diff mbox series

[v4,net-next,9/9] selftests: net: dsa: add a stress test for unlocked FDB operations

Message ID 20211022184312.2454746-10-vladimir.oltean@nxp.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series Drop rtnl_lock from DSA .port_fdb_{add,del} | expand

Checks

Context Check Description
netdev/cover_letter success Series has a cover letter
netdev/fixes_present success Fixes tag not required for -next series
netdev/patch_count success Link
netdev/tree_selection success Clearly marked for net-next
netdev/subject_prefix success Link
netdev/cc_maintainers warning 5 maintainers not CCed: linux-kselftest@vger.kernel.org linux-mediatek@lists.infradead.org matthias.bgg@gmail.com shuah@kernel.org linux-arm-kernel@lists.infradead.org
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success No Fixes tag
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 54 lines checked
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/header_inline success No static functions without inline keyword in header files

Commit Message

Vladimir Oltean Oct. 22, 2021, 6:43 p.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>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
---
v3->v4:
- use "wait $pid" instead of "killall bash" :-/
- reorder "ip link del br0" and waiting for the background task on cleanup

 MAINTAINERS                                   |  1 +
 .../drivers/net/dsa/test_bridge_fdb_stress.sh | 47 +++++++++++++++++++
 2 files changed, 48 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 c5aa142d4b3a..975086c5345d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -13056,6 +13056,7 @@  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..dca8be6092b9
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/dsa/test_bridge_fdb_stress.sh
@@ -0,0 +1,47 @@ 
+#!/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"
+	kill $pid && wait $pid &> /dev/null
+	ip link del br0
+	echo "Please check kernel log for errors"
+}
+trap 'cleanup' EXIT
+
+eth=${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