Re: [PATCH] selftests/cgroup: Fix intermittent test_cgfreezer_ptrace test failures

[Tejun Heo <tj@kernel.org>]

Hello, Waiman.

> +	usleep(1000);
>  	if (cg_check_frozen(cgroup, true))
>  		goto cleanup;

A fixed 1ms sleep only hides the race. On a loaded machine or a slow arch
(you mention ppc64) the refreeze can take longer than 1ms, and the test
reads the unfrozen state and fails anyway.

The freezer test already has a way to wait for this properly.
cg_prepare_for_wait() sets up an inotify watch on cgroup.events and
cg_wait_for() blocks until it changes. cg_enter_and_wait_for_frozen() shows
the pattern: loop cg_wait_for() then cg_check_frozen(). The cgroup always
ends up frozen, so looping until cg_check_frozen() reports frozen is
reliable and doesn't depend on timing.

Can you respin using that instead of usleep()?

Also, temporaily -> temporarily, in both the changelog and the comment.

Thanks.

-- 
tejun