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Date: Fri, 14 Aug 2020 20:55:27 +0000
From: Uriel Guajardo <urielguajardojr@...il.com>
To: brendanhiggins@...gle.com, peterz@...radead.org, mingo@...hat.com,
will@...nel.org
Cc: linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
kunit-dev@...glegroups.com, urielguajardo@...gle.com,
alan.maguire@...cle.com
Subject: [PATCH v3] kunit: added lockdep support
From: Uriel Guajardo <urielguajardo@...gle.com>
KUnit will fail tests upon observing a lockdep failure. Because lockdep
turns itself off after its first failure, only fail the first test and
warn users to not expect any future failures from lockdep.
Similar to lib/locking-selftest [1], we check if the status of
debug_locks has changed after the execution of a test case. However, we
do not reset lockdep afterwards.
Like the locking selftests, we also fix possible preemption count
corruption from lock bugs.
Depends on kunit: support failure from dynamic analysis tools [2]
[1] https://elixir.bootlin.com/linux/v5.7.12/source/lib/locking-selftest.c#L1137
[2] https://lore.kernel.org/linux-kselftest/20200806174326.3577537-1-urielguajardojr@gmail.com/
Signed-off-by: Uriel Guajardo <urielguajardo@...gle.com>
---
v3 changes:
- Moved lockdep checking to own file [Alan]
- Fail if preemption count changes during test [Peter]
v2 changes:
- Removed lockdep_reset [Peter]
- Added warning to users about lockdep shutting off
---
include/kunit/kunit-lockdep.h | 38 +++++++++++++++++++++++++++++++++++
lib/kunit/Makefile | 2 ++
lib/kunit/kunit-lockdep.c | 37 ++++++++++++++++++++++++++++++++++
lib/kunit/test.c | 7 ++++++-
4 files changed, 83 insertions(+), 1 deletion(-)
create mode 100644 include/kunit/kunit-lockdep.h
create mode 100644 lib/kunit/kunit-lockdep.c
diff --git a/include/kunit/kunit-lockdep.h b/include/kunit/kunit-lockdep.h
new file mode 100644
index 000000000000..9cb8b931a9c6
--- /dev/null
+++ b/include/kunit/kunit-lockdep.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Lockdep integration into KUnit tests
+ *
+ * Copyright (C) 2020, Google LLC.
+ * Author: Uriel Guajardo <urielguajardo@...gle.com>
+ */
+#ifndef _KUNIT_LOCKDEP_H
+#define _KUNIT_LOCKDEP_H
+
+#include <kunit/test.h>
+
+struct kunit_lockdep {
+ int preempt_count;
+ bool debug_locks;
+};
+
+#if IS_ENABLED(CONFIG_LOCKDEP)
+
+void kunit_init_lockdep(struct kunit *test, struct kunit_lockdep *lockdep);
+
+void kunit_check_lockdep(struct kunit *test, struct kunit_lockdep *lockdep);
+
+#else
+
+static inline void kunit_init_lockdep(struct kunit *test,
+ struct kunit_lockdep *lockdep)
+{
+}
+
+static inline void kunit_check_lockdep(struct kunit *test,
+ struct kunit_lockdep *lockdep)
+{
+}
+
+#endif
+
+#endif /* _KUNIT_LOCKDEP_H */
diff --git a/lib/kunit/Makefile b/lib/kunit/Makefile
index 724b94311ca3..084806cea994 100644
--- a/lib/kunit/Makefile
+++ b/lib/kunit/Makefile
@@ -5,6 +5,8 @@ kunit-objs += test.o \
assert.o \
try-catch.o
+obj-$(CONFIG_LOCKDEP) += kunit-lockdep.o
+
ifeq ($(CONFIG_KUNIT_DEBUGFS),y)
kunit-objs += debugfs.o
endif
diff --git a/lib/kunit/kunit-lockdep.c b/lib/kunit/kunit-lockdep.c
new file mode 100644
index 000000000000..cc8c1baf25cd
--- /dev/null
+++ b/lib/kunit/kunit-lockdep.c
@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Lockdep integration into KUnit tests
+ *
+ * Copyright (C) 2020, Google LLC.
+ * Author: Uriel Guajardo <urielguajardo@...gle.com>
+ */
+
+#include <kunit/kunit-lockdep.h>
+#include <linux/debug_locks.h>
+#include <linux/sched.h>
+
+void kunit_init_lockdep(struct kunit *test, struct kunit_lockdep *lockdep) {
+ lockdep->debug_locks = debug_locks;
+ lockdep->preempt_count = preempt_count();
+}
+
+void kunit_check_lockdep(struct kunit *test, struct kunit_lockdep *lockdep) {
+ int saved_preempt_count = lockdep->preempt_count;
+ bool saved_debug_locks = lockdep->debug_locks;
+
+ if (DEBUG_LOCKS_WARN_ON(preempt_count() != saved_preempt_count))
+ preempt_count_set(saved_preempt_count);
+
+#ifdef CONFIG_TRACE_IRQFLAGS
+ if (softirq_count())
+ current->softirqs_enabled = 0;
+ else
+ current->softirqs_enabled = 1;
+#endif
+
+ if (saved_debug_locks && !debug_locks) {
+ kunit_set_failure(test);
+ kunit_warn(test, "Dynamic analysis tool failure from LOCKDEP.");
+ kunit_warn(test, "Further tests will have LOCKDEP disabled.");
+ }
+}
diff --git a/lib/kunit/test.c b/lib/kunit/test.c
index d8189d827368..7f0af0465e6f 100644
--- a/lib/kunit/test.c
+++ b/lib/kunit/test.c
@@ -7,6 +7,7 @@
*/
#include <kunit/test.h>
+#include <kunit/kunit-lockdep.h>
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/sched/debug.h>
@@ -290,6 +291,9 @@ static void kunit_try_run_case(void *data)
struct kunit_suite *suite = ctx->suite;
struct kunit_case *test_case = ctx->test_case;
+ struct kunit_lockdep lockdep;
+ kunit_init_lockdep(test, &lockdep);
+
current->kunit_test = test;
/*
@@ -298,7 +302,8 @@ static void kunit_try_run_case(void *data)
* thread will resume control and handle any necessary clean up.
*/
kunit_run_case_internal(test, suite, test_case);
- /* This line may never be reached. */
+ /* These lines may never be reached. */
+ kunit_check_lockdep(test, &lockdep);
kunit_run_case_cleanup(test, suite);
}
--
2.28.0.220.ged08abb693-goog
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