Merge branch 'net-netpoll-fix-memory-leak-and-add-comprehensive-selftests'

Breno Leitao says:

====================
net: netpoll: fix memory leak and add comprehensive selftests

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
efa95b01da ("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]
====================

Link: https://patch.msgid.link/20251107-netconsole_torture-v10-0-749227b55f63@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/core/netpoll.c

@@ -811,6 +811,10 @@ 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;
 
@@ -820,8 +824,7 @@ 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);
 }

tools/testing/selftests/drivers/net/Makefile

@@ -18,6 +18,7 @@ TEST_PROGS := \
 	netcons_fragmented_msg.sh \
 	netcons_overflow.sh \
 	netcons_sysdata.sh \
+	netcons_torture.sh \
 	netpoll_basic.py \
 	ping.py \
 	psp.py \

tools/testing/selftests/drivers/net/bonding/Makefile

@@ -14,6 +14,7 @@ TEST_PROGS := \
 	dev_addr_lists.sh \
 	mode-1-recovery-updelay.sh \
 	mode-2-recovery-updelay.sh \
+	netcons_over_bonding.sh \
 # end of TEST_PROGS
 
 TEST_FILES := \
@@ -24,6 +25,7 @@ TEST_FILES := \
 
 TEST_INCLUDES := \
 	../../../net/lib.sh \
+	../lib/sh/lib_netcons.sh \
 	../../../net/forwarding/lib.sh \
 # end of TEST_INCLUDES
 

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_INET_ESP=y
 CONFIG_INET_ESP_OFFLOAD=y
@@ -9,6 +10,9 @@ CONFIG_MACVLAN=y
 CONFIG_NET_ACT_GACT=y
 CONFIG_NET_CLS_FLOWER=y
 CONFIG_NET_CLS_MATCHALL=m
+CONFIG_NETCONSOLE=m
+CONFIG_NETCONSOLE_DYNAMIC=y
+CONFIG_NETCONSOLE_EXTENDED_LOG=y
 CONFIG_NETDEVSIM=m
 CONFIG_NET_SCH_INGRESS=y
 CONFIG_NLMON=y

tools/testing/selftests/drivers/net/bonding/netcons_over_bonding.sh

@@ -0,0 +1,361 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# This selftest exercises trying to have multiple netpoll users at the same
+# time.
+#
+# This selftest has multiple smalls test inside, and the goal is to
+# get interfaces with bonding and netconsole in different orders in order
+# to catch any possible issue.
+#
+# The main test composes of four interfaces being 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, run a few other tests, to make sure that bonding and netconsole
+# cannot coexist.
+#
+# 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
+modprobe veth 2> /dev/null || true
+
+# The content of kmsg will be save to the following file
+OUTPUT_FILE="/tmp/${TARGET}"
+
+# Check for basic system dependency and exit if not found
+check_for_dependencies
+# Set current loglevel to KERN_INFO(6), and default to KERN_NOTICE(5)
+echo "6 5" > /proc/sys/kernel/printk
+# Remove the namespace, interfaces and netconsole target on exit
+trap cleanup_bond EXIT
+
+FORMAT="extended"
+IP_VERSION="ipv4"
+VETH0="veth"$(( RANDOM % 256))
+VETH1="veth"$((256 +  RANDOM % 256))
+TXNS=""
+RXNS=""
+
+# Create "bond_tx_XX" and "bond_rx_XX" interfaces, and set DSTIF and SRCIF with
+# the bonding interfaces
+function setup_bonding_ifaces() {
+	local RAND=$(( RANDOM % 100 ))
+	BOND_TX_MAIN_IF="bond_tx_$RAND"
+	BOND_RX_MAIN_IF="bond_rx_$RAND"
+
+	# Setup TX
+	if ! ip -n "${TXNS}" link add "${BOND_TX_MAIN_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 "${ksft_skip}"
+	fi
+
+	# create_netdevsim() got the interface up, but it needs to be down
+	# before being enslaved.
+	ip -n "${TXNS}" \
+		link set "${BOND_TX1_SLAVE_IF}" down
+	ip -n "${TXNS}" \
+		link set "${BOND_TX2_SLAVE_IF}" down
+	ip -n "${TXNS}" \
+		link set "${BOND_TX1_SLAVE_IF}" master "${BOND_TX_MAIN_IF}"
+	ip -n "${TXNS}" \
+		link set "${BOND_TX2_SLAVE_IF}" master "${BOND_TX_MAIN_IF}"
+	ip -n "${TXNS}" \
+		link set "${BOND_TX_MAIN_IF}" up
+
+	# Setup RX
+	ip -n "${RXNS}" \
+		link add "${BOND_RX_MAIN_IF}" type bond mode balance-rr
+	ip -n "${RXNS}" \
+		link set "${BOND_RX1_SLAVE_IF}" down
+	ip -n "${RXNS}" \
+		link set "${BOND_RX2_SLAVE_IF}" down
+	ip -n "${RXNS}" \
+		link set "${BOND_RX1_SLAVE_IF}" master "${BOND_RX_MAIN_IF}"
+	ip -n "${RXNS}" \
+		link set "${BOND_RX2_SLAVE_IF}" master "${BOND_RX_MAIN_IF}"
+	ip -n "${RXNS}" \
+		link set "${BOND_RX_MAIN_IF}" up
+
+	export DSTIF="${BOND_RX_MAIN_IF}"
+	export SRCIF="${BOND_TX_MAIN_IF}"
+}
+
+# Create 4 netdevsim interfaces. Two of them will be bound to TX bonding iface
+# and the other two will be bond to the RX interface (on the other namespace)
+function create_ifaces_bond() {
+	BOND_TX1_SLAVE_IF=$(create_netdevsim "${NSIM_BOND_TX_1}" "${TXNS}")
+	BOND_TX2_SLAVE_IF=$(create_netdevsim "${NSIM_BOND_TX_2}" "${TXNS}")
+	BOND_RX1_SLAVE_IF=$(create_netdevsim "${NSIM_BOND_RX_1}" "${RXNS}")
+	BOND_RX2_SLAVE_IF=$(create_netdevsim "${NSIM_BOND_RX_2}" "${RXNS}")
+}
+
+# netdevsim link BOND_TX to BOND_RX interfaces
+function link_ifaces_bond() {
+	local BOND_TX1_SLAVE_IFIDX
+	local BOND_TX2_SLAVE_IFIDX
+	local BOND_RX1_SLAVE_IFIDX
+	local BOND_RX2_SLAVE_IFIDX
+	local TXNS_FD
+	local RXNS_FD
+
+	BOND_TX1_SLAVE_IFIDX=$(ip netns exec "${TXNS}" \
+				cat /sys/class/net/"$BOND_TX1_SLAVE_IF"/ifindex)
+	BOND_TX2_SLAVE_IFIDX=$(ip netns exec "${TXNS}" \
+				cat /sys/class/net/"$BOND_TX2_SLAVE_IF"/ifindex)
+	BOND_RX1_SLAVE_IFIDX=$(ip netns exec "${RXNS}" \
+				cat /sys/class/net/"$BOND_RX1_SLAVE_IF"/ifindex)
+	BOND_RX2_SLAVE_IFIDX=$(ip netns exec "${RXNS}" \
+				cat /sys/class/net/"$BOND_RX2_SLAVE_IF"/ifindex)
+
+	exec {TXNS_FD}</var/run/netns/"${TXNS}"
+	exec {RXNS_FD}</var/run/netns/"${RXNS}"
+
+	# Linking TX ifaces to the RX ones (on the other namespace)
+	echo "${TXNS_FD}:$BOND_TX1_SLAVE_IFIDX $RXNS_FD:$BOND_RX1_SLAVE_IFIDX"  \
+		> "$NSIM_DEV_SYS_LINK"
+	echo "${TXNS_FD}:$BOND_TX2_SLAVE_IFIDX $RXNS_FD:$BOND_RX2_SLAVE_IFIDX"  \
+		> "$NSIM_DEV_SYS_LINK"
+
+	exec {TXNS_FD}<&-
+	exec {RXNS_FD}<&-
+}
+
+function create_all_ifaces() {
+	# setup_ns function is coming from lib.sh
+	setup_ns TXNS RXNS
+	export NAMESPACE="${RXNS}"
+
+	# 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}"
+
+	ip -n "${RXNS}" addr add "${DSTIP}"/24 dev "${DSTIF}"
+	ip -n "${RXNS}" link set "${DSTIF}" up
+
+	ip -n "${TXNS}" addr add "${SRCIP}"/24 dev "${SRCIF}"
+	ip -n "${TXNS}" link set "${SRCIF}" up
+}
+
+function test_enable_netpoll_on_enslaved_iface() {
+	echo 0 > "${NETCONS_PATH}"/enabled
+
+	# At this stage, BOND_TX1_SLAVE_IF is enslaved to BOND_TX_MAIN_IF, and
+	# linked to BOND_RX1_SLAVE_IF inside the namespace.
+	echo "${BOND_TX1_SLAVE_IF}" > "${NETCONS_PATH}"/dev_name
+
+	# This should fail with the following message in dmesg:
+	# netpoll: netconsole: ethX is a slave device, aborting
+	set +e
+	enable_netcons_ns 2> /dev/null
+	set -e
+
+	if [[ $(cat "${NETCONS_PATH}"/enabled) -eq 1 ]]
+	then
+		echo "test failed: Bonding and netpoll cannot co-exists." >&2
+		exit "${ksft_fail}"
+	fi
+}
+
+function test_delete_bond_and_reenable_target() {
+	ip -n "${TXNS}" \
+		link delete "${BOND_TX_MAIN_IF}" type bond
+
+	# BOND_TX1_SLAVE_IF is not attached to a bond interface anymore
+	# netpoll can be plugged in there
+	echo "${BOND_TX1_SLAVE_IF}" > "${NETCONS_PATH}"/dev_name
+
+	# this should work, since the interface is not enslaved
+	enable_netcons_ns
+
+	if [[ $(cat "${NETCONS_PATH}"/enabled) -eq 0 ]]
+	then
+		echo "test failed: Unable to start netpoll on an unbond iface." >&2
+		exit "${ksft_fail}"
+	fi
+}
+
+# Send a netconsole message to the netconsole target
+function test_send_netcons_msg_through_bond_iface() {
+	# Listen for netconsole port inside the namespace and
+	# destination interface
+	listen_port_and_save_to "${OUTPUT_FILE}" "${IP_VERSION}" &
+	# Wait for socat to start and listen to the port.
+	wait_for_port "${RXNS}" "${PORT}" "${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_SLAVE_IF has netconsole enabled on it, bind it to BOND_TX_MAIN_IF.
+# Given BOND_TX_MAIN_IF was deleted, recreate it first
+function test_enslave_netcons_enabled_iface {
+	# netconsole got disabled while the interface was down
+	if [[ $(cat "${NETCONS_PATH}"/enabled) -eq 0 ]]
+	then
+		echo "test failed: netconsole expected to be enabled against BOND_TX1_SLAVE_IF" >&2
+		exit "${ksft_fail}"
+	fi
+
+	# recreate the bonding iface. it got deleted by previous
+	# test (test_delete_bond_and_reenable_target)
+	ip -n "${TXNS}" \
+		link add "${BOND_TX_MAIN_IF}" type bond mode balance-rr
+
+	# sub-interface need to be down before attaching to bonding
+	# This will also disable netconsole.
+	ip -n "${TXNS}" \
+		link set "${BOND_TX1_SLAVE_IF}" down
+	ip -n "${TXNS}" \
+		link set "${BOND_TX1_SLAVE_IF}" master "${BOND_TX_MAIN_IF}"
+	ip -n "${TXNS}" \
+		link set "${BOND_TX_MAIN_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 "${ksft_fail}"
+	fi
+}
+
+# Get netconsole enabled on a bonding interface and attach a second
+# sub-interface.
+function test_enslave_iface_to_bond {
+	# BOND_TX_MAIN_IF has only BOND_TX1_SLAVE_IF right now
+	echo "${BOND_TX_MAIN_IF}" > "${NETCONS_PATH}"/dev_name
+	enable_netcons_ns
+
+	# netcons is attached to bond0 and BOND_TX1_SLAVE_IF is
+	# part of BOND_TX_MAIN_IF. Attach BOND_TX2_SLAVE_IF to BOND_TX_MAIN_IF.
+	ip -n "${TXNS}" \
+		link set "${BOND_TX2_SLAVE_IF}" master "${BOND_TX_MAIN_IF}"
+	if [[ $(cat "${NETCONS_PATH}"/enabled) -eq 0 ]]
+	then
+		echo "test failed: Netconsole should be enabled on bonding interface. Failed" >&2
+		exit "${ksft_fail}"
+	fi
+}
+
+function test_enslave_iff_disabled_netpoll_iface {
+	local ret
+
+	# Create two interfaces. veth interfaces it known to have
+	# IFF_DISABLE_NETPOLL set
+	if ! ip link add "${VETH0}" type veth peer name "${VETH1}"
+	then
+		echo "Failed to create veth TX interface. Is CONFIG_VETH set?" >&2
+		exit "${ksft_skip}"
+	fi
+	set +e
+	# This will print RTNETLINK answers: Device or resource busy
+	ip link set "${VETH0}" master "${BOND_TX_MAIN_IF}" 2> /dev/null
+	ret=$?
+	set -e
+	if [[ $ret -eq 0 ]]
+	then
+		echo "test failed: veth interface could not be enslaved"
+		exit "${ksft_fail}"
+	fi
+}
+
+# Given that netconsole picks the current net namespace, we need to enable it
+# from inside the TXNS namespace
+function enable_netcons_ns() {
+	ip netns exec "${TXNS}" sh -c \
+		"mount -t configfs configfs /sys/kernel/config && echo 1 > $NETCONS_PATH/enabled"
+}
+
+####################
+# Tests start here #
+####################
+
+# Create regular interfaces using netdevsim and link them
+create_all_ifaces
+
+# Setup the bonding interfaces
+# BOND_RX_MAIN_IF has BOND_RX{1,2}_SLAVE_IF
+# BOND_TX_MAIN_IF has BOND_TX{1,2}_SLAVE_IF
+setup_bonding_ifaces
+
+# Configure the ips as BOND_RX1_SLAVE_IF and BOND_TX1_SLAVE_IF
+configure_ifaces_ips "${IP_VERSION}"
+
+_create_dynamic_target "${FORMAT}" "${NETCONS_PATH}"
+enable_netcons_ns
+set_user_data
+
+# Test #1 : Create an bonding interface and attach netpoll into
+# the bonding interface. Netconsole/netpoll should work on
+# the bonding interface.
+test_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 sub-interface (while still being part of
+# a bonding interface), which shouldn't be allowed
+test_enable_netpoll_on_enslaved_iface
+echo "test #2: netpoll correctly rejected enslaved interface (expected behavior). Test passed." >&2
+
+# Test #3: Unplug the sub-interface from bond and enable netconsole
+# Detach the interface from a bonding interface and attach netpoll again
+test_delete_bond_and_reenable_target
+echo "test #3: Able to attach to an unbound interface. Test passed." >&2
+
+# Test #4: Enslave a sub-interface that had netconsole enabled
+# Try to enslave an interface that has netconsole/netpoll enabled.
+# Previous test has netconsole enabled in BOND_TX1_SLAVE_IF, try to enslave it
+test_enslave_netcons_enabled_iface
+echo "test #4: Enslaving an interface with netpoll attached. Test passed." >&2
+
+# Test #5: Enslave a sub-interface to a bonding interface
+# Enslave an interface to a bond interface that has netpoll attached
+# At this stage, BOND_TX_MAIN_IF is created and BOND_TX1_SLAVE_IF is part of
+# it. Netconsole is currently disabled
+test_enslave_iface_to_bond
+echo "test #5: Enslaving an interface to bond+netpoll. Test passed." >&2
+
+# Test #6: Enslave a IFF_DISABLE_NETPOLL sub-interface to a bonding interface
+# At this stage, BOND_TX_MAIN_IF has both sub interface and netconsole is
+# enabled. This test will try to enslave an a veth (IFF_DISABLE_NETPOLL) interface
+# and it should fail, with netpoll: veth0 doesn't support polling
+test_enslave_iff_disabled_netpoll_iface
+echo "test #6: Enslaving IFF_DISABLE_NETPOLL ifaces to bond iface is not supported. Test passed." >&2
+
+cleanup_bond
+trap - EXIT
+exit "${EXIT_STATUS}"

tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh

@@ -11,9 +11,11 @@ set -euo pipefail
 LIBDIR=$(dirname "$(readlink -e "${BASH_SOURCE[0]}")")
 
 SRCIF="" # to be populated later
+SRCIP="" # to be populated later
 SRCIP4="192.0.2.1"
 SRCIP6="fc00::1"
 DSTIF="" # to be populated later
+DSTIP="" # to be populated later
 DSTIP4="192.0.2.2"
 DSTIP6="fc00::2"
 
@@ -28,17 +30,23 @@ 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"
 
 # 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
@@ -113,31 +121,38 @@ function set_network() {
 	configure_ip
 }
 
-function create_dynamic_target() {
+function _create_dynamic_target() {
-	local FORMAT=${1:-"extended"}
+	local FORMAT="${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 "${DSTIP}" > "${NCPATH}"/remote_ip
-	echo "${SRCIP}" > "${NETCONS_PATH}"/local_ip
+	echo "${SRCIP}" > "${NCPATH}"/local_ip
-	echo "${DSTMAC}" > "${NETCONS_PATH}"/remote_mac
+	echo "${DSTMAC}" > "${NCPATH}"/remote_mac
-	echo "${SRCIF}" > "${NETCONS_PATH}"/dev_name
+	echo "${SRCIF}" > "${NCPATH}"/dev_name
 
 	if [ "${FORMAT}" == "basic" ]
 	then
 		# Basic target does not support release
-		echo 0 > "${NETCONS_PATH}"/release
+		echo 0 > "${NCPATH}"/release
-		echo 0 > "${NETCONS_PATH}"/extended
+		echo 0 > "${NCPATH}"/extended
 	elif [ "${FORMAT}" == "extended" ]
 	then
-		echo 1 > "${NETCONS_PATH}"/extended
+		echo 1 > "${NCPATH}"/extended
 	fi
+}
 
-	echo 1 > "${NETCONS_PATH}"/enabled
+function create_dynamic_target() {
+	local FORMAT=${1:-"extended"}
+	local NCPATH=${2:-"$NETCONS_PATH"}
+	_create_dynamic_target "${FORMAT}" "${NCPATH}"
+
+	echo 1 > "${NCPATH}"/enabled
 
 	# This will make sure that the kernel was able to
 	# load the netconsole driver configuration. The console message
@@ -185,14 +200,26 @@ 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
 }
 
@@ -369,3 +396,24 @@ function wait_for_port() {
 	# more frequently on IPv6
 	sleep 1
 }
+
+# Clean up netdevsim ifaces created for bonding test
+function cleanup_bond_nsim() {
+	ip -n "${TXNS}" \
+		link delete "${BOND_TX_MAIN_IF}" type bond || true
+	ip -n "${RXNS}" \
+		link delete "${BOND_RX_MAIN_IF}" type bond || true
+
+	cleanup_netdevsim "$NSIM_BOND_TX_1"
+	cleanup_netdevsim "$NSIM_BOND_TX_2"
+	cleanup_netdevsim "$NSIM_BOND_RX_1"
+	cleanup_netdevsim "$NSIM_BOND_RX_2"
+}
+
+# cleanup tests that use bonding interfaces
+function cleanup_bond() {
+	cleanup_netcons
+	cleanup_bond_nsim
+	cleanup_all_ns
+	ip link delete "${VETH0}" || true
+}

tools/testing/selftests/drivers/net/netcons_torture.sh

@@ -0,0 +1,130 @@
+#!/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=${1:-150}
+
+# Only test extended format
+FORMAT="extended"
+# And ipv6 only
+IP_VERSION="ipv6"
+
+# Create, enable and delete some targets.
+create_and_delete_random_target() {
+	COUNT=2
+	RND_PREFIX=$(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}"
+		if [[ $(cat "${RND_TARGET_PATH}/enabled") -eq 1 ]]
+		then
+			echo 0 > "${RND_TARGET_PATH}"/enabled
+		fi
+		rmdir "${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}"