From 1eb69ded805103ce3ddc8b1a207abd8c24ca9e63 Mon Sep 17 00:00:00 2001 From: David Gow Date: Fri, 12 Apr 2024 10:59:01 +0800 Subject: kunit: Fix race condition in try-catch completion MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit KUnit's try-catch infrastructure now uses vfork_done, which is always set to a valid completion when a kthread is created, but which is set to NULL once the thread terminates. This creates a race condition, where the kthread exits before we can wait on it. Keep a copy of vfork_done, which is taken before we wake_up_process() and so valid, and wait on that instead. Fixes: 93533996100c ("kunit: Handle test faults") Reported-by: Linux Kernel Functional Testing Closes: https://lore.kernel.org/lkml/20240410102710.35911-1-naresh.kamboju@linaro.org/ Tested-by: Linux Kernel Functional Testing Acked-by: Mickaël Salaün Signed-off-by: David Gow Reviewed-by: Rae Moar Tested-by: Miguel Ojeda Signed-off-by: Shuah Khan --- lib/kunit/try-catch.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'lib') diff --git a/lib/kunit/try-catch.c b/lib/kunit/try-catch.c index fa687278ccc9..6bbe0025b079 100644 --- a/lib/kunit/try-catch.c +++ b/lib/kunit/try-catch.c @@ -63,6 +63,7 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context) { struct kunit *test = try_catch->test; struct task_struct *task_struct; + struct completion *task_done; int exit_code, time_remaining; try_catch->context = context; @@ -75,13 +76,16 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context) return; } get_task_struct(task_struct); - wake_up_process(task_struct); /* * 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. + * kernel thread. It is set to NULL when the thread exits, so we + * keep a copy here. */ - time_remaining = wait_for_completion_timeout(task_struct->vfork_done, + task_done = task_struct->vfork_done; + wake_up_process(task_struct); + + time_remaining = wait_for_completion_timeout(task_done, kunit_test_timeout()); if (time_remaining == 0) { try_catch->try_result = -ETIMEDOUT; -- cgit v1.2.3