linux-kernel - [PATCH 06/14] net: kunit: Suppress lock warning noise at end of dev_addr

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Date: Tue, 12 Mar 2024 10:03:01 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: linux-kselftest@...r.kernel.org
Cc: David Airlie <airlied@...il.com>,
	Arnd Bergmann <arnd@...db.de>,
	Maíra Canal <mcanal@...lia.com>,
	Dan Carpenter <dan.carpenter@...aro.org>,
	Kees Cook <keescook@...omium.org>,
	Daniel Diaz <daniel.diaz@...aro.org>,
	David Gow <davidgow@...gle.com>,
	Arthur Grillo <arthurgrillo@...eup.net>,
	Brendan Higgins <brendan.higgins@...ux.dev>,
	Naresh Kamboju <naresh.kamboju@...aro.org>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Maxime Ripard <mripard@...nel.org>,
	Ville Syrjälä <ville.syrjala@...ux.intel.com>,
	Daniel Vetter <daniel@...ll.ch>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	dri-devel@...ts.freedesktop.org,
	kunit-dev@...glegroups.com,
	linux-arch@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-parisc@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org,
	linux-riscv@...ts.infradead.org,
	linux-s390@...r.kernel.org,
	linux-sh@...r.kernel.org,
	loongarch@...ts.linux.dev,
	netdev@...ts.linux.dev,
	Guenter Roeck <linux@...ck-us.net>,
	Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH 06/14] net: kunit: Suppress lock warning noise at end of dev_addr_lists tests

dev_addr_lists_test generates lock warning noise at the end of tests
if lock debugging is enabled. There are two sets of warnings.

WARNING: CPU: 0 PID: 689 at kernel/locking/mutex.c:923 __mutex_unlock_slowpath.constprop.0+0x13c/0x368
DEBUG_LOCKS_WARN_ON(__owner_task(owner) != __get_current())

WARNING: kunit_try_catch/1336 still has locks held!

KUnit test cleanup is not guaranteed to run in the same thread as the test
itself. For this test, this means that rtnl_lock() and rtnl_unlock() may
be called from different threads. This triggers the warnings.
Suppress the warnings because they are irrelevant for the test and just
confusing.

The first warning can be suppressed by using START_SUPPRESSED_WARNING()
and END_SUPPRESSED_WARNING() around the call to rtnl_unlock(). To suppress
the second warning, it is necessary to set debug_locks_silent while the
rtnl lock is held.

Cc: David Gow <davidgow@...gle.com>
Cc: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
 net/core/dev_addr_lists_test.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/core/dev_addr_lists_test.c b/net/core/dev_addr_lists_test.c
index 4dbd0dc6aea2..b427dd1a3c93 100644
--- a/net/core/dev_addr_lists_test.c
+++ b/net/core/dev_addr_lists_test.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include <kunit/test.h>
+#include <linux/debug_locks.h>
 #include <linux/etherdevice.h>
 #include <linux/netdevice.h>
 #include <linux/rtnetlink.h>
@@ -49,6 +50,7 @@ static int dev_addr_test_init(struct kunit *test)
 		KUNIT_FAIL(test, "Can't register netdev %d", err);
 	}
 
+	debug_locks_silent = 1;
 	rtnl_lock();
 	return 0;
 }
@@ -56,8 +58,12 @@ static int dev_addr_test_init(struct kunit *test)
 static void dev_addr_test_exit(struct kunit *test)
 {
 	struct net_device *netdev = test->priv;
+	DEFINE_SUPPRESSED_WARNING(__mutex_unlock_slowpath);
 
+	START_SUPPRESSED_WARNING(__mutex_unlock_slowpath);
 	rtnl_unlock();
+	END_SUPPRESSED_WARNING(__mutex_unlock_slowpath);
+	debug_locks_silent = 0;
 	unregister_netdev(netdev);
 	free_netdev(netdev);
 }
-- 
2.39.2