Commit 3a35c130 authored by Mickaël Salaün's avatar Mickaël Salaün Committed by Shuah Khan
Browse files

kunit: Handle test faults 



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 -EINTR 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.  To make
this explicit, export kthread_exit() for KUnit tests built as module.

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: Eric W. Biederman <ebiederm@xmission.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarDavid Gow <davidgow@google.com>
Tested-by: default avatarRae Moar <rmoar@google.com>
Signed-off-by: default avatarMickaël Salaün <mic@digikod.net>
Link: https://lore.kernel.org/r/20240408074625.65017-5-mic@digikod.net


Signed-off-by: default avatarShuah Khan <skhan@linuxfoundation.org>
parent 53026ff6

include/kunit/try-catch.h

+0 −3
Original line number Diff line number Diff line
@@ -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;

kernel/kthread.c

+1 −0
Original line number Diff line number Diff line
@@ -315,6 +315,7 @@ void __noreturn kthread_exit(long result) 
	kthread->result = result;

	do_exit(0);

}

EXPORT_SYMBOL(kthread_exit);



/**

 * kthread_complete_and_exit - Exit the current kthread.

lib/kunit/try-catch.c

+12 −7
Original line number Diff line number Diff line
@@ -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 +76,12 @@ 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,

	/*

	 * As for a vfork(2), task_struct->vfork_done (pointing to the

	 * underlying kthread->exited) can be used to wait for the end of a

	 * kernel thread.

	 */

	time_remaining = wait_for_completion_timeout(task_struct->vfork_done,

						     kunit_test_timeout());

	if (time_remaining == 0) {

		try_catch->try_result = -ETIMEDOUT;
@@ -92,7 +97,7 @@ 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)