6.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Mickaël Salaün mic@digikod.net
[ Upstream commit 3a35c13007dea132a65f07de05c26b87837fadc2 ]
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: Kees Cook keescook@chromium.org Reviewed-by: David Gow davidgow@google.com Tested-by: Rae Moar rmoar@google.com Signed-off-by: Mickaël Salaün mic@digikod.net Link: https://lore.kernel.org/r/20240408074625.65017-5-mic@digikod.net Signed-off-by: Shuah Khan skhan@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- include/kunit/try-catch.h | 3 --- kernel/kthread.c | 1 + lib/kunit/try-catch.c | 19 ++++++++++++------- 3 files changed, 13 insertions(+), 10 deletions(-)
diff --git a/include/kunit/try-catch.h b/include/kunit/try-catch.h index c507dd43119d5..7c966a1adbd30 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/kernel/kthread.c b/kernel/kthread.c index c5e40830c1f2d..f7be976ff88af 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -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. diff --git a/lib/kunit/try-catch.c b/lib/kunit/try-catch.c index 9c9e4dcf06d96..34d30a6f23054 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"); @@ -74,8 +75,12 @@ 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; @@ -91,7 +96,7 @@ 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)