[PATCH net] selftests: net: validate team flags propagation - Linux-kselftest-mirror

15 May 2025

Cover three recent cases:
1. missing ops locking for the lowers during netdev_sync_lower_features
2. missing locking for dev_set_promiscuity (plus netdev_ops_assert_locked
   with a comment on why/when it's needed)
3. rcu lock during team_change_rx_flags
Verified that each one triggers when the respective fix is reverted.
Not sure about the placement, but since it all relies on teaming,
added to the teaming directory.
One ugly bit is that I add NETIF_F_LRO to netdevsim; there is no way
to trigger netdev_sync_lower_features without it.
Signed-off-by: Stanislav Fomichev stfomichev@gmail.com
---
 drivers/net/netdevsim/netdev.c                |  2 +
 net/core/dev.c                                | 10 ++-
 .../selftests/drivers/net/team/Makefile       |  2 +-
 .../testing/selftests/drivers/net/team/config |  1 +
 .../selftests/drivers/net/team/propagation.sh | 79 +++++++++++++++++++
 5 files changed, 92 insertions(+), 2 deletions(-)
 create mode 100755 tools/testing/selftests/drivers/net/team/propagation.sh

diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c
index 0e0321a7ddd7..3bd1f8cffee8 100644
--- a/drivers/net/netdevsim/netdev.c
+++ b/drivers/net/netdevsim/netdev.c
@@ -879,11 +879,13 @@ static void nsim_setup(struct net_device *dev)
    		 NETIF_F_SG |
    		 NETIF_F_FRAGLIST |
    		 NETIF_F_HW_CSUM |
+			 NETIF_F_LRO |
    		 NETIF_F_TSO;
    dev->hw_features |= NETIF_F_HW_TC |
    		    NETIF_F_SG |
    		    NETIF_F_FRAGLIST |
    		    NETIF_F_HW_CSUM |
+			    NETIF_F_LRO |
    		    NETIF_F_TSO;
    dev->max_mtu = ETH_MAX_MTU;
    dev->xdp_features = NETDEV_XDP_ACT_HW_OFFLOAD;
diff --git a/net/core/dev.c b/net/core/dev.c
index 0d891634c692..4debd4b8e0f5 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -9188,8 +9188,16 @@ static int __dev_set_promiscuity(struct net_device *dev, int inc, bool notify)
dev_change_rx_flags(dev, IFF_PROMISC);
    }
-	if (notify)
+	if (notify) {
+		/* The ops lock is only required to ensure consistent locking
+		 * for `NETDEV_CHANGE` notifiers. This function is sometimes
+		 * called without the lock, even for devices that are ops
+		 * locked, such as in `dev_uc_sync_multiple` when using
+		 * bonding or teaming.
+		 */
+		netdev_ops_assert_locked(dev);
    	__dev_notify_flags(dev, old_flags, IFF_PROMISC, 0, NULL);
+	}
    return 0;
 }
diff --git a/tools/testing/selftests/drivers/net/team/Makefile b/tools/testing/selftests/drivers/net/team/Makefile
index 2d5a76d99181..eaf6938f100e 100644
--- a/tools/testing/selftests/drivers/net/team/Makefile
+++ b/tools/testing/selftests/drivers/net/team/Makefile
@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 # Makefile for net selftests
-TEST_PROGS := dev_addr_lists.sh
+TEST_PROGS := dev_addr_lists.sh propagation.sh
TEST_INCLUDES := \
    ../bonding/lag_lib.sh \
diff --git a/tools/testing/selftests/drivers/net/team/config b/tools/testing/selftests/drivers/net/team/config
index b5e3a3aad4bf..636b3525b679 100644
--- a/tools/testing/selftests/drivers/net/team/config
+++ b/tools/testing/selftests/drivers/net/team/config
@@ -1,5 +1,6 @@
 CONFIG_DUMMY=y
 CONFIG_IPV6=y
 CONFIG_MACVLAN=y
+CONFIG_NETDEVSIM=m
 CONFIG_NET_TEAM=y
 CONFIG_NET_TEAM_MODE_LOADBALANCE=y
diff --git a/tools/testing/selftests/drivers/net/team/propagation.sh b/tools/testing/selftests/drivers/net/team/propagation.sh
new file mode 100755
index 000000000000..849a5f2cb3a7
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/team/propagation.sh
@@ -0,0 +1,79 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+set -e
+
+NSIM_LRO_ID=$((256 + RANDOM % 256))
+NSIM_LRO_SYS=/sys/bus/netdevsim/devices/netdevsim$NSIM_LRO_ID
+
+NSIM_DEV_SYS_NEW=/sys/bus/netdevsim/new_device
+NSIM_DEV_SYS_DEL=/sys/bus/netdevsim/del_device
+
+cleanup()
+{
+	ip link del dummyteam &>/dev/null
+	ip link del team0 &>/dev/null
+	echo $NSIM_LRO_ID > $NSIM_DEV_SYS_DEL
+}
+
+# Trigger LRO propagation to the lower.
+# https://lore.kernel.org/netdev/aBvOpkIoxcr9PfDg@mini-arch/
+team_lro()
+{
+	# using netdevsim because it supports NETIF_F_LRO
+	NSIM_LRO_NAME=$(find $NSIM_LRO_SYS/net -maxdepth 1 -type d ! \
+		-path $NSIM_LRO_SYS/net -exec basename {} ;)
+
+	ip link add name team0 type team
+	ip link set $NSIM_LRO_NAME down
+	ip link set dev $NSIM_LRO_NAME master team0
+	ip link set team0 up
+	ethtool -K team0 large-receive-offload off
+
+	ip link del team0
+}
+
+# Trigger promisc propagation to the lower during IFLA_MASTER.
+# https://lore.kernel.org/netdev/20250506032328.3003050-1-sdf@fomichev.me/
+team_promisc()
+{
+	ip link add name dummyteam type dummy
+	ip link add name team0 type team
+	ip link set dummyteam down
+	ip link set team0 promisc on
+	ip link set dev dummyteam master team0
+	ip link set team0 up
+
+	ip link del team0
+	ip link del dummyteam
+}
+
+# Trigger promisc propagation to the lower via netif_change_flags (aka
+# ndo_change_rx_flags).
+# https://lore.kernel.org/netdev/20250514220319.3505158-1-stfomichev@gmail.com...
+team_change_flags()
+{
+	ip link add name dummyteam type dummy
+	ip link add name team0 type team
+	ip link set dummyteam down
+	ip link set dev dummyteam master team0
+	ip link set team0 up
+	ip link set team0 promisc on
+
+	# Make sure we can add more L2 addresses without any issues.
+	ip link add link team0 address 00:00:00:00:00:01 team0.1 type macvlan
+	ip link set team0.1 up
+
+	ip link del team0.1
+	ip link del team0
+	ip link del dummyteam
+}
+
+trap cleanup EXIT
+modprobe netdevsim || :
+echo $NSIM_LRO_ID > $NSIM_DEV_SYS_NEW
+udevadm settle
+team_lro
+team_promisc
+team_change_flags
+modprobe -r netdevsim || :
-- 
2.49.0



    