS; ++i)); do
+		local current_mtu=$(min_max_mtu_get_if ${NETIFS[p$i]} $min_max)
+
+		if [ $current_mtu -ne $mtu ]; then
+			return 1
+		fi
+	done
+}
+
+mtu_set_if()
+{
+	local dev=$1; shift
+	local mtu=$1; shift
+	local should_fail=${1:-0}; shift
+
+	mtu_set $dev $mtu 2>/dev/null
+	check_err_fail $should_fail $? "Set MTU $mtu for $dev"
+}
+
+mtu_set_all_if()
+{
+	local mtu=$1; shift
+	local i
+
+	for ((i = 1; i <= NUM_NETIFS; ++i)); do
+		mtu_set_if ${NETIFS[p$i]} $mtu
+		mtu_set_if ${NETIFS[p$i]}.10 $mtu
+	done
+}
+
+mtu_restore_all_if()
+{
+	local i
+
+	for ((i = 1; i <= NUM_NETIFS; ++i)); do
+		mtu_restore ${NETIFS[p$i]}.10
+		mtu_restore ${NETIFS[p$i]}
+	done
+}
+
+mtu_test_ping4()
+{
+	local mtu=$1; shift
+	local should_fail=$1; shift
+
+	# Ping adds 8 bytes for ICMP header and 20 bytes for IP header
+	local ping_headers_len=$((20 + 8))
+	local pkt_size=$((mtu - ping_headers_len))
+
+	ping_do $h1.10 192.0.2.1 "-s $pkt_size -M do"
+	check_err_fail $should_fail $? "Ping, packet size: $pkt_size"
+}
+
+mtu_test_ping6()
+{
+	local mtu=$1; shift
+	local should_fail=$1; shift
+
+	# Ping adds 8 bytes for ICMP header and 40 bytes for IPv6 header
+	local ping6_headers_len=$((40 + 8))
+	local pkt_size=$((mtu - ping6_headers_len))
+
+	ping6_do $h1.10 2001:db8:1::1 "-s $pkt_size -M do"
+	check_err_fail $should_fail $? "Ping6, packet size: $pkt_size"
+}
+
+max_mtu_config_test()
+{
+	local i
+
+	RET=0
+
+	for ((i = 1; i <= NUM_NETIFS; ++i)); do
+		local dev=${NETIFS[p$i]}
+		local max_mtu=$(min_max_mtu_get_if $dev "max_mtu")
+		local should_fail
+
+		should_fail=0
+		mtu_set_if $dev $max_mtu $should_fail
+		mtu_restore $dev
+
+		should_fail=1
+		mtu_set_if $dev $((max_mtu + 1)) $should_fail
+		mtu_restore $dev
+	done
+
+	log_test "Test maximum MTU configuration"
+}
+
+max_mtu_traffic_test()
+{
+	local should_fail
+	local max_mtu
+
+	RET=0
+
+	if ! ensure_compatible_min_max_mtu "max_mtu"; then
+		log_test_xfail "Topology has incompatible maximum MTU values"
+		return
+	fi
+
+	max_mtu=$(min_max_mtu_get_if ${NETIFS[p1]} "max_mtu")
+
+	should_fail=0
+	mtu_set_all_if $max_mtu
+	mtu_test_ping4 $max_mtu $should_fail
+	mtu_test_ping6 $max_mtu $should_fail
+	mtu_restore_all_if
+
+	should_fail=1
+	mtu_set_all_if $((max_mtu - 1))
+	mtu_test_ping4 $max_mtu $should_fail
+	mtu_test_ping6 $max_mtu $should_fail
+	mtu_restore_all_if
+
+	log_test "Test traffic, packet size is maximum MTU"
+}
+
+min_mtu_config_test()
+{
+	local i
+
+	RET=0
+
+	for ((i = 1; i <= NUM_NETIFS; ++i)); do
+		local dev=${NETIFS[p$i]}
+		local min_mtu=$(min_max_mtu_get_if $dev "min_mtu")
+		local should_fail
+
+		should_fail=0
+		mtu_set_if $dev $min_mtu $should_fail
+		mtu_restore $dev
+
+		should_fail=1
+		mtu_set_if $dev $((min_mtu - 1)) $should_fail
+		mtu_restore $dev
+	done
+
+	log_test "Test minimum MTU configuration"
+}
+
+min_mtu_traffic_test()
+{
+	local should_fail=0
+	local min_mtu
+
+	RET=0
+
+	if ! ensure_compatible_min_max_mtu "min_mtu"; then
+		log_test_xfail "Topology has incompatible minimum MTU values"
+		return
+	fi
+
+	min_mtu=$(min_max_mtu_get_if ${NETIFS[p1]} "min_mtu")
+	mtu_set_all_if $min_mtu
+	mtu_test_ping4 $min_mtu $should_fail
+	# Do not test minimum MTU with IPv6, as IPv6 requires higher MTU.
+
+	mtu_restore_all_if
+
+	log_test "Test traffic, packet size is minimum MTU"
+}
+
+trap cleanup EXIT
+
+setup_prepare
+setup_wait
+
+tests_run
+
+exit $EXIT_STATUS
-- 
2.45.0

Re: [PATCH net-next 0/5] mlxsw: Handle MTU values

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Thu, 13 Jun 2024 16:07:53 +0200 you wrote:
> Amit Cohen writes:
> 
> The driver uses two values for maximum MTU, but neither is accurate.
> In addition, the value which is configured to hardware is not calculated
> correctly. Handle these issues and expose accurate values for minimum
> and maximum MTU per netdevice.
> 
> [...]

Here is the summary with links:
  - [net-next,1/5] mlxsw: port: Edit maximum MTU value
    https://git.kernel.org/netdev/net-next/c/cae7fd47dfe1
  - [net-next,2/5] mlxsw: Adjust MTU value to hardware check
    https://git.kernel.org/netdev/net-next/c/d361536fc2df
  - [net-next,3/5] mlxsw: spectrum: Set more accurate values for netdevice min/max MTU
    https://git.kernel.org/netdev/net-next/c/753aacfc032d
  - [net-next,4/5] mlxsw: Use the same maximum MTU value throughout the driver
    https://git.kernel.org/netdev/net-next/c/3e7856545d36
  - [net-next,5/5] selftests: forwarding: Add test for minimum and maximum MTU
    https://git.kernel.org/netdev/net-next/c/4be3dcc9bf04

You are awesome, thank you!
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