[PATCH v1 5/8] kunit: Handle test faults

Mickaël Salaün
2024-02-29T17:04:36Z

Previously, when a kernel test thread crashed (e.g. NULL pointer
dereference, general protection fault), the KUnit test hanged for 30
seconds and exited with a timeout error.

Fix this issue by waiting on task_struct->vfork_done instead of the
custom kunit_try_catch.try_completion, and track the execution state by
initially setting try_result with -EFAULT and only setting it to 0 if
the test passed.

Fix kunit_generic_run_threadfn_adapter() signature by returning 0
instead of calling kthread_complete_and_exit(). Because thread's exit
code is never checked, always set it to 0 to make it clear.

Fix the -EINTR error message, which couldn't be reached until now.

This is tested with a following patch.

Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Gow <davidgow@google.com>
Cc: Rae Moar <rmoar@google.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---
include/kunit/try-catch.h | 3 ---
lib/kunit/try-catch.c | 14 +++++++-------
2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/include/kunit/try-catch.h b/include/kunit/try-catch.h
index c507dd43119d..7c966a1adbd3 100644
--- a/include/kunit/try-catch.h
+++ b/include/kunit/try-catch.h
@@ -14,13 +14,11 @@

typedef void (*kunit_try_catch_func_t)(void *);

-struct completion;
struct kunit;

/**
* struct kunit_try_catch - provides a generic way to run code which might fail.
* @test: The test case that is currently being executed.
- * @try_completion: Completion that the control thread waits on while test runs.
* @try_result: Contains any errno obtained while running test case.
* @try: The function, the test case, to attempt to run.
* @catch: The function called if @try bails out.
@@ -46,7 +44,6 @@ struct kunit;
struct kunit_try_catch {
/* private: internal use only. */
struct kunit *test;
- struct completion *try_completion;
int try_result;
kunit_try_catch_func_t try;
kunit_try_catch_func_t catch;
diff --git a/lib/kunit/try-catch.c b/lib/kunit/try-catch.c
index cab8b24b5d5a..c6ee4db0b3bd 100644
--- a/lib/kunit/try-catch.c
+++ b/lib/kunit/try-catch.c
@@ -18,7 +18,7 @@
void __noreturn kunit_try_catch_throw(struct kunit_try_catch *try_catch)
{
try_catch->try_result = -EFAULT;
- kthread_complete_and_exit(try_catch->try_completion, -EFAULT);
+ kthread_exit(0);
}
EXPORT_SYMBOL_GPL(kunit_try_catch_throw);

@@ -26,9 +26,12 @@ static int kunit_generic_run_threadfn_adapter(void *data)
{
struct kunit_try_catch *try_catch = data;

+ try_catch->try_result = -EINTR;
try_catch->try(try_catch->context);
+ if (try_catch->try_result == -EINTR)
+ try_catch->try_result = 0;

- kthread_complete_and_exit(try_catch->try_completion, 0);
+ return 0;
}

static unsigned long kunit_test_timeout(void)
@@ -58,13 +61,11 @@ static unsigned long kunit_test_timeout(void)

void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
{
- DECLARE_COMPLETION_ONSTACK(try_completion);
struct kunit *test = try_catch->test;
struct task_struct *task_struct;
int exit_code, time_remaining;

try_catch->context = context;
- try_catch->try_completion = &try_completion;
try_catch->try_result = 0;
task_struct = kthread_create(kunit_generic_run_threadfn_adapter,
try_catch, "kunit_try_catch_thread");
@@ -75,8 +76,7 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
}
get_task_struct(task_struct);
wake_up_process(task_struct);
-
- time_remaining = wait_for_completion_timeout(&try_completion,
+ time_remaining = wait_for_completion_timeout(task_struct->vfork_done,
kunit_test_timeout());
if (time_remaining == 0) {
try_catch->try_result = -ETIMEDOUT;
@@ -92,7 +92,7 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
if (exit_code == -EFAULT)
try_catch->try_result = 0;
else if (exit_code == -EINTR)
- kunit_err(test, "wake_up_process() was never called\n");
+ kunit_err(test, "try faulted\n");
else if (exit_code == -ETIMEDOUT)
kunit_err(test, "try timed out\n");
else if (exit_code)
--
2.44.0