On Tue, Mar 12, 2024 at 01:05:37PM +0800, David Gow wrote: > On Sat, 2 Mar 2024 at 03:40, Mickaël Salaün <mic@xxxxxxxxxxx> wrote: > > > > 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@xxxxxxxxxx> > > Cc: David Gow <davidgow@xxxxxxxxxx> > > Cc: Rae Moar <rmoar@xxxxxxxxxx> > > Cc: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx> > > Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> > > Signed-off-by: Mickaël Salaün <mic@xxxxxxxxxxx> > > Link: https://lore.kernel.org/r/20240301194037.532117-5-mic@xxxxxxxxxxx > > --- > > This works fine here, and looks good. > > The use of task_struct->vfork_done is a bit confusing, as there's no > documentation (that I could find) about what vfork_done means for > kthreads. From the code, it looks to just be a copy of > kthread->exited, which is much more obvious a name. Indeed > > Would it make sense to either (a) replace this with a call to > to_kthread(), and kthread->exited, or (b) add a comment explaining > what vfork_done means here. kthread_stop() itself is using > to_kthread() and kthread->exited -- even though task_struct is also > there -- so I'd feel a bit more comfortable with that option. I used vfork_done because to_kthread() and struct kthread are private. As for a vfork(2), vfork_done is useful to wait for the end of a task. Feel free to add a comment explaining vfork_done. Thanks > > Otherwise, > Reviewed-by: David Gow <davidgow@xxxxxxxxxx> > > Cheers, > -- David > > > > > Changes since v1: > > * Added Kees's Reviewed-by. > > --- > > 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 > >
