Re: [PATCH 2/2] ksefltest: pidfd: Fix wait_states: Test terminated by timeout

[Shuah Khan]

On 10/29/21 2:32 AM, Christian Brauner wrote:
> On Fri, Oct 29, 2021 at 10:45:28AM +0800, Li Zhijian wrote:
> > 0Day/LKP observed that the kselftest blocks foever since one of the
> > pidfd_wait doesn't terminate in 1 of 30 runs. After digging into
> > the source, we found that it blocks at:
> > ASSERT_EQ(sys_waitid(P_PIDFD, pidfd, &info, WCONTINUED, NULL), 0);
> >
> > we can reproduce it by:
> > $ while true; do make run_tests -C pidfd; done
> >
> > a delay to ensure that the parent can see child process WCONTINUED.
> >
> > CC: Christian Brauner <christian@xxxxxxxxxx>
> > CC: Shuah Khan <shuah@xxxxxxxxxx>
> > CC: Philip Li <philip.li@xxxxxxxxx>
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > Signed-off-by: Li Zhijian <lizhijian@xxxxxxxxxxxxxx>
> > ---
>
> Not a fan of the usleep() solution but if it fixes it it's fine for
> a test, I think.
> Acked-by: Christian Brauner <christian.brauner@xxxxxxxxxx>

I don't like introducing usleep() which will increase the kselftest
run-time. Every little bit adds up if we allow usleep() in tests.

thanks,
-- Shuah