On Thu 2022-06-02 16:32:33, Joe Lawrence wrote:
> The test_klp_callbacks_busy module conditionally blocks a future
> livepatch transition by busy waiting inside its workqueue function,
> busymod_work_func(). After scheduling this work, a test livepatch is
> loaded, introducing the transition under test.
>
> Both events are marked in the kernel log for later verification, but
> there is no synchronization to ensure that busymod_work_func() logs its
> function entry message before subsequent selftest commands log their own
> messages. This can lead to a rare test failure due to unexpected
> ordering like:
>
> --- expected
> +++ result
> @@ -1,7 +1,7 @@
> % modprobe test_klp_callbacks_busy block_transition=Y
> test_klp_callbacks_busy: test_klp_callbacks_busy_init
> -test_klp_callbacks_busy: busymod_work_func enter
> % modprobe test_klp_callbacks_demo
> +test_klp_callbacks_busy: busymod_work_func enter
> livepatch: enabling patch 'test_klp_callbacks_demo'
> livepatch: 'test_klp_callbacks_demo': initializing patching transition
> test_klp_callbacks_demo: pre_patch_callback: vmlinux
>
> Force the module init function to wait until busymod_work_func() has
> started (and logged its message), before exiting to the next selftest
> steps.
>
> Fixes: 547840bd5ae5 ("selftests/livepatch: simplify test-klp-callbacks busy target tests")
> Signed-off-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
> Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>
The patch has been committed into livepatching/livepatching.git,
branch for-5.20/selftests-fixes.
Best Regards,
Petr
