[PATCH v2 net-next 9/9] selftests: net: dsa: add a stress test for unlocked FDB operations
From: Vladimir Oltean <vladimir.oltean@nxp.com>
Date: 2021-10-22 14:18:25
Subsystem:
kernel selftest framework, networking drivers, networking [dsa], the rest · Maintainers:
Shuah Khan, Shuah Khan, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Andrew Lunn, Vladimir Oltean, Linus Torvalds
This test is a bit strange in that it is perhaps more manual than others: it does not transmit a clear OK/FAIL verdict, because user space does not have synchronous feedback from the kernel. If a hardware access fails, it is in deferred context. Nonetheless, on sja1105 I have used it successfully to find and solve a concurrency issue, so it can be used as a starting point for other driver maintainers too. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> --- MAINTAINERS | 1 + .../drivers/net/dsa/test_bridge_fdb_stress.sh | 48 +++++++++++++++++++ 2 files changed, 49 insertions(+) create mode 100755 tools/testing/selftests/drivers/net/dsa/test_bridge_fdb_stress.sh
diff --git a/MAINTAINERS b/MAINTAINERS
index 20ea3338404f..997bdbf615f4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS@@ -13054,6 +13054,7 @@ F: include/linux/dsa/ F: include/linux/platform_data/dsa.h F: include/net/dsa.h F: net/dsa/ +F: tools/testing/selftests/drivers/net/dsa/ NETWORKING [GENERAL] M: "David S. Miller" <davem@davemloft.net>
diff --git a/tools/testing/selftests/drivers/net/dsa/test_bridge_fdb_stress.sh b/tools/testing/selftests/drivers/net/dsa/test_bridge_fdb_stress.sh
new file mode 100755
index 000000000000..cdb7f9ca2251
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/dsa/test_bridge_fdb_stress.sh@@ -0,0 +1,48 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 + +# Bridge FDB entries can be offloaded to DSA switches without holding the +# rtnl_mutex. Traditionally this mutex has conferred drivers implicit +# serialization, which means their code paths are not well tested in the +# presence of concurrency. +# This test creates a background task that stresses the FDB by adding and +# deleting an entry many times in a row without the rtnl_mutex held. +# It then tests the driver resistance to concurrency by calling .ndo_fdb_dump +# (with rtnl_mutex held) from a foreground task. +# Since either the FDB dump or the additions/removals can fail, but the +# additions and removals are performed in deferred as opposed to process +# context, we cannot simply check for user space error codes. + +WAIT_TIME=1 +NUM_NETIFS=1 +REQUIRE_JQ="no" +REQUIRE_MZ="no" +NETIF_CREATE="no" +lib_dir=$(dirname $0)/../../../net/forwarding +source $lib_dir/lib.sh + +cleanup() { + echo "Cleaning up" + ip link del br0 + kill $pid + killall bash + echo "Please check kernel log for errors" +} +trap 'cleanup' EXIT + +eth=${NETIFS[p1]} + +ip link del br0 2&>1 >/dev/null || : +ip link add br0 type bridge && ip link set $eth master br0 + +(while :; do + bridge fdb add 00:01:02:03:04:05 dev $eth master static + bridge fdb del 00:01:02:03:04:05 dev $eth master static +done) & +pid=$! + +for i in $(seq 1 50); do + bridge fdb show > /dev/null + sleep 3 + echo "$((${i} * 2))% complete..." +done
--
2.25.1