Re: [PATCH bpf-next v2] selftests/bpf: Wait for wq callback before checking ok_sleepable

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] selftests/bpf: missing error jump before spin loop in serial_test_wq()
--

commit b67542c75142d5bd693ad5ed6fa8a0252549f42f
Author: Jonathan Bastari Thamrin <thamrinjonathan@gmail.com>

selftests/bpf: Wait for wq callback before checking ok_sleepable

This commit replaces the 50us sleep in serial_test_wq() with a spin loop
waiting for a wq_cb_run counter to be incremented by wq_cb_sleepable()
before checking ok_sleepable.

Link: https://github.com/kernel-patches/vmtest/issues/455

> diff --git a/tools/testing/selftests/bpf/prog_tests/wq.c b/tools/testing/selftests/bpf/prog_tests/wq.c
> index 97926e35aaf26..95ed4b69c0f50 100644
> --- a/tools/testing/selftests/bpf/prog_tests/wq.c
> +++ b/tools/testing/selftests/bpf/prog_tests/wq.c
> @@ -28,8 +28,9 @@ void serial_test_wq(void)
>  	ASSERT_OK(err, "test_run");
>  	ASSERT_EQ(topts.retval, 0, "test_run");
>  
> -	usleep(50); /* 10 usecs should be enough, but give it extra */
> -
> +	/* wait for wq callback to finish */
> +	while (!READ_ONCE(wq_skel->bss->wq_cb_run))
> +		sched_yield();

[Severity: Medium]
Can serial_test_wq() hang indefinitely here if bpf_prog_test_run_opts()
fails or if test_syscall_array_sleepable() -> test_elem_callback() in
tools/testing/selftests/bpf/progs/wq.c returns a non-zero error in
topts.retval before bpf_wq_start() schedules wq_cb_sleepable()?

Since ASSERT_OK() and ASSERT_EQ() only record the failure and evaluate to
false without returning or jumping to clean_up, execution falls through
into the while (!READ_ONCE(wq_skel->bss->wq_cb_run)) loop even when
wq_cb_sleepable() was never queued.

Should the assertions jump to clean_up on failure before entering the wait
loop, for example:

	if (!ASSERT_OK(err, "test_run") ||
	    !ASSERT_EQ(topts.retval, 0, "test_run"))
		goto clean_up;

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261102-wq-poll-fix-v2-1-48b7d12815b8@gmail.com?part=1