diff mbox series

[RFC,net-next,8/8] selftests: net: dsa: add a stress test for unlocked FDB operations

Message ID 20210824114049.3814660-9-vladimir.oltean@nxp.com
State New
Headers show
Series Drop rtnl_lock from DSA .port_fdb_{add,del} | expand

Commit Message

Vladimir Oltean Aug. 24, 2021, 11:40 a.m. UTC 
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 mbox series

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index 06e39d3eba93..23b65ef5f11a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12958,6 +12958,7 @@  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