From: Uriel Guajardo urielguajardo@google.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-urielguajar...

Signed-off-by: Uriel Guajardo urielguajardo@google.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@google.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@google.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); }