[PATCH net v5 0/4] net: netpoll: fix memory leak and add comprehensive selftests

[PATCH net v5 0/4] net: netpoll: fix memory leak and add comprehensive selftests

[Breno Leitao]

Fix a memory leak in netpoll and introduce netconsole selftests that
expose the issue when running with kmemleak detection enabled.

This patchset includes a selftest for netpoll with multiple concurrent
users (netconsole + bonding), which simulates the scenario from test[1]
that originally demonstrated the issue allegedly fixed by commit
efa95b01da18 ("netpoll: fix use after free") - a commit that is now
being reverted.

Sending this to "net" branch because this is a fix, and the selftest
might help with the backports validation.

Link: https://lore.kernel.org/lkml/96b940137a50e5c387687bb4f57de8b0435a653f.1404857349.git.decot@googlers.com/ [1]

Signed-off-by: Breno Leitao <leitao@debian.org>
---
Changes in v5:
- Set CONFIG_BONDING=m in selftests/drivers/net/config.
- Link to v4: https://lore.kernel.org/r/20250917-netconsole_torture-v4-0-0a5b3b8f81ce@debian.org

Changes in v4:
- Added an additional selftest to test multiple netpoll users in
  parallel
- Link to v3: https://lore.kernel.org/r/20250905-netconsole_torture-v3-0-875c7febd316@debian.org

Changes in v3:
- This patchset is a merge of the fix and the selftest together as
  recommended by Jakub.

Changes in v2:
- Reuse the netconsole creation from lib_netcons.sh. Thus, refactoring
  the create_dynamic_target() (Jakub)
- Move the "wait" to after all the messages has been sent.
- Link to v1: https://lore.kernel.org/r/20250902-netconsole_torture-v1-1-03c6066598e9@debian.org

---
Breno Leitao (4):
      net: netpoll: fix incorrect refcount handling causing incorrect cleanup
      selftest: netcons: refactor target creation
      selftest: netcons: create a torture test
      selftest: netcons: add test for netconsole over bonded interfaces

 net/core/netpoll.c                                 |   7 +-
 tools/testing/selftests/drivers/net/Makefile       |   2 +
 tools/testing/selftests/drivers/net/config         |   1 +
 .../selftests/drivers/net/lib/sh/lib_netcons.sh    | 197 ++++++++++++++++++---
 .../selftests/drivers/net/netcons_over_bonding.sh  |  76 ++++++++
 .../selftests/drivers/net/netcons_torture.sh       | 127 +++++++++++++
 6 files changed, 385 insertions(+), 25 deletions(-)
---
base-commit: 5e87fdc37f8dc619549d49ba5c951b369ce7c136
change-id: 20250902-netconsole_torture-8fc23f0aca99

Best regards,
--  
Breno Leitao <leitao@debian.org>

[PATCH net v5 1/4] net: netpoll: fix incorrect refcount handling causing incorrect cleanup

[Breno Leitao]

commit efa95b01da18 ("netpoll: fix use after free") incorrectly
ignored the refcount and prematurely set dev->npinfo to NULL during
netpoll cleanup, leading to improper behavior and memory leaks.

Scenario causing lack of proper cleanup:

1) A netpoll is associated with a NIC (e.g., eth0) and netdev->npinfo is
   allocated, and refcnt = 1
   - Keep in mind that npinfo is shared among all netpoll instances. In
     this case, there is just one.

2) Another netpoll is also associated with the same NIC and
   npinfo->refcnt += 1.
   - Now dev->npinfo->refcnt = 2;
   - There is just one npinfo associated to the netdev.

3) When the first netpolls goes to clean up:
   - The first cleanup succeeds and clears np->dev->npinfo, ignoring
     refcnt.
     - It basically calls `RCU_INIT_POINTER(np->dev->npinfo, NULL);`
   - Set dev->npinfo = NULL, without proper cleanup
   - No ->ndo_netpoll_cleanup() is either called

4) Now the second target tries to clean up
   - The second cleanup fails because np->dev->npinfo is already NULL.
     * In this case, ops->ndo_netpoll_cleanup() was never called, and
       the skb pool is not cleaned as well (for the second netpoll
       instance)
  - This leaks npinfo and skbpool skbs, which is clearly reported by
    kmemleak.

Revert commit efa95b01da18 ("netpoll: fix use after free") and adds
clarifying comments emphasizing that npinfo cleanup should only happen
once the refcount reaches zero, ensuring stable and correct netpoll
behavior.

Cc: <stable@vger.kernel.org> # 3.17.x
Cc: Jay Vosburgh <jv@jvosburgh.net>
Fixes: efa95b01da18 ("netpoll: fix use after free")
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Simon Horman <horms@kernel.org>
---
 net/core/netpoll.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 5f65b62346d4e..19676cd379640 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -815,6 +815,10 @@ static void __netpoll_cleanup(struct netpoll *np)
 	if (!npinfo)
 		return;
 
+	/* At this point, there is a single npinfo instance per netdevice, and
+	 * its refcnt tracks how many netpoll structures are linked to it. We
+	 * only perform npinfo cleanup when the refcnt decrements to zero.
+	 */
 	if (refcount_dec_and_test(&npinfo->refcnt)) {
 		const struct net_device_ops *ops;
 
@@ -824,8 +828,7 @@ static void __netpoll_cleanup(struct netpoll *np)
 
 		RCU_INIT_POINTER(np->dev->npinfo, NULL);
 		call_rcu(&npinfo->rcu, rcu_cleanup_netpoll_info);
-	} else
-		RCU_INIT_POINTER(np->dev->npinfo, NULL);
+	}
 
 	skb_pool_flush(np);
 }

-- 
2.47.3

[PATCH net v5 2/4] selftest: netcons: refactor target creation

[Breno Leitao]

Extract the netconsole target creation from create_dynamic_target(), by
moving it from create_dynamic_target() into a new helper function. This
enables other tests to use the creation of netconsole targets with
arbitrary parameters and no sleep.

The new helper will be utilized by forthcoming torture-type selftests
that require dynamic target management.

Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Simon Horman <horms@kernel.org>
---
 .../selftests/drivers/net/lib/sh/lib_netcons.sh    | 30 ++++++++++++++--------
 1 file changed, 19 insertions(+), 11 deletions(-)

diff --git a/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh b/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
index 8e1085e896472..9b5ef8074440c 100644
--- a/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
+++ b/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
@@ -113,31 +113,39 @@ function set_network() {
 	configure_ip
 }
 
-function create_dynamic_target() {
-	local FORMAT=${1:-"extended"}
+function _create_dynamic_target() {
+	local FORMAT="${1:?FORMAT parameter required}"
+	local NCPATH="${2:?NCPATH parameter required}"
 
 	DSTMAC=$(ip netns exec "${NAMESPACE}" \
 		 ip link show "${DSTIF}" | awk '/ether/ {print $2}')
 
 	# Create a dynamic target
-	mkdir "${NETCONS_PATH}"
+	mkdir "${NCPATH}"
 
-	echo "${DSTIP}" > "${NETCONS_PATH}"/remote_ip
-	echo "${SRCIP}" > "${NETCONS_PATH}"/local_ip
-	echo "${DSTMAC}" > "${NETCONS_PATH}"/remote_mac
-	echo "${SRCIF}" > "${NETCONS_PATH}"/dev_name
+	echo "${DSTIP}" > "${NCPATH}"/remote_ip
+	echo "${SRCIP}" > "${NCPATH}"/local_ip
+	echo "${DSTMAC}" > "${NCPATH}"/remote_mac
+	echo "${SRCIF}" > "${NCPATH}"/dev_name
 
 	if [ "${FORMAT}" == "basic" ]
 	then
 		# Basic target does not support release
-		echo 0 > "${NETCONS_PATH}"/release
-		echo 0 > "${NETCONS_PATH}"/extended
+		echo 0 > "${NCPATH}"/release
+		echo 0 > "${NCPATH}"/extended
 	elif [ "${FORMAT}" == "extended" ]
 	then
-		echo 1 > "${NETCONS_PATH}"/extended
+		echo 1 > "${NCPATH}"/extended
 	fi
 
-	echo 1 > "${NETCONS_PATH}"/enabled
+	echo 1 > "${NCPATH}"/enabled
+
+}
+
+function create_dynamic_target() {
+	local FORMAT=${1:-"extended"}
+	local NCPATH=${2:-"$NETCONS_PATH"}
+	_create_dynamic_target "${FORMAT}" "${NCPATH}"
 
 	# This will make sure that the kernel was able to
 	# load the netconsole driver configuration. The console message

-- 
2.47.3

[PATCH net v5 3/4] selftest: netcons: create a torture test

[Breno Leitao]

Create a netconsole test that puts a lot of pressure on the netconsole
list manipulation. Do it by creating dynamic targets and deleting
targets while messages are being sent. Also put interface down while the
messages are being sent, as creating parallel targets.

The code launches three background jobs on distinct schedules:

 * Toggle netcons target every 30 iterations
 * create and delete random_target every 50 iterations
 * toggle iface every 70 iterations

This creates multiple concurrency sources that interact with netconsole
states. This is good practice to simulate stress, and exercise netpoll
and netconsole locks.

This test already found an issue as reported in [1]

Link: https://lore.kernel.org/all/20250901-netpoll_memleak-v1-1-34a181977dfc@debian.org/ [1]
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Andre Carvalho <asantostc@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
---
 tools/testing/selftests/drivers/net/Makefile       |   1 +
 .../selftests/drivers/net/netcons_torture.sh       | 127 +++++++++++++++++++++
 2 files changed, 128 insertions(+)

diff --git a/tools/testing/selftests/drivers/net/Makefile b/tools/testing/selftests/drivers/net/Makefile
index 984ece05f7f92..2b253b1ff4f38 100644
--- a/tools/testing/selftests/drivers/net/Makefile
+++ b/tools/testing/selftests/drivers/net/Makefile
@@ -17,6 +17,7 @@ TEST_PROGS := \
 	netcons_fragmented_msg.sh \
 	netcons_overflow.sh \
 	netcons_sysdata.sh \
+	netcons_torture.sh \
 	netpoll_basic.py \
 	ping.py \
 	queues.py \
diff --git a/tools/testing/selftests/drivers/net/netcons_torture.sh b/tools/testing/selftests/drivers/net/netcons_torture.sh
new file mode 100755
index 0000000000000..723aa2488c19a
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/netcons_torture.sh
@@ -0,0 +1,127 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: GPL-2.0
+
+# Repeatedly send kernel messages, toggles netconsole targets on and off,
+# creates and deletes targets in parallel, and toggles the source interface to
+# simulate stress conditions.
+#
+# This test aims to verify the robustness of netconsole under dynamic
+# configurations and concurrent operations.
+#
+# The major goal is to run this test with LOCKDEP, Kmemleak and KASAN to make
+# sure no issues is reported.
+#
+# Author: Breno Leitao <leitao@debian.org>
+
+set -euo pipefail
+
+SCRIPTDIR=$(dirname "$(readlink -e "${BASH_SOURCE[0]}")")
+
+source "${SCRIPTDIR}"/lib/sh/lib_netcons.sh
+
+# Number of times the main loop run
+ITERATIONS=${1:-1000}
+
+# Only test extended format
+FORMAT="extended"
+# And ipv6 only
+IP_VERSION="ipv6"
+
+# Create, enable and delete some targets.
+create_and_delete_random_target() {
+	COUNT=2
+	RND_PREFIX=$(mktemp -u netcons_rnd_XXXX_)
+
+	if [ -d "${NETCONS_CONFIGFS}/${RND_PREFIX}${COUNT}"  ] || \
+	   [ -d "${NETCONS_CONFIGFS}/${RND_PREFIX}0" ]; then
+		echo "Function didn't finish yet, skipping it." >&2
+		return
+	fi
+
+	# enable COUNT targets
+	for i in $(seq ${COUNT})
+	do
+		RND_TARGET="${RND_PREFIX}"${i}
+		RND_TARGET_PATH="${NETCONS_CONFIGFS}"/"${RND_TARGET}"
+
+		# Basic population so the target can come up
+		_create_dynamic_target "${FORMAT}" "${RND_TARGET_PATH}"
+	done
+
+	echo "netconsole selftest: ${COUNT} additional targets were created" > /dev/kmsg
+	# disable them all
+	for i in $(seq ${COUNT})
+	do
+		RND_TARGET="${RND_PREFIX}"${i}
+		RND_TARGET_PATH="${NETCONS_CONFIGFS}"/"${RND_TARGET}"
+		echo 0 > "${RND_TARGET_PATH}"/enabled
+		rmdir "${RND_TARGET_PATH}"
+	done
+}
+
+# Disable and enable the target mid-air, while messages
+# are being transmitted.
+toggle_netcons_target() {
+	for i in $(seq 2)
+	do
+		if [ ! -d "${NETCONS_PATH}" ]
+		then
+			break
+		fi
+		echo 0 > "${NETCONS_PATH}"/enabled 2> /dev/null || true
+		# Try to enable a bit harder, given it might fail to enable
+		# Write to `enabled` might fail depending on the lock, which is
+		# highly contentious here
+		for _ in $(seq 5)
+		do
+			echo 1 > "${NETCONS_PATH}"/enabled 2> /dev/null || true
+		done
+	done
+}
+
+toggle_iface(){
+	ip link set "${SRCIF}" down
+	ip link set "${SRCIF}" up
+}
+
+# Start here
+
+modprobe netdevsim 2> /dev/null || true
+modprobe netconsole 2> /dev/null || true
+
+# Check for basic system dependency and exit if not found
+check_for_dependencies
+# Set current loglevel to KERN_INFO(6), and default to KERN_NOTICE(5)
+echo "6 5" > /proc/sys/kernel/printk
+# Remove the namespace, interfaces and netconsole target on exit
+trap cleanup EXIT
+# Create one namespace and two interfaces
+set_network "${IP_VERSION}"
+# Create a dynamic target for netconsole
+create_dynamic_target "${FORMAT}"
+
+for i in $(seq "$ITERATIONS")
+do
+	for _ in $(seq 10)
+	do
+		echo "${MSG}: ${TARGET} ${i}" > /dev/kmsg
+	done
+	wait
+
+	if (( i % 30 == 0 )); then
+		toggle_netcons_target &
+	fi
+
+	if (( i % 50 == 0 )); then
+		# create some targets, enable them, send msg and disable
+		# all in a parallel thread
+		create_and_delete_random_target &
+	fi
+
+	if (( i % 70 == 0 )); then
+		toggle_iface &
+	fi
+done
+wait
+
+exit "${EXIT_STATUS}"

-- 
2.47.3

[PATCH net v5 4/4] selftest: netcons: add test for netconsole over bonded interfaces

[Breno Leitao]

This patch adds a selftest that verifies netconsole functionality
over bonded network interfaces using netdevsim. It sets up two bonded
interfaces acting as transmit (TX) and receive (RX) ends, placed in
separate network namespaces. The test sends kernel log messages and
verifies that they are properly received on the bonded RX interfaces
with both IPv4 and IPv6, and using basic and extended netconsole
formats.

This patchset aims to test a long-standing netpoll are where netpoll has
multiple users. (in this case netconsole and bonding). A similar
selftest has been discussed in [1] and [2].

This depends on CONFIG_BONDING, set it, given it is not set in
kernel/configs/debug.config.
NIPA uses the following command:
 $ vng -v -b -f kernel/configs/debug.config -f tools/testing/selftests/drivers/net/config

Link: https://lore.kernel.org/all/20250905-netconsole_torture-v3-0-875c7febd316@debian.org/ [1]
Link: https://lore.kernel.org/lkml/96b940137a50e5c387687bb4f57de8b0435a653f.1404857349.git.decot@googlers.com/ [2]
Signed-off-by: Breno Leitao <leitao@debian.org>
---
 tools/testing/selftests/drivers/net/Makefile       |   1 +
 tools/testing/selftests/drivers/net/config         |   1 +
 .../selftests/drivers/net/lib/sh/lib_netcons.sh    | 167 +++++++++++++++++++--
 .../selftests/drivers/net/netcons_over_bonding.sh  |  76 ++++++++++
 4 files changed, 233 insertions(+), 12 deletions(-)

diff --git a/tools/testing/selftests/drivers/net/Makefile b/tools/testing/selftests/drivers/net/Makefile
index 2b253b1ff4f38..b49730b393bdc 100644
--- a/tools/testing/selftests/drivers/net/Makefile
+++ b/tools/testing/selftests/drivers/net/Makefile
@@ -15,6 +15,7 @@ TEST_PROGS := \
 	netcons_basic.sh \
 	netcons_cmdline.sh \
 	netcons_fragmented_msg.sh \
+	netcons_over_bonding.sh \
 	netcons_overflow.sh \
 	netcons_sysdata.sh \
 	netcons_torture.sh \
diff --git a/tools/testing/selftests/drivers/net/config b/tools/testing/selftests/drivers/net/config
index f27172ddee0a1..dfa8d3291ce0e 100644
--- a/tools/testing/selftests/drivers/net/config
+++ b/tools/testing/selftests/drivers/net/config
@@ -1,6 +1,7 @@
 CONFIG_IPV6=y
 CONFIG_NETDEVSIM=m
 CONFIG_CONFIGFS_FS=y
+CONFIG_BONDING=m
 CONFIG_NETCONSOLE=m
 CONFIG_NETCONSOLE_DYNAMIC=y
 CONFIG_NETCONSOLE_EXTENDED_LOG=y
diff --git a/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh b/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
index 9b5ef8074440c..b9436f29ddf29 100644
--- a/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
+++ b/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
@@ -28,17 +28,24 @@ NETCONS_PATH="${NETCONS_CONFIGFS}"/"${TARGET}"
 # NAMESPACE will be populated by setup_ns with a random value
 NAMESPACE=""
 
-# IDs for netdevsim
+# IDs for netdevsim. We either use NSIM_DEV_{1,2}_ID for standard test
+# or NSIM_BOND_{T,R}X_{1,2} for the bonding tests. Not both at the
+# same time.
 NSIM_DEV_1_ID=$((256 + RANDOM % 256))
 NSIM_DEV_2_ID=$((512 + RANDOM % 256))
+NSIM_BOND_TX_1=$((768 + RANDOM % 256))
+NSIM_BOND_TX_2=$((1024 + RANDOM % 256))
+NSIM_BOND_RX_1=$((1280 + RANDOM % 256))
+NSIM_BOND_RX_2=$((1536 + RANDOM % 256))
 NSIM_DEV_SYS_NEW="/sys/bus/netdevsim/new_device"
+NSIM_DEV_SYS_LINK="/sys/bus/netdevsim/link_device"
+NSIM_DEV_SYS_DEL="/sys/bus/netdevsim/del_device"
 
 # Used to create and delete namespaces
 source "${LIBDIR}"/../../../../net/lib.sh
 
 # Create netdevsim interfaces
 create_ifaces() {
-
 	echo "$NSIM_DEV_2_ID" > "$NSIM_DEV_SYS_NEW"
 	echo "$NSIM_DEV_1_ID" > "$NSIM_DEV_SYS_NEW"
 	udevadm settle 2> /dev/null || true
@@ -54,7 +61,6 @@ create_ifaces() {
 }
 
 link_ifaces() {
-	local NSIM_DEV_SYS_LINK="/sys/bus/netdevsim/link_device"
 	local SRCIF_IFIDX=$(cat /sys/class/net/"$SRCIF"/ifindex)
 	local DSTIF_IFIDX=$(cat /sys/class/net/"$DSTIF"/ifindex)
 
@@ -96,18 +102,60 @@ function select_ipv4_or_ipv6()
 	fi
 }
 
+# Create 4 netdevsim interfaces. Two of them will be bound to TX bonding iface
+# and the other two will be bond to the RX interface (on the other namespace)
+function create_ifaces_bond() {
+	echo "$NSIM_BOND_TX_1" > "$NSIM_DEV_SYS_NEW"
+	echo "$NSIM_BOND_TX_2" > "$NSIM_DEV_SYS_NEW"
+	echo "$NSIM_BOND_RX_1" > "$NSIM_DEV_SYS_NEW"
+	echo "$NSIM_BOND_RX_2" > "$NSIM_DEV_SYS_NEW"
+	udevadm settle 2> /dev/null || true
+
+	local BOND_TX1=/sys/bus/netdevsim/devices/netdevsim"$NSIM_BOND_TX_1"
+	local BOND_TX2=/sys/bus/netdevsim/devices/netdevsim"$NSIM_BOND_TX_2"
+	local BOND_RX1=/sys/bus/netdevsim/devices/netdevsim"$NSIM_BOND_RX_1"
+	local BOND_RX2=/sys/bus/netdevsim/devices/netdevsim"$NSIM_BOND_RX_2"
+
+	# TX
+	BOND_TX1_IF=$(find "$BOND_TX1"/net -maxdepth 1 -type d ! \
+		-path "$BOND_TX1"/net -exec basename {} \; | grep -v net)
+	BOND_TX2_IF=$(find "$BOND_TX2"/net -maxdepth 1 -type d ! \
+		-path "$BOND_TX2"/net -exec basename {} \; | grep -v net)
+
+	# RX
+	BOND_RX1_IF=$(find "$BOND_RX1"/net -maxdepth 1 -type d ! \
+		-path "$BOND_RX1"/net -exec basename {} \; | grep -v net)
+	BOND_RX2_IF=$(find "$BOND_RX2"/net -maxdepth 1 -type d ! \
+		-path "$BOND_RX2"/net -exec basename {} \; | grep -v net)
+}
+
 function set_network() {
 	local IP_VERSION=${1:-"ipv4"}
+	local MODE=${2:-"standard"}
 
 	# setup_ns function is coming from lib.sh
 	setup_ns NAMESPACE
 
-	# Create both interfaces, and assign the destination to a different
-	# namespace
-	create_ifaces
+	if [[  "${MODE}" == "bonding" ]]
+	then
+		# Create two interfaces for RX and two for TX
+		create_ifaces_bond
+		# Link netlink ifaces
+		link_ifaces_bond
+		# Bind the TX ifaces into BONDTX_IF and the receive ifaces
+		# into BONDRX_IF
+		setup_bonding_ifaces
+	else
+		# Create both interfaces, and assign the destination to
+		# a different namespace
+		create_ifaces
 
-	# Link both interfaces back to back
-	link_ifaces
+		# Link both interfaces back to back
+		link_ifaces
+	fi
+	# Here after SRCIF and DSTIF are configured to either
+	# regular interfaces or bonding interfaces, and will be treated
+	# the same.
 
 	select_ipv4_or_ipv6 "${IP_VERSION}"
 	configure_ip
@@ -180,8 +228,6 @@ function disable_release_append() {
 }
 
 function do_cleanup() {
-	local NSIM_DEV_SYS_DEL="/sys/bus/netdevsim/del_device"
-
 	# Delete netdevsim devices
 	echo "$NSIM_DEV_2_ID" > "$NSIM_DEV_SYS_DEL"
 	echo "$NSIM_DEV_1_ID" > "$NSIM_DEV_SYS_DEL"
@@ -193,14 +239,18 @@ function do_cleanup() {
 	echo "${DEFAULT_PRINTK_VALUES}" > /proc/sys/kernel/printk
 }
 
-function cleanup() {
+function cleanup_netcons() {
 	# delete netconsole dynamic reconfiguration
-	echo 0 > "${NETCONS_PATH}"/enabled
+	# do not fail if the target is already disabled
+	echo 0 > "${NETCONS_PATH}"/enabled || true
 	# Remove all the keys that got created during the selftest
 	find "${NETCONS_PATH}/userdata/" -mindepth 1 -type d -delete
 	# Remove the configfs entry
 	rmdir "${NETCONS_PATH}"
+}
 
+function cleanup() {
+	cleanup_netcons
 	do_cleanup
 }
 
@@ -377,3 +427,96 @@ function wait_for_port() {
 	# more frequently on IPv6
 	sleep 1
 }
+
+# netdevsim link BOND_TX to BOND_RX interfaces
+function link_ifaces_bond() {
+	local BOND_TX1_IFIDX
+	local BOND_TX2_IFIDX
+	local BOND_RX1_IFIDX
+	local BOND_RX2_IFIDX
+
+	BOND_TX1_IFIDX=$(cat /sys/class/net/"$BOND_TX1_IF"/ifindex)
+	BOND_TX2_IFIDX=$(cat /sys/class/net/"$BOND_TX2_IF"/ifindex)
+	BOND_RX1_IFIDX=$(cat /sys/class/net/"$BOND_RX1_IF"/ifindex)
+	BOND_RX2_IFIDX=$(cat /sys/class/net/"$BOND_RX2_IF"/ifindex)
+
+	exec {NAMESPACE_FD}</var/run/netns/"${NAMESPACE}"
+	exec {INITNS_FD}</proc/self/ns/net
+
+	# Bind the dst interfaces to namespace
+	ip link set "${BOND_RX1_IF}" netns "${NAMESPACE}"
+	ip link set "${BOND_RX2_IF}" netns "${NAMESPACE}"
+
+	# Linking TX ifaces to the RX ones (on the other namespace}
+	echo "${INITNS_FD}:$BOND_TX1_IFIDX $NAMESPACE_FD:$BOND_RX1_IFIDX"  \
+		> "$NSIM_DEV_SYS_LINK"
+	echo "${INITNS_FD}:$BOND_TX2_IFIDX $NAMESPACE_FD:$BOND_RX2_IFIDX"  \
+		> "$NSIM_DEV_SYS_LINK"
+}
+
+# Create "bond_tx_XX" and "bond_rx_XX" interfaces, and set DSTIF and SRCIF with
+# the bonding interfaces
+function setup_bonding_ifaces() {
+	local RAND=$(( RANDOM % 100 ))
+	BONDTX_IF="bond_tx_$RAND"
+	BONDRX_IF="bond_rx_$RAND"
+
+	if ! ip link add "${BONDTX_IF}" type bond mode balance-rr
+	then
+		echo "Failed to create bond TX interface. Is CONFIG_BONDING set?" >&2
+		# only clean nsim ifaces and namespace. Nothing else has been
+		# initialized
+		cleanup_bond_nsim
+		trap - EXIT
+		exit "${ksft_skip}"
+	fi
+	ip link set "${BOND_TX1_IF}" master "${BONDTX_IF}"
+	ip link set "${BOND_TX2_IF}" master "${BONDTX_IF}"
+	ip link set "${BONDTX_IF}" up
+
+	# now create the RX bonding iface
+	ip netns exec "${NAMESPACE}" \
+		ip link add "${BONDRX_IF}" type bond mode balance-rr
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BOND_RX1_IF}" master "${BONDRX_IF}"
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BOND_RX2_IF}" master "${BONDRX_IF}"
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BONDRX_IF}" up
+
+	# from here after, SRCIF is bond interface
+	SRCIF="${BONDTX_IF}"
+	DSTIF="${BONDRX_IF}"
+}
+
+# Clean up netdevsim ifaces created for bonding test
+function cleanup_bond_nsim() {
+	echo "$NSIM_BOND_TX_1" > "$NSIM_DEV_SYS_DEL"
+	echo "$NSIM_BOND_TX_2" > "$NSIM_DEV_SYS_DEL"
+	echo "$NSIM_BOND_RX_1" > "$NSIM_DEV_SYS_DEL"
+	echo "$NSIM_BOND_RX_2" > "$NSIM_DEV_SYS_DEL"
+	cleanup_all_ns
+}
+
+# Full cleanup
+function cleanup_bond() {
+	cleanup_netcons
+
+	# Delete TX ifaces
+	ip link set "${BONDTX_IF}" down || true
+	ip link set "${BOND_TX1_IF}" down || true
+	ip link set "${BOND_TX2_IF}" down || true
+	ip link delete "${BONDTX_IF}" type bond  || true
+
+	# Delete RX ifaces
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BONDRX_IF}" down || true
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BOND_RX1_IF}" down || true
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BOND_RX2_IF}" down || true
+	ip netns exec "${NAMESPACE}" \
+		ip link delete "${BONDRX_IF}" type bond  || true
+
+	cleanup_bond_nsim
+}
diff --git a/tools/testing/selftests/drivers/net/netcons_over_bonding.sh b/tools/testing/selftests/drivers/net/netcons_over_bonding.sh
new file mode 100755
index 0000000000000..10f2183a16edb
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/netcons_over_bonding.sh
@@ -0,0 +1,76 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: GPL-2.0
+# This test verifies netconsole functionality over a bonded network setup.
+#
+# Four interfaces are created using netdevsim; two of them are bonded to serve
+# as the netconsole's transmit interface. The remaining two interfaces are
+# similarly bonded and assigned to a separate network namespace, which acts as
+# the receive interface, where socat monitors for incoming messages.
+#
+# A netconsole message is then sent to ensure it is properly received across
+# this configuration.
+#
+# The test's objective is to exercise netpoll usage when managed simultaneously
+# by multiple subsystems (netconsole and bonding).
+#
+# Author: Breno Leitao <leitao@debian.org>
+
+set -euo pipefail
+
+SCRIPTDIR=$(dirname "$(readlink -e "${BASH_SOURCE[0]}")")
+
+source "${SCRIPTDIR}"/lib/sh/lib_netcons.sh
+
+modprobe netdevsim 2> /dev/null || true
+modprobe netconsole 2> /dev/null || true
+modprobe bonding 2> /dev/null || true
+
+# The content of kmsg will be save to the following file
+OUTPUT_FILE="/tmp/${TARGET}"
+
+# Check for basic system dependency and exit if not found
+check_for_dependencies
+# Set current loglevel to KERN_INFO(6), and default to KERN_NOTICE(5)
+echo "6 5" > /proc/sys/kernel/printk
+# Remove the namespace, interfaces and netconsole target on exit
+trap cleanup_bond EXIT
+
+# Run the test twice, with different format modes
+for FORMAT in "basic" "extended"
+do
+	for IP_VERSION in "ipv6" "ipv4"
+	do
+		# Run the test twice, with different format modes
+		echo "Running netcons over bonding ifaces: ${FORMAT} (${IP_VERSION})"
+
+		# Create one namespace and two interfaces
+		set_network "${IP_VERSION}" "bonding"
+		# Create a dynamic target for netconsole
+		create_dynamic_target "${FORMAT}"
+		# Only set userdata for extended format
+		if [ "$FORMAT" == "extended" ]
+		then
+			# Set userdata "key" with the "value" value
+			set_user_data
+		fi
+		# Listed for netconsole port inside the namespace and
+		# destination interface
+		listen_port_and_save_to "${OUTPUT_FILE}" "${IP_VERSION}" &
+		# Wait for socat to start and listen to the port.
+		wait_for_port "${NAMESPACE}" "${PORT}" "${IP_VERSION}"
+		# Send the message
+		echo "${MSG}: ${TARGET}" > /dev/kmsg
+		# Wait until socat saves the file to disk
+		busywait "${BUSYWAIT_TIMEOUT}" test -s "${OUTPUT_FILE}"
+		# Make sure the message was received in the dst part
+		# and exit
+		validate_result "${OUTPUT_FILE}" "${FORMAT}"
+		# kill socat in case it is still running
+		pkill_socat
+		cleanup_bond
+		echo "bonding: ${FORMAT} : ${IP_VERSION} : Test passed" >&2
+	done
+done
+
+trap - EXIT
+exit "${EXIT_STATUS}"

-- 
2.47.3

Re: [PATCH net v5 4/4] selftest: netcons: add test for netconsole over bonded interfaces

[Jakub Kicinski]

On Thu, 18 Sep 2025 03:42:08 -0700 Breno Leitao wrote:
> This patch adds a selftest that verifies netconsole functionality
> over bonded network interfaces using netdevsim. It sets up two bonded
> interfaces acting as transmit (TX) and receive (RX) ends, placed in
> separate network namespaces. The test sends kernel log messages and
> verifies that they are properly received on the bonded RX interfaces
> with both IPv4 and IPv6, and using basic and extended netconsole
> formats.

I'm not great at reading bash but I don't think this tests what we care
about. We want to test bonding's special ability to propagate a netpoll
instances onto its sub-interfaces. So you should be trying to test
different orders of setting and disabling netpoll on the bond and its
sub-interfaces (while the other is setup path is also active).

Since the bonding tests can't run on real HW it can't live directly in
tools/testing/selftests/drivers/net/ we need to move it to either the
netdevsim group or the bonding group.

Re: [PATCH net v5 4/4] selftest: netcons: add test for netconsole over bonded interfaces

[Breno Leitao]

Hello Jakub,

On Fri, Sep 19, 2025 at 05:49:01PM -0700, Jakub Kicinski wrote:
> On Thu, 18 Sep 2025 03:42:08 -0700 Breno Leitao wrote:
> > This patch adds a selftest that verifies netconsole functionality
> > over bonded network interfaces using netdevsim. It sets up two bonded
> > interfaces acting as transmit (TX) and receive (RX) ends, placed in
> > separate network namespaces. The test sends kernel log messages and
> > verifies that they are properly received on the bonded RX interfaces
> > with both IPv4 and IPv6, and using basic and extended netconsole
> > formats.
> 
> I'm not great at reading bash but I don't think this tests what we care
> about. We want to test bonding's special ability to propagate a netpoll
> instances onto its sub-interfaces. So you should be trying to test
> different orders of setting and disabling netpoll on the bond and its
> sub-interfaces (while the other is setup path is also active).

Ack. I am extending the test, to try to enable netpoll/netconsole on a
sub-interface, which should fail. It should not be possible to have
netconsole in an sub-interface

Prohibiting a sub-interface from having netpoll was added a while ago by
0c1ad04aecb975 ("netpoll: prevent netpoll setup on slave devices")

So, my suggestion is:

1) test netpoll/netconsole on a bonding interface
2) Try to setup netconsole on a sub-interface (and it should fail)
3) remove the sub-interface from the bonding interface, and netconsole/netpoll setup
should succeed.

> Since the bonding tests can't run on real HW it can't live directly in
> tools/testing/selftests/drivers/net/ we need to move it to either the
> netdevsim group or the bonding group.

Are you talking abouttools/testing/selftests/drivers/net/bonding as the
bonding group?

With the changed above, this is how the selftest looks like now:

Author: Breno Leitao <leitao@debian.org>
Date:   Wed Sep 17 01:46:26 2025 -0700

    selftest: netcons: add test for netconsole over bonded interfaces
    
    This patch adds a selftest that verifies netconsole functionality
    over bonded network interfaces using netdevsim. It sets up two bonded
    interfaces acting as transmit (TX) and receive (RX) ends, placed in
    separate network namespaces. The test sends kernel log messages and
    verifies that they are properly received on the bonded RX interfaces
    with both IPv4 and IPv6, and using basic and extended netconsole
    formats.
    
    This patchset aims to test a long-standing netpoll are where netpoll has
    multiple users. (in this case netconsole and bonding). A similar
    selftest has been discussed in [1] and [2].
    
    This test also try to enable bonding and netpoll at the same time, and
    make sure that it fails.
    
    Link: https://lore.kernel.org/all/20250905-netconsole_torture-v3-0-875c7febd316@debian.org/ [1]
    Link: https://lore.kernel.org/lkml/96b940137a50e5c387687bb4f57de8b0435a653f.1404857349.git.decot@googlers.com/ [2]
    Signed-off-by: Breno Leitao <leitao@debian.org>

diff --git a/tools/testing/selftests/drivers/net/bonding/Makefile b/tools/testing/selftests/drivers/net/bonding/Makefile
index 3462783ed3aca..d7fb239c02814 100644
--- a/tools/testing/selftests/drivers/net/bonding/Makefile
+++ b/tools/testing/selftests/drivers/net/bonding/Makefile
@@ -8,6 +8,7 @@ TEST_PROGS := \
 	dev_addr_lists.sh \
 	mode-1-recovery-updelay.sh \
 	mode-2-recovery-updelay.sh \
+	netcons_over_bonding.sh \
 	bond_options.sh \
 	bond-eth-type-change.sh \
 	bond_macvlan_ipvlan.sh \
diff --git a/tools/testing/selftests/drivers/net/bonding/config b/tools/testing/selftests/drivers/net/bonding/config
index 4d16a69ffc650..c9e609ff5b5dd 100644
--- a/tools/testing/selftests/drivers/net/bonding/config
+++ b/tools/testing/selftests/drivers/net/bonding/config
@@ -10,3 +10,8 @@ CONFIG_NET_CLS_MATCHALL=m
 CONFIG_NET_SCH_INGRESS=y
 CONFIG_NLMON=y
 CONFIG_VETH=y
+CONFIG_NETDEVSIM=m
+CONFIG_CONFIGFS_FS=y
+CONFIG_NETCONSOLE=m
+CONFIG_NETCONSOLE_DYNAMIC=y
+CONFIG_NETCONSOLE_EXTENDED_LOG=y
diff --git a/tools/testing/selftests/drivers/net/bonding/netcons_over_bonding.sh b/tools/testing/selftests/drivers/net/bonding/netcons_over_bonding.sh
new file mode 100755
index 0000000000000..f80e29152a35b
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/bonding/netcons_over_bonding.sh
@@ -0,0 +1,156 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# This test verifies netconsole functionality over a bonded network setup.
+#
+# Four interfaces are created using netdevsim; two of them are bonded to serve
+# as the netconsole's transmit interface. The remaining two interfaces are
+# similarly bonded and assigned to a separate network namespace, which acts as
+# the receive interface, where socat monitors for incoming messages.
+#
+# A netconsole message is then sent to ensure it is properly received across
+# this configuration.
+#
+# Later, try to enable netconsole on an interface that is part of a bonding
+# interface, which should fail.
+#
+# The test's objective is to exercise netpoll usage when managed simultaneously
+# by multiple subsystems (netconsole and bonding).
+#
+# Author: Breno Leitao <leitao@debian.org>
+
+set -euo pipefail
+
+SCRIPTDIR=$(dirname "$(readlink -e "${BASH_SOURCE[0]}")")
+
+source "${SCRIPTDIR}"/../lib/sh/lib_netcons.sh
+
+modprobe netdevsim 2> /dev/null || true
+modprobe netconsole 2> /dev/null || true
+modprobe bonding 2> /dev/null || true
+
+# The content of kmsg will be save to the following file
+OUTPUT_FILE="/tmp/${TARGET}"
+
+# Check for basic system dependency and exit if not found
+check_for_dependencies
+# Set current loglevel to KERN_INFO(6), and default to KERN_NOTICE(5)
+echo "6 5" > /proc/sys/kernel/printk
+# Remove the namespace, interfaces and netconsole target on exit
+trap cleanup_bond EXIT
+
+FORMAT="extended"
+IP_VERSION="ipv6"
+
+function create_all_ifaces() {
+	# setup_ns function is coming from lib.sh
+	setup_ns NAMESPACE
+
+	# Create two interfaces for RX and two for TX
+	create_ifaces_bond
+	# Link netlink ifaces
+	link_ifaces_bond
+}
+
+# configure DSTIF and SRCIF IPs
+function configure_ifaces_ips() {
+	local IP_VERSION=${1:-"ipv4"}
+	select_ipv4_or_ipv6 "${IP_VERSION}"
+	configure_ip
+}
+
+function enable_netpoll_on_enslaved_iface() {
+	echo 0 > "${NETCONS_PATH}"/enabled
+
+	# At this stage, BOND_TX1_IF is enslaved to BONDTX_IF, and linked to
+	# BOND_RX1_IF inside the namespace.
+	echo "${BOND_TX1_IF}" > "${NETCONS_PATH}"/dev_name
+
+	# This should fail with the following message in dmesg:
+	# netpoll: netconsole: ethX is a slave device, aborting
+	set +e
+	echo 1 > "${NETCONS_PATH}"/enabled
+	set -e
+
+	if [ "$(cat "${NETCONS_PATH}/enabled")" -eq 1 ]
+	then
+		echo "netpoll: Bonding and netpoll cannot co-exists. Test failed." >&2
+		exit "${ksft_fail}"
+
+	fi
+}
+
+function delete_bond_and_reenable_target() {
+	ip link delete "${BONDTX_IF}" type bond
+
+	# BOND_TX1_IF is not attached to a bond interface anymore
+	# netpoll can be plugged in there
+	echo "${BOND_TX1_IF}" > "${NETCONS_PATH}"/dev_name
+
+	# this should work, since the interface is not enslaved
+	echo 1 > "${NETCONS_PATH}"/enabled
+
+	if [ "$(cat "${NETCONS_PATH}/enabled")" -eq 0 ]
+	then
+		echo "netpoll: Unable to start netpoll on an unbond iface. Test failed." >&2
+		exit "${ksft_fail}"
+
+	fi
+}
+
+function send_netcons_msg_through_bond_iface() {
+
+	# Listed for netconsole port inside the namespace and
+	# destination interface
+	listen_port_and_save_to "${OUTPUT_FILE}" "${IP_VERSION}" &
+	# Wait for socat to start and listen to the port.
+	wait_for_port "${NAMESPACE}" "${PORT}" "${IP_VERSION}"
+	# Send the message
+	echo "${MSG}: ${TARGET}" > /dev/kmsg
+	# Wait until socat saves the file to disk
+	busywait "${BUSYWAIT_TIMEOUT}" test -s "${OUTPUT_FILE}"
+	# Make sure the message was received in the dst part
+	# and exit
+	validate_result "${OUTPUT_FILE}" "${FORMAT}"
+	# kill socat in case it is still running
+	pkill_socat
+}
+
+# Tests start here
+
+# Create one namespace and two interfaces
+create_all_ifaces
+
+# then bind the interfaces with netpoll attached
+setup_bonding_ifaces
+
+# First test send a msg through bonding
+DSTIF="${BONDRX_IF}"
+SRCIF="${BONDTX_IF}"
+
+# Configure the ips as BOND_RX1_IF and BOND_TX1_IF
+configure_ifaces_ips "${IP_VERSION}"
+create_dynamic_target "${FORMAT}"
+set_user_data
+
+# Test #1
+# Create an bonding interface and attach netpoll into
+# the bonding interface. Netconsole/netpoll should work on
+# the bonding interface.
+send_netcons_msg_through_bond_iface
+echo "test #1: netpoll on bonding interface worked. Test passed" >&2
+
+# Test #2.
+# Try to attach netpoll to an enslaved interface (while still being part of a
+# bonding interface), which shouldn't be allowed
+enable_netpoll_on_enslaved_iface
+echo "test #2: netpoll correctly rejected enslaved interface (expected behavior). Test passed." >&2
+
+# Test #3
+# Detach the interface from a bonding interface and attach netpoll again
+delete_bond_and_reenable_target
+echo "test #3: Able to attach to an unbound interface. Test passed." >&2
+
+cleanup_bond
+trap - EXIT
+exit "${EXIT_STATUS}"
diff --git a/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh b/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
index 9b5ef8074440c..4862d025b7c74 100644
--- a/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
+++ b/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
@@ -28,17 +28,24 @@ NETCONS_PATH="${NETCONS_CONFIGFS}"/"${TARGET}"
 # NAMESPACE will be populated by setup_ns with a random value
 NAMESPACE=""
 
-# IDs for netdevsim
+# IDs for netdevsim. We either use NSIM_DEV_{1,2}_ID for standard test
+# or NSIM_BOND_{T,R}X_{1,2} for the bonding tests. Not both at the
+# same time.
 NSIM_DEV_1_ID=$((256 + RANDOM % 256))
 NSIM_DEV_2_ID=$((512 + RANDOM % 256))
+NSIM_BOND_TX_1=$((768 + RANDOM % 256))
+NSIM_BOND_TX_2=$((1024 + RANDOM % 256))
+NSIM_BOND_RX_1=$((1280 + RANDOM % 256))
+NSIM_BOND_RX_2=$((1536 + RANDOM % 256))
 NSIM_DEV_SYS_NEW="/sys/bus/netdevsim/new_device"
+NSIM_DEV_SYS_LINK="/sys/bus/netdevsim/link_device"
+NSIM_DEV_SYS_DEL="/sys/bus/netdevsim/del_device"
 
 # Used to create and delete namespaces
 source "${LIBDIR}"/../../../../net/lib.sh
 
 # Create netdevsim interfaces
 create_ifaces() {
-
 	echo "$NSIM_DEV_2_ID" > "$NSIM_DEV_SYS_NEW"
 	echo "$NSIM_DEV_1_ID" > "$NSIM_DEV_SYS_NEW"
 	udevadm settle 2> /dev/null || true
@@ -54,7 +61,6 @@ create_ifaces() {
 }
 
 link_ifaces() {
-	local NSIM_DEV_SYS_LINK="/sys/bus/netdevsim/link_device"
 	local SRCIF_IFIDX=$(cat /sys/class/net/"$SRCIF"/ifindex)
 	local DSTIF_IFIDX=$(cat /sys/class/net/"$DSTIF"/ifindex)
 
@@ -96,6 +102,33 @@ function select_ipv4_or_ipv6()
 	fi
 }
 
+# Create 4 netdevsim interfaces. Two of them will be bound to TX bonding iface
+# and the other two will be bond to the RX interface (on the other namespace)
+function create_ifaces_bond() {
+	echo "$NSIM_BOND_TX_1" > "$NSIM_DEV_SYS_NEW"
+	echo "$NSIM_BOND_TX_2" > "$NSIM_DEV_SYS_NEW"
+	echo "$NSIM_BOND_RX_1" > "$NSIM_DEV_SYS_NEW"
+	echo "$NSIM_BOND_RX_2" > "$NSIM_DEV_SYS_NEW"
+	udevadm settle 2> /dev/null || true
+
+	local BOND_TX1=/sys/bus/netdevsim/devices/netdevsim"$NSIM_BOND_TX_1"
+	local BOND_TX2=/sys/bus/netdevsim/devices/netdevsim"$NSIM_BOND_TX_2"
+	local BOND_RX1=/sys/bus/netdevsim/devices/netdevsim"$NSIM_BOND_RX_1"
+	local BOND_RX2=/sys/bus/netdevsim/devices/netdevsim"$NSIM_BOND_RX_2"
+
+	# TX
+	BOND_TX1_IF=$(find "$BOND_TX1"/net -maxdepth 1 -type d ! \
+		-path "$BOND_TX1"/net -exec basename {} \; | grep -v net)
+	BOND_TX2_IF=$(find "$BOND_TX2"/net -maxdepth 1 -type d ! \
+		-path "$BOND_TX2"/net -exec basename {} \; | grep -v net)
+
+	# RX
+	BOND_RX1_IF=$(find "$BOND_RX1"/net -maxdepth 1 -type d ! \
+		-path "$BOND_RX1"/net -exec basename {} \; | grep -v net)
+	BOND_RX2_IF=$(find "$BOND_RX2"/net -maxdepth 1 -type d ! \
+		-path "$BOND_RX2"/net -exec basename {} \; | grep -v net)
+}
+
 function set_network() {
 	local IP_VERSION=${1:-"ipv4"}
 
@@ -180,8 +213,6 @@ function disable_release_append() {
 }
 
 function do_cleanup() {
-	local NSIM_DEV_SYS_DEL="/sys/bus/netdevsim/del_device"
-
 	# Delete netdevsim devices
 	echo "$NSIM_DEV_2_ID" > "$NSIM_DEV_SYS_DEL"
 	echo "$NSIM_DEV_1_ID" > "$NSIM_DEV_SYS_DEL"
@@ -193,14 +224,26 @@ function do_cleanup() {
 	echo "${DEFAULT_PRINTK_VALUES}" > /proc/sys/kernel/printk
 }
 
-function cleanup() {
+function cleanup_netcons() {
 	# delete netconsole dynamic reconfiguration
-	echo 0 > "${NETCONS_PATH}"/enabled
+	# do not fail if the target is already disabled
+	if [[ ! -d "${NETCONS_PATH}" ]]
+	then
+		# in some cases this is called before netcons path is created
+		return
+	fi
+	if [[ $(cat "${NETCONS_PATH}"/enabled) != 0 ]]
+	then
+		echo 0 > "${NETCONS_PATH}"/enabled || true
+	fi
 	# Remove all the keys that got created during the selftest
 	find "${NETCONS_PATH}/userdata/" -mindepth 1 -type d -delete
 	# Remove the configfs entry
 	rmdir "${NETCONS_PATH}"
+}
 
+function cleanup() {
+	cleanup_netcons
 	do_cleanup
 }
 
@@ -377,3 +420,105 @@ function wait_for_port() {
 	# more frequently on IPv6
 	sleep 1
 }
+
+# netdevsim link BOND_TX to BOND_RX interfaces
+function link_ifaces_bond() {
+	local BOND_TX1_IFIDX
+	local BOND_TX2_IFIDX
+	local BOND_RX1_IFIDX
+	local BOND_RX2_IFIDX
+
+	BOND_TX1_IFIDX=$(cat /sys/class/net/"$BOND_TX1_IF"/ifindex)
+	BOND_TX2_IFIDX=$(cat /sys/class/net/"$BOND_TX2_IF"/ifindex)
+	BOND_RX1_IFIDX=$(cat /sys/class/net/"$BOND_RX1_IF"/ifindex)
+	BOND_RX2_IFIDX=$(cat /sys/class/net/"$BOND_RX2_IF"/ifindex)
+
+	exec {NAMESPACE_FD}</var/run/netns/"${NAMESPACE}"
+	exec {INITNS_FD}</proc/self/ns/net
+
+	# Bind the dst interfaces to namespace
+	ip link set "${BOND_RX1_IF}" netns "${NAMESPACE}"
+	ip link set "${BOND_RX2_IF}" netns "${NAMESPACE}"
+
+	# Linking TX ifaces to the RX ones (on the other namespace}
+	echo "${INITNS_FD}:$BOND_TX1_IFIDX $NAMESPACE_FD:$BOND_RX1_IFIDX"  \
+		> "$NSIM_DEV_SYS_LINK"
+	echo "${INITNS_FD}:$BOND_TX2_IFIDX $NAMESPACE_FD:$BOND_RX2_IFIDX"  \
+		> "$NSIM_DEV_SYS_LINK"
+}
+
+# Create "bond_tx_XX" and "bond_rx_XX" interfaces, and set DSTIF and SRCIF with
+# the bonding interfaces
+function setup_bonding_ifaces() {
+	local RAND=$(( RANDOM % 100 ))
+	BONDTX_IF="bond_tx_$RAND"
+	BONDRX_IF="bond_rx_$RAND"
+
+	if ! ip link add "${BONDTX_IF}" type bond mode balance-rr
+	then
+		echo "Failed to create bond TX interface. Is CONFIG_BONDING set?" >&2
+		# only clean nsim ifaces and namespace. Nothing else has been
+		# initialized
+		cleanup_bond_nsim
+		trap - EXIT
+		exit "${ksft_skip}"
+	fi
+	ip link set "${BOND_TX1_IF}" down
+	ip link set "${BOND_TX2_IF}" down
+
+	ip link set "${BOND_TX1_IF}" master "${BONDTX_IF}"
+	ip link set "${BOND_TX2_IF}" master "${BONDTX_IF}"
+	ip link set "${BONDTX_IF}" up
+
+	# now create the RX bonding iface
+	ip netns exec "${NAMESPACE}" \
+		ip link add "${BONDRX_IF}" type bond mode balance-rr
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BOND_RX1_IF}" down
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BOND_RX2_IF}" down
+
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BOND_RX1_IF}" master "${BONDRX_IF}"
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BOND_RX2_IF}" master "${BONDRX_IF}"
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BONDRX_IF}" up
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BOND_RX1_IF}" up
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BOND_RX2_IF}" up
+
+}
+
+# Clean up netdevsim ifaces created for bonding test
+function cleanup_bond_nsim() {
+	echo "$NSIM_BOND_TX_1" > "$NSIM_DEV_SYS_DEL"
+	echo "$NSIM_BOND_TX_2" > "$NSIM_DEV_SYS_DEL"
+	echo "$NSIM_BOND_RX_1" > "$NSIM_DEV_SYS_DEL"
+	echo "$NSIM_BOND_RX_2" > "$NSIM_DEV_SYS_DEL"
+	cleanup_all_ns
+}
+
+# cleanup tests that use bonding interfaces
+function cleanup_bond() {
+	cleanup_netcons
+
+	# Delete TX ifaces
+	ip link set "${BONDTX_IF}" down  2> /dev/null|| true
+	ip link set "${BOND_TX1_IF}" down || true
+	ip link set "${BOND_TX2_IF}" down || true
+	ip link delete "${BONDTX_IF}" type bond  2> /dev/null || true
+
+	# Delete RX ifaces
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BONDRX_IF}" down || true
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BOND_RX1_IF}" down || true
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BOND_RX2_IF}" down || true
+	ip netns exec "${NAMESPACE}" \
+		ip link delete "${BONDRX_IF}" type bond  || true
+
+	cleanup_bond_nsim
+}

Re: [PATCH net v5 4/4] selftest: netcons: add test for netconsole over bonded interfaces

[Jakub Kicinski]

On Fri, 26 Sep 2025 07:06:50 -0700 Breno Leitao wrote:
> > Since the bonding tests can't run on real HW it can't live directly in
> > tools/testing/selftests/drivers/net/ we need to move it to either the
> > netdevsim group or the bonding group.  
> 
> Are you talking abouttools/testing/selftests/drivers/net/bonding as the
> bonding group?
> 
> With the changed above, this is how the selftest looks like now:
> 
> Author: Breno Leitao <leitao@debian.org>
> Date:   Wed Sep 17 01:46:26 2025 -0700
> 
>     selftest: netcons: add test for netconsole over bonded interfaces
>     
>     This patch adds a selftest that verifies netconsole functionality
>     over bonded network interfaces using netdevsim. It sets up two bonded
>     interfaces acting as transmit (TX) and receive (RX) ends, placed in
>     separate network namespaces. The test sends kernel log messages and
>     verifies that they are properly received on the bonded RX interfaces
>     with both IPv4 and IPv6, and using basic and extended netconsole
>     formats.
>     
>     This patchset aims to test a long-standing netpoll are where netpoll has
>     multiple users. (in this case netconsole and bonding). A similar
>     selftest has been discussed in [1] and [2].
>     
>     This test also try to enable bonding and netpoll at the same time, and
>     make sure that it fails.
>     
>     Link: https://lore.kernel.org/all/20250905-netconsole_torture-v3-0-875c7febd316@debian.org/ [1]
>     Link: https://lore.kernel.org/lkml/96b940137a50e5c387687bb4f57de8b0435a653f.1404857349.git.decot@googlers.com/ [2]
>     Signed-off-by: Breno Leitao <leitao@debian.org>
> 
> diff --git a/tools/testing/selftests/drivers/net/bonding/Makefile b/tools/testing/selftests/drivers/net/bonding/Makefile
> index 3462783ed3aca..d7fb239c02814 100644
> --- a/tools/testing/selftests/drivers/net/bonding/Makefile
> +++ b/tools/testing/selftests/drivers/net/bonding/Makefile
> @@ -8,6 +8,7 @@ TEST_PROGS := \
>  	dev_addr_lists.sh \
>  	mode-1-recovery-updelay.sh \
>  	mode-2-recovery-updelay.sh \
> +	netcons_over_bonding.sh \
>  	bond_options.sh \
>  	bond-eth-type-change.sh \
>  	bond_macvlan_ipvlan.sh \

Do we need to add the netcons lib to TEST_INCLUDES  ?

> diff --git a/tools/testing/selftests/drivers/net/bonding/config b/tools/testing/selftests/drivers/net/bonding/config
> index 4d16a69ffc650..c9e609ff5b5dd 100644
> --- a/tools/testing/selftests/drivers/net/bonding/config
> +++ b/tools/testing/selftests/drivers/net/bonding/config
> @@ -10,3 +10,8 @@ CONFIG_NET_CLS_MATCHALL=m
>  CONFIG_NET_SCH_INGRESS=y
>  CONFIG_NLMON=y
>  CONFIG_VETH=y
> +CONFIG_NETDEVSIM=m
> +CONFIG_CONFIGFS_FS=y
> +CONFIG_NETCONSOLE=m
> +CONFIG_NETCONSOLE_DYNAMIC=y
> +CONFIG_NETCONSOLE_EXTENDED_LOG=y

For the config options some approximation of alphabetical sort is good.
Adding at the end increases the risk of cherry-pick / merge conflicts
dramatically.

> +function enable_netpoll_on_enslaved_iface() {
> +	echo 0 > "${NETCONS_PATH}"/enabled
> +
> +	# At this stage, BOND_TX1_IF is enslaved to BONDTX_IF, and linked to
> +	# BOND_RX1_IF inside the namespace.
> +	echo "${BOND_TX1_IF}" > "${NETCONS_PATH}"/dev_name
> +
> +	# This should fail with the following message in dmesg:
> +	# netpoll: netconsole: ethX is a slave device, aborting
> +	set +e
> +	echo 1 > "${NETCONS_PATH}"/enabled
> +	set -e
> +
> +	if [ "$(cat "${NETCONS_PATH}/enabled")" -eq 1 ]
> +	then
> +		echo "netpoll: Bonding and netpoll cannot co-exists. Test failed." >&2
> +		exit "${ksft_fail}"
> +

nit: extra nl

> +	fi
> +}

> +# Test #3
> +# Detach the interface from a bonding interface and attach netpoll again
> +delete_bond_and_reenable_target
> +echo "test #3: Able to attach to an unbound interface. Test passed." >&2

Do we need a fouth case? Enable netpoll on an interface and then try to
enslave it while netpoll is active, then try to enable netpoll on the
bond?

And possibly a couple of cases where we set up netpoll on the bond
first, then we add to bond (success and fail case).

> +cleanup_bond
> +trap - EXIT
> +exit "${EXIT_STATUS}"
> diff --git a/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh b/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
> index 9b5ef8074440c..4862d025b7c74 100644
> --- a/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
> +++ b/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
> @@ -28,17 +28,24 @@ NETCONS_PATH="${NETCONS_CONFIGFS}"/"${TARGET}"
>  # NAMESPACE will be populated by setup_ns with a random value
>  NAMESPACE=""
>  
> -# IDs for netdevsim
> +# IDs for netdevsim. We either use NSIM_DEV_{1,2}_ID for standard test
> +# or NSIM_BOND_{T,R}X_{1,2} for the bonding tests. Not both at the
> +# same time.
>  NSIM_DEV_1_ID=$((256 + RANDOM % 256))
>  NSIM_DEV_2_ID=$((512 + RANDOM % 256))
> +NSIM_BOND_TX_1=$((768 + RANDOM % 256))
> +NSIM_BOND_TX_2=$((1024 + RANDOM % 256))
> +NSIM_BOND_RX_1=$((1280 + RANDOM % 256))
> +NSIM_BOND_RX_2=$((1536 + RANDOM % 256))
>  NSIM_DEV_SYS_NEW="/sys/bus/netdevsim/new_device"
> +NSIM_DEV_SYS_LINK="/sys/bus/netdevsim/link_device"
> +NSIM_DEV_SYS_DEL="/sys/bus/netdevsim/del_device"
>  
>  # Used to create and delete namespaces
>  source "${LIBDIR}"/../../../../net/lib.sh
>  
>  # Create netdevsim interfaces
>  create_ifaces() {
> -
>  	echo "$NSIM_DEV_2_ID" > "$NSIM_DEV_SYS_NEW"
>  	echo "$NSIM_DEV_1_ID" > "$NSIM_DEV_SYS_NEW"
>  	udevadm settle 2> /dev/null || true
> @@ -54,7 +61,6 @@ create_ifaces() {
>  }
>  
>  link_ifaces() {
> -	local NSIM_DEV_SYS_LINK="/sys/bus/netdevsim/link_device"
>  	local SRCIF_IFIDX=$(cat /sys/class/net/"$SRCIF"/ifindex)
>  	local DSTIF_IFIDX=$(cat /sys/class/net/"$DSTIF"/ifindex)
>  
> @@ -96,6 +102,33 @@ function select_ipv4_or_ipv6()
>  	fi
>  }
>  
> +# Create 4 netdevsim interfaces. Two of them will be bound to TX bonding iface
> +# and the other two will be bond to the RX interface (on the other namespace)
> +function create_ifaces_bond() {
> +	echo "$NSIM_BOND_TX_1" > "$NSIM_DEV_SYS_NEW"
> +	echo "$NSIM_BOND_TX_2" > "$NSIM_DEV_SYS_NEW"
> +	echo "$NSIM_BOND_RX_1" > "$NSIM_DEV_SYS_NEW"
> +	echo "$NSIM_BOND_RX_2" > "$NSIM_DEV_SYS_NEW"
> +	udevadm settle 2> /dev/null || true
> +
> +	local BOND_TX1=/sys/bus/netdevsim/devices/netdevsim"$NSIM_BOND_TX_1"
> +	local BOND_TX2=/sys/bus/netdevsim/devices/netdevsim"$NSIM_BOND_TX_2"
> +	local BOND_RX1=/sys/bus/netdevsim/devices/netdevsim"$NSIM_BOND_RX_1"
> +	local BOND_RX2=/sys/bus/netdevsim/devices/netdevsim"$NSIM_BOND_RX_2"
> +
> +	# TX
> +	BOND_TX1_IF=$(find "$BOND_TX1"/net -maxdepth 1 -type d ! \
> +		-path "$BOND_TX1"/net -exec basename {} \; | grep -v net)
> +	BOND_TX2_IF=$(find "$BOND_TX2"/net -maxdepth 1 -type d ! \
> +		-path "$BOND_TX2"/net -exec basename {} \; | grep -v net)
> +
> +	# RX
> +	BOND_RX1_IF=$(find "$BOND_RX1"/net -maxdepth 1 -type d ! \
> +		-path "$BOND_RX1"/net -exec basename {} \; | grep -v net)
> +	BOND_RX2_IF=$(find "$BOND_RX2"/net -maxdepth 1 -type d ! \
> +		-path "$BOND_RX2"/net -exec basename {} \; | grep -v net)
> +}
> +
>  function set_network() {
>  	local IP_VERSION=${1:-"ipv4"}
>  
> @@ -180,8 +213,6 @@ function disable_release_append() {
>  }
>  
>  function do_cleanup() {
> -	local NSIM_DEV_SYS_DEL="/sys/bus/netdevsim/del_device"
> -
>  	# Delete netdevsim devices
>  	echo "$NSIM_DEV_2_ID" > "$NSIM_DEV_SYS_DEL"
>  	echo "$NSIM_DEV_1_ID" > "$NSIM_DEV_SYS_DEL"
> @@ -193,14 +224,26 @@ function do_cleanup() {
>  	echo "${DEFAULT_PRINTK_VALUES}" > /proc/sys/kernel/printk
>  }
>  
> -function cleanup() {
> +function cleanup_netcons() {
>  	# delete netconsole dynamic reconfiguration
> -	echo 0 > "${NETCONS_PATH}"/enabled
> +	# do not fail if the target is already disabled
> +	if [[ ! -d "${NETCONS_PATH}" ]]
> +	then
> +		# in some cases this is called before netcons path is created
> +		return
> +	fi
> +	if [[ $(cat "${NETCONS_PATH}"/enabled) != 0 ]]
> +	then
> +		echo 0 > "${NETCONS_PATH}"/enabled || true
> +	fi
>  	# Remove all the keys that got created during the selftest
>  	find "${NETCONS_PATH}/userdata/" -mindepth 1 -type d -delete
>  	# Remove the configfs entry
>  	rmdir "${NETCONS_PATH}"
> +}
>  
> +function cleanup() {
> +	cleanup_netcons
>  	do_cleanup
>  }
>  
> @@ -377,3 +420,105 @@ function wait_for_port() {
>  	# more frequently on IPv6
>  	sleep 1
>  }
> +
> +# netdevsim link BOND_TX to BOND_RX interfaces
> +function link_ifaces_bond() {
> +	local BOND_TX1_IFIDX
> +	local BOND_TX2_IFIDX
> +	local BOND_RX1_IFIDX
> +	local BOND_RX2_IFIDX
> +
> +	BOND_TX1_IFIDX=$(cat /sys/class/net/"$BOND_TX1_IF"/ifindex)
> +	BOND_TX2_IFIDX=$(cat /sys/class/net/"$BOND_TX2_IF"/ifindex)
> +	BOND_RX1_IFIDX=$(cat /sys/class/net/"$BOND_RX1_IF"/ifindex)
> +	BOND_RX2_IFIDX=$(cat /sys/class/net/"$BOND_RX2_IF"/ifindex)
> +
> +	exec {NAMESPACE_FD}</var/run/netns/"${NAMESPACE}"
> +	exec {INITNS_FD}</proc/self/ns/net
> +
> +	# Bind the dst interfaces to namespace
> +	ip link set "${BOND_RX1_IF}" netns "${NAMESPACE}"
> +	ip link set "${BOND_RX2_IF}" netns "${NAMESPACE}"
> +
> +	# Linking TX ifaces to the RX ones (on the other namespace}
> +	echo "${INITNS_FD}:$BOND_TX1_IFIDX $NAMESPACE_FD:$BOND_RX1_IFIDX"  \
> +		> "$NSIM_DEV_SYS_LINK"
> +	echo "${INITNS_FD}:$BOND_TX2_IFIDX $NAMESPACE_FD:$BOND_RX2_IFIDX"  \
> +		> "$NSIM_DEV_SYS_LINK"
> +}
> +
> +# Create "bond_tx_XX" and "bond_rx_XX" interfaces, and set DSTIF and SRCIF with
> +# the bonding interfaces
> +function setup_bonding_ifaces() {
> +	local RAND=$(( RANDOM % 100 ))
> +	BONDTX_IF="bond_tx_$RAND"
> +	BONDRX_IF="bond_rx_$RAND"
> +
> +	if ! ip link add "${BONDTX_IF}" type bond mode balance-rr
> +	then
> +		echo "Failed to create bond TX interface. Is CONFIG_BONDING set?" >&2
> +		# only clean nsim ifaces and namespace. Nothing else has been
> +		# initialized
> +		cleanup_bond_nsim
> +		trap - EXIT
> +		exit "${ksft_skip}"
> +	fi
> +	ip link set "${BOND_TX1_IF}" down
> +	ip link set "${BOND_TX2_IF}" down
> +
> +	ip link set "${BOND_TX1_IF}" master "${BONDTX_IF}"
> +	ip link set "${BOND_TX2_IF}" master "${BONDTX_IF}"
> +	ip link set "${BONDTX_IF}" up
> +
> +	# now create the RX bonding iface
> +	ip netns exec "${NAMESPACE}" \
> +		ip link add "${BONDRX_IF}" type bond mode balance-rr
> +	ip netns exec "${NAMESPACE}" \
> +		ip link set "${BOND_RX1_IF}" down
> +	ip netns exec "${NAMESPACE}" \
> +		ip link set "${BOND_RX2_IF}" down
> +
> +	ip netns exec "${NAMESPACE}" \
> +		ip link set "${BOND_RX1_IF}" master "${BONDRX_IF}"
> +	ip netns exec "${NAMESPACE}" \
> +		ip link set "${BOND_RX2_IF}" master "${BONDRX_IF}"
> +	ip netns exec "${NAMESPACE}" \
> +		ip link set "${BONDRX_IF}" up
> +	ip netns exec "${NAMESPACE}" \
> +		ip link set "${BOND_RX1_IF}" up
> +	ip netns exec "${NAMESPACE}" \
> +		ip link set "${BOND_RX2_IF}" up
> +
> +}
> +
> +# Clean up netdevsim ifaces created for bonding test
> +function cleanup_bond_nsim() {
> +	echo "$NSIM_BOND_TX_1" > "$NSIM_DEV_SYS_DEL"
> +	echo "$NSIM_BOND_TX_2" > "$NSIM_DEV_SYS_DEL"
> +	echo "$NSIM_BOND_RX_1" > "$NSIM_DEV_SYS_DEL"
> +	echo "$NSIM_BOND_RX_2" > "$NSIM_DEV_SYS_DEL"
> +	cleanup_all_ns
> +}
> +
> +# cleanup tests that use bonding interfaces
> +function cleanup_bond() {
> +	cleanup_netcons
> +
> +	# Delete TX ifaces
> +	ip link set "${BONDTX_IF}" down  2> /dev/null|| true
> +	ip link set "${BOND_TX1_IF}" down || true
> +	ip link set "${BOND_TX2_IF}" down || true
> +	ip link delete "${BONDTX_IF}" type bond  2> /dev/null || true
> +
> +	# Delete RX ifaces
> +	ip netns exec "${NAMESPACE}" \
> +		ip link set "${BONDRX_IF}" down || true
> +	ip netns exec "${NAMESPACE}" \
> +		ip link set "${BOND_RX1_IF}" down || true
> +	ip netns exec "${NAMESPACE}" \
> +		ip link set "${BOND_RX2_IF}" down || true
> +	ip netns exec "${NAMESPACE}" \
> +		ip link delete "${BONDRX_IF}" type bond  || true
> +
> +	cleanup_bond_nsim
> +}
> 
> 

Re: [PATCH net v5 4/4] selftest: netcons: add test for netconsole over bonded interfaces

[Breno Leitao]

On Fri, Sep 26, 2025 at 11:32:08AM -0700, Jakub Kicinski wrote:
> On Fri, 26 Sep 2025 07:06:50 -0700 Breno Leitao wrote:
> > +# Test #3
> > +# Detach the interface from a bonding interface and attach netpoll again
> > +delete_bond_and_reenable_target
> > +echo "test #3: Able to attach to an unbound interface. Test passed." >&2
> 
> Do we need a fouth case? Enable netpoll on an interface and then try to
> enslave it while netpoll is active, then try to enable netpoll on the
> bond?

Sure, but this is boring, since the interface needs to go down before
enslaving it, which will turn off netconsole/netpoll.

I've added an additional test, where I set netconsole to a
sub-interface, get it down and then enslave it. Then, enable netconsole
on the bond interface.

> And possibly a couple of cases where we set up netpoll on the bond
> first, then we add to bond (success and fail case).

Not sure if I understand this case correctly, but I've added a test
where I create a bonding interface (let's call it bond0) with one
device, then I enable netconsole in bond0. Later, I've added a second
interface to bond0, and make sure netconsole is enabled in bond0.

Is this what you meant?

Here is the current selftest with the additional tests above (and
fixes):

Author: Breno Leitao <leitao@debian.org>
Date:   Wed Sep 17 01:46:26 2025 -0700

    selftest: netcons: add test for netconsole over bonded interfaces
    
    This patch adds a selftest that verifies netconsole functionality
    over bonded network interfaces using netdevsim. It sets up two bonded
    interfaces acting as transmit (TX) and receive (RX) ends, placed in
    separate network namespaces. The test sends kernel log messages and
    verifies that they are properly received on the bonded RX interfaces
    with both IPv4 and IPv6, and using basic and extended netconsole
    formats.
    
    This patchset aims to test a long-standing netpoll are where netpoll has
    multiple users. (in this case netconsole and bonding). A similar
    selftest has been discussed in [1] and [2].
    
    This test also tries to enable bonding and netpoll in different order,
    just to guarantee that all the possibilites are exercised.
    
    Link: https://lore.kernel.org/all/20250905-netconsole_torture-v3-0-875c7febd316@debian.org/ [1]
    Link: https://lore.kernel.org/lkml/96b940137a50e5c387687bb4f57de8b0435a653f.1404857349.git.decot@googlers.com/ [2]
    Signed-off-by: Breno Leitao <leitao@debian.org>

diff --git a/tools/testing/selftests/drivers/net/bonding/Makefile b/tools/testing/selftests/drivers/net/bonding/Makefile
index 3462783ed3aca..790e6f086da49 100644
--- a/tools/testing/selftests/drivers/net/bonding/Makefile
+++ b/tools/testing/selftests/drivers/net/bonding/Makefile
@@ -8,6 +8,7 @@ TEST_PROGS := \
 	dev_addr_lists.sh \
 	mode-1-recovery-updelay.sh \
 	mode-2-recovery-updelay.sh \
+	netcons_over_bonding.sh \
 	bond_options.sh \
 	bond-eth-type-change.sh \
 	bond_macvlan_ipvlan.sh \
@@ -20,6 +21,7 @@ TEST_FILES := \
 	bond_topo_3d1c.sh
 
 TEST_INCLUDES := \
+	../lib/sh/lib_netcons.sh \
 	../../../net/forwarding/lib.sh \
 	../../../net/lib.sh
 
diff --git a/tools/testing/selftests/drivers/net/bonding/config b/tools/testing/selftests/drivers/net/bonding/config
index 832fa1caeb662..f4dd615dd33f1 100644
--- a/tools/testing/selftests/drivers/net/bonding/config
+++ b/tools/testing/selftests/drivers/net/bonding/config
@@ -1,5 +1,6 @@
 CONFIG_BONDING=y
 CONFIG_BRIDGE=y
+CONFIG_CONFIGFS_FS=y
 CONFIG_DUMMY=y
 CONFIG_IPV6=y
 CONFIG_MACVLAN=y
@@ -8,6 +9,10 @@ CONFIG_NET_ACT_GACT=y
 CONFIG_NET_CLS_FLOWER=y
 CONFIG_NET_CLS_MATCHALL=m
 CONFIG_NET_SCH_INGRESS=y
+CONFIG_NETCONSOLE=m
+CONFIG_NETCONSOLE_DYNAMIC=y
+CONFIG_NETCONSOLE_EXTENDED_LOG=y
+CONFIG_NETDEVSIM=m
 CONFIG_NLMON=y
 CONFIG_VETH=y
 CONFIG_VLAN_8021Q=m
diff --git a/tools/testing/selftests/drivers/net/bonding/netcons_over_bonding.sh b/tools/testing/selftests/drivers/net/bonding/netcons_over_bonding.sh
new file mode 100755
index 0000000000000..8dde9c29151e9
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/bonding/netcons_over_bonding.sh
@@ -0,0 +1,203 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# This test verifies netconsole functionality over a bonded network setup.
+#
+# Four interfaces are created using netdevsim; two of them are bonded to serve
+# as the netconsole's transmit interface. The remaining two interfaces are
+# similarly bonded and assigned to a separate network namespace, which acts as
+# the receive interface, where socat monitors for incoming messages.
+#
+# A netconsole message is then sent to ensure it is properly received across
+# this configuration.
+#
+# Later, try to enable netconsole on an interface that is part of a bonding
+# interface, which should fail. Also do some other basic small tests.
+#
+# The test's objective is to exercise netpoll usage when managed simultaneously
+# by multiple subsystems (netconsole and bonding).
+#
+# Author: Breno Leitao <leitao@debian.org>
+
+set -euo pipefail
+
+SCRIPTDIR=$(dirname "$(readlink -e "${BASH_SOURCE[0]}")")
+
+source "${SCRIPTDIR}"/../lib/sh/lib_netcons.sh
+
+modprobe netdevsim 2> /dev/null || true
+modprobe netconsole 2> /dev/null || true
+modprobe bonding 2> /dev/null || true
+
+# The content of kmsg will be save to the following file
+OUTPUT_FILE="/tmp/${TARGET}"
+
+# Check for basic system dependency and exit if not found
+check_for_dependencies
+# Set current loglevel to KERN_INFO(6), and default to KERN_NOTICE(5)
+echo "6 5" > /proc/sys/kernel/printk
+# Remove the namespace, interfaces and netconsole target on exit
+trap cleanup_bond EXIT
+
+FORMAT="extended"
+IP_VERSION="ipv6"
+
+function create_all_ifaces() {
+	# setup_ns function is coming from lib.sh
+	setup_ns NAMESPACE
+
+	# Create two interfaces for RX and two for TX
+	create_ifaces_bond
+	# Link netlink ifaces
+	link_ifaces_bond
+}
+
+# configure DSTIF and SRCIF IPs
+function configure_ifaces_ips() {
+	local IP_VERSION=${1:-"ipv4"}
+	select_ipv4_or_ipv6 "${IP_VERSION}"
+	configure_ip
+}
+
+function enable_netpoll_on_enslaved_iface() {
+	echo 0 > "${NETCONS_PATH}"/enabled
+
+	# At this stage, BOND_TX1_IF is enslaved to BONDTX_IF, and linked to
+	# BOND_RX1_IF inside the namespace.
+	echo "${BOND_TX1_IF}" > "${NETCONS_PATH}"/dev_name
+
+	# This should fail with the following message in dmesg:
+	# netpoll: netconsole: ethX is a slave device, aborting
+	set +e
+	echo 1 > "${NETCONS_PATH}"/enabled
+	set -e
+
+	if [[ $(cat "${NETCONS_PATH}"/enabled) -eq 1 ]]
+	then
+		echo "test failed: Bonding and netpoll cannot co-exists." >&2
+		exit "${ksft_fail}"
+	fi
+}
+
+function delete_bond_and_reenable_target() {
+	ip link delete "${BONDTX_IF}" type bond
+
+	# BOND_TX1_IF is not attached to a bond interface anymore
+	# netpoll can be plugged in there
+	echo "${BOND_TX1_IF}" > "${NETCONS_PATH}"/dev_name
+
+	# this should work, since the interface is not enslaved
+	echo 1 > "${NETCONS_PATH}"/enabled
+
+	if [[ $(cat "${NETCONS_PATH}"/enabled) -eq 0 ]]
+	then
+		echo "test failed: Unable to start netpoll on an unbond iface." >&2
+		exit "${ksft_fail}"
+	fi
+}
+
+# Send a netconsole message to the netconsole target
+function send_netcons_msg_through_bond_iface() {
+	# Listed for netconsole port inside the namespace and
+	# destination interface
+	listen_port_and_save_to "${OUTPUT_FILE}" "${IP_VERSION}" &
+	# Wait for socat to start and listen to the port.
+	wait_for_port "${NAMESPACE}" "${PORT}" "${IP_VERSION}"
+	# Send the message
+	echo "${MSG}: ${TARGET}" > /dev/kmsg
+	# Wait until socat saves the file to disk
+	busywait "${BUSYWAIT_TIMEOUT}" test -s "${OUTPUT_FILE}"
+	# Make sure the message was received in the dst part
+	# and exit
+	validate_result "${OUTPUT_FILE}" "${FORMAT}"
+	# kill socat in case it is still running
+	pkill_socat
+}
+
+# BOND_TX1_IF has netconsole enabled on it, bind it to
+# BONDTX_IF.
+# Given BONDTX_IF was deleted, recreate it first
+function enslave_netcons_enabled_iface {
+	# recreate the bonding iface, that got deleted in the previous
+	# test
+	ip link add "${BONDTX_IF}" type bond mode balance-rr
+	# sub-interface need to be down before attaching to bonding
+	ip link set "${BOND_TX1_IF}" down
+	ip link set "${BOND_TX1_IF}" master "${BONDTX_IF}"
+	ip link set "${BONDTX_IF}" up
+	# netconsole got disabled while the interface was down
+	if [[ $(cat "${NETCONS_PATH}"/enabled) -eq 1 ]]
+	then
+		echo "test failed: Device is part of a bond iface, cannot have netcons enabled" >&2
+		exit "${ksft_fail}"
+	fi
+}
+
+# Get netconsole enabled on a bonding interface and attach a second
+# sub-interface.
+function enslave_iface_to_bond {
+	# BONDTX_IF has only BOND_TX1_IF right now
+	echo "${BONDTX_IF}" > "${NETCONS_PATH}"/dev_name
+	echo 1 > "${NETCONS_PATH}"/enabled
+
+	# netcons is attached to bond0 and BOND_TX1_IF is
+	# part of BONDTX_IF. Attach BOND_TX2_IF to BONDTX_IF.
+	ip link set "${BOND_TX2_IF}" master "${BONDTX_IF}"
+	if [[ $(cat "${NETCONS_PATH}"/enabled) -eq 0 ]]
+	then
+		echo "test failed: Netconsole should be enabled on bonding interface. Failed" >&2
+		exit "${ksft_fail}"
+	fi
+}
+
+# Tests start here #
+####################
+
+# Create one namespace and two interfaces
+create_all_ifaces
+
+# then bind the interfaces with netpoll attached
+setup_bonding_ifaces
+
+# First test send a msg through bonding
+export DSTIF="${BONDRX_IF}"
+export SRCIF="${BONDTX_IF}"
+
+# Configure the ips as BOND_RX1_IF and BOND_TX1_IF
+configure_ifaces_ips "${IP_VERSION}"
+create_dynamic_target "${FORMAT}"
+set_user_data
+
+# Test #1 : Create an bonding interface and attach netpoll into
+# the bonding interface. Netconsole/netpoll should work on
+# the bonding interface.
+send_netcons_msg_through_bond_iface
+echo "test #1: netpoll on bonding interface worked. Test passed" >&2
+
+# Test #2: Attach netpoll to an enslaved interface
+# Try to attach netpoll to an enslaved interface (while still being part of a
+# bonding interface), which shouldn't be allowed
+enable_netpoll_on_enslaved_iface
+echo "test #2: netpoll correctly rejected enslaved interface (expected behavior). Test passed." >&2
+
+# Test #3: Unplug the interface from bond and enable netconsole
+# Detach the interface from a bonding interface and attach netpoll again
+delete_bond_and_reenable_target
+echo "test #3: Able to attach to an unbound interface. Test passed." >&2
+
+# Test #4: Enslave an interface that had netpoll enabled
+# Try to enslave the interface that has netpoll enabled.
+# Previous test has netconsole enabled in BOND_TX1_IF, try to enslave it
+enslave_netcons_enabled_iface
+echo "test #4: Enslaving an interface with netpoll attached. Test passed." >&2
+
+# Test #5: Enslave an interface to a bonding interface with netconsole
+# Enslave an interface to a bond interface that has netpoll attached
+# At this stage, BONDTX_IF is created and BOND_TX1_IF is part of it.
+# Netconsole is disabled
+enslave_iface_to_bond
+echo "test #5: Enslaving an interface to bond+netpoll. Test passed." >&2
+
+cleanup_bond
+trap - EXIT
+exit "${EXIT_STATUS}"
diff --git a/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh b/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
index 9b5ef8074440c..4862d025b7c74 100644
--- a/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
+++ b/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh
@@ -28,17 +28,24 @@ NETCONS_PATH="${NETCONS_CONFIGFS}"/"${TARGET}"
 # NAMESPACE will be populated by setup_ns with a random value
 NAMESPACE=""
 
-# IDs for netdevsim
+# IDs for netdevsim. We either use NSIM_DEV_{1,2}_ID for standard test
+# or NSIM_BOND_{T,R}X_{1,2} for the bonding tests. Not both at the
+# same time.
 NSIM_DEV_1_ID=$((256 + RANDOM % 256))
 NSIM_DEV_2_ID=$((512 + RANDOM % 256))
+NSIM_BOND_TX_1=$((768 + RANDOM % 256))
+NSIM_BOND_TX_2=$((1024 + RANDOM % 256))
+NSIM_BOND_RX_1=$((1280 + RANDOM % 256))
+NSIM_BOND_RX_2=$((1536 + RANDOM % 256))
 NSIM_DEV_SYS_NEW="/sys/bus/netdevsim/new_device"
+NSIM_DEV_SYS_LINK="/sys/bus/netdevsim/link_device"
+NSIM_DEV_SYS_DEL="/sys/bus/netdevsim/del_device"
 
 # Used to create and delete namespaces
 source "${LIBDIR}"/../../../../net/lib.sh
 
 # Create netdevsim interfaces
 create_ifaces() {
-
 	echo "$NSIM_DEV_2_ID" > "$NSIM_DEV_SYS_NEW"
 	echo "$NSIM_DEV_1_ID" > "$NSIM_DEV_SYS_NEW"
 	udevadm settle 2> /dev/null || true
@@ -54,7 +61,6 @@ create_ifaces() {
 }
 
 link_ifaces() {
-	local NSIM_DEV_SYS_LINK="/sys/bus/netdevsim/link_device"
 	local SRCIF_IFIDX=$(cat /sys/class/net/"$SRCIF"/ifindex)
 	local DSTIF_IFIDX=$(cat /sys/class/net/"$DSTIF"/ifindex)
 
@@ -96,6 +102,33 @@ function select_ipv4_or_ipv6()
 	fi
 }
 
+# Create 4 netdevsim interfaces. Two of them will be bound to TX bonding iface
+# and the other two will be bond to the RX interface (on the other namespace)
+function create_ifaces_bond() {
+	echo "$NSIM_BOND_TX_1" > "$NSIM_DEV_SYS_NEW"
+	echo "$NSIM_BOND_TX_2" > "$NSIM_DEV_SYS_NEW"
+	echo "$NSIM_BOND_RX_1" > "$NSIM_DEV_SYS_NEW"
+	echo "$NSIM_BOND_RX_2" > "$NSIM_DEV_SYS_NEW"
+	udevadm settle 2> /dev/null || true
+
+	local BOND_TX1=/sys/bus/netdevsim/devices/netdevsim"$NSIM_BOND_TX_1"
+	local BOND_TX2=/sys/bus/netdevsim/devices/netdevsim"$NSIM_BOND_TX_2"
+	local BOND_RX1=/sys/bus/netdevsim/devices/netdevsim"$NSIM_BOND_RX_1"
+	local BOND_RX2=/sys/bus/netdevsim/devices/netdevsim"$NSIM_BOND_RX_2"
+
+	# TX
+	BOND_TX1_IF=$(find "$BOND_TX1"/net -maxdepth 1 -type d ! \
+		-path "$BOND_TX1"/net -exec basename {} \; | grep -v net)
+	BOND_TX2_IF=$(find "$BOND_TX2"/net -maxdepth 1 -type d ! \
+		-path "$BOND_TX2"/net -exec basename {} \; | grep -v net)
+
+	# RX
+	BOND_RX1_IF=$(find "$BOND_RX1"/net -maxdepth 1 -type d ! \
+		-path "$BOND_RX1"/net -exec basename {} \; | grep -v net)
+	BOND_RX2_IF=$(find "$BOND_RX2"/net -maxdepth 1 -type d ! \
+		-path "$BOND_RX2"/net -exec basename {} \; | grep -v net)
+}
+
 function set_network() {
 	local IP_VERSION=${1:-"ipv4"}
 
@@ -180,8 +213,6 @@ function disable_release_append() {
 }
 
 function do_cleanup() {
-	local NSIM_DEV_SYS_DEL="/sys/bus/netdevsim/del_device"
-
 	# Delete netdevsim devices
 	echo "$NSIM_DEV_2_ID" > "$NSIM_DEV_SYS_DEL"
 	echo "$NSIM_DEV_1_ID" > "$NSIM_DEV_SYS_DEL"
@@ -193,14 +224,26 @@ function do_cleanup() {
 	echo "${DEFAULT_PRINTK_VALUES}" > /proc/sys/kernel/printk
 }
 
-function cleanup() {
+function cleanup_netcons() {
 	# delete netconsole dynamic reconfiguration
-	echo 0 > "${NETCONS_PATH}"/enabled
+	# do not fail if the target is already disabled
+	if [[ ! -d "${NETCONS_PATH}" ]]
+	then
+		# in some cases this is called before netcons path is created
+		return
+	fi
+	if [[ $(cat "${NETCONS_PATH}"/enabled) != 0 ]]
+	then
+		echo 0 > "${NETCONS_PATH}"/enabled || true
+	fi
 	# Remove all the keys that got created during the selftest
 	find "${NETCONS_PATH}/userdata/" -mindepth 1 -type d -delete
 	# Remove the configfs entry
 	rmdir "${NETCONS_PATH}"
+}
 
+function cleanup() {
+	cleanup_netcons
 	do_cleanup
 }
 
@@ -377,3 +420,105 @@ function wait_for_port() {
 	# more frequently on IPv6
 	sleep 1
 }
+
+# netdevsim link BOND_TX to BOND_RX interfaces
+function link_ifaces_bond() {
+	local BOND_TX1_IFIDX
+	local BOND_TX2_IFIDX
+	local BOND_RX1_IFIDX
+	local BOND_RX2_IFIDX
+
+	BOND_TX1_IFIDX=$(cat /sys/class/net/"$BOND_TX1_IF"/ifindex)
+	BOND_TX2_IFIDX=$(cat /sys/class/net/"$BOND_TX2_IF"/ifindex)
+	BOND_RX1_IFIDX=$(cat /sys/class/net/"$BOND_RX1_IF"/ifindex)
+	BOND_RX2_IFIDX=$(cat /sys/class/net/"$BOND_RX2_IF"/ifindex)
+
+	exec {NAMESPACE_FD}</var/run/netns/"${NAMESPACE}"
+	exec {INITNS_FD}</proc/self/ns/net
+
+	# Bind the dst interfaces to namespace
+	ip link set "${BOND_RX1_IF}" netns "${NAMESPACE}"
+	ip link set "${BOND_RX2_IF}" netns "${NAMESPACE}"
+
+	# Linking TX ifaces to the RX ones (on the other namespace}
+	echo "${INITNS_FD}:$BOND_TX1_IFIDX $NAMESPACE_FD:$BOND_RX1_IFIDX"  \
+		> "$NSIM_DEV_SYS_LINK"
+	echo "${INITNS_FD}:$BOND_TX2_IFIDX $NAMESPACE_FD:$BOND_RX2_IFIDX"  \
+		> "$NSIM_DEV_SYS_LINK"
+}
+
+# Create "bond_tx_XX" and "bond_rx_XX" interfaces, and set DSTIF and SRCIF with
+# the bonding interfaces
+function setup_bonding_ifaces() {
+	local RAND=$(( RANDOM % 100 ))
+	BONDTX_IF="bond_tx_$RAND"
+	BONDRX_IF="bond_rx_$RAND"
+
+	if ! ip link add "${BONDTX_IF}" type bond mode balance-rr
+	then
+		echo "Failed to create bond TX interface. Is CONFIG_BONDING set?" >&2
+		# only clean nsim ifaces and namespace. Nothing else has been
+		# initialized
+		cleanup_bond_nsim
+		trap - EXIT
+		exit "${ksft_skip}"
+	fi
+	ip link set "${BOND_TX1_IF}" down
+	ip link set "${BOND_TX2_IF}" down
+
+	ip link set "${BOND_TX1_IF}" master "${BONDTX_IF}"
+	ip link set "${BOND_TX2_IF}" master "${BONDTX_IF}"
+	ip link set "${BONDTX_IF}" up
+
+	# now create the RX bonding iface
+	ip netns exec "${NAMESPACE}" \
+		ip link add "${BONDRX_IF}" type bond mode balance-rr
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BOND_RX1_IF}" down
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BOND_RX2_IF}" down
+
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BOND_RX1_IF}" master "${BONDRX_IF}"
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BOND_RX2_IF}" master "${BONDRX_IF}"
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BONDRX_IF}" up
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BOND_RX1_IF}" up
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BOND_RX2_IF}" up
+
+}
+
+# Clean up netdevsim ifaces created for bonding test
+function cleanup_bond_nsim() {
+	echo "$NSIM_BOND_TX_1" > "$NSIM_DEV_SYS_DEL"
+	echo "$NSIM_BOND_TX_2" > "$NSIM_DEV_SYS_DEL"
+	echo "$NSIM_BOND_RX_1" > "$NSIM_DEV_SYS_DEL"
+	echo "$NSIM_BOND_RX_2" > "$NSIM_DEV_SYS_DEL"
+	cleanup_all_ns
+}
+
+# cleanup tests that use bonding interfaces
+function cleanup_bond() {
+	cleanup_netcons
+
+	# Delete TX ifaces
+	ip link set "${BONDTX_IF}" down  2> /dev/null|| true
+	ip link set "${BOND_TX1_IF}" down || true
+	ip link set "${BOND_TX2_IF}" down || true
+	ip link delete "${BONDTX_IF}" type bond  2> /dev/null || true
+
+	# Delete RX ifaces
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BONDRX_IF}" down || true
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BOND_RX1_IF}" down || true
+	ip netns exec "${NAMESPACE}" \
+		ip link set "${BOND_RX2_IF}" down || true
+	ip netns exec "${NAMESPACE}" \
+		ip link delete "${BONDRX_IF}" type bond  || true
+
+	cleanup_bond_nsim
+}

Re: [PATCH net v5 4/4] selftest: netcons: add test for netconsole over bonded interfaces

[Jakub Kicinski]

On Mon, 29 Sep 2025 07:50:17 -0700 Breno Leitao wrote:
> Not sure if I understand this case correctly, but I've added a test
> where I create a bonding interface (let's call it bond0) with one
> device, then I enable netconsole in bond0. Later, I've added a second
> interface to bond0, and make sure netconsole is enabled in bond0.
> 
> Is this what you meant?

Please post v6 to get the patch into the normal review queue.
We don't usually continue patch review in comments :)