[LTP] [PATCH v2 1/3] syscalls/tgkill01: add new test

[Sumit Garg]

On Thu, 14 Mar 2019 at 19:29, Cyril Hrubis <chrubis@suse.cz> wrote:
>
> Hi!
> > I am not sure how we would manage actual "msec_timeout" in case we get
> > EINTR and need to retry again as we may need to take care of elapsed
> > time till we receive asynchronous signal.
>
> I would have just restarted the timeout after we got signal, the worst case
> that can happen is that in an unlikely case we will send a signals fast enough
> so that the checkpoint will never timeout. But even then the test library will
> timeout and would kill the process anyways.
>
> Another option is to switch checkpoints so that they use absolute timeout and
> pass clock_gettime() + msec_timeout as timeout.
>
> I would go for something as simple as:
>
> diff --git a/lib/tst_checkpoint.c b/lib/tst_checkpoint.c
> index 5455d0378..5e5b11496 100644
> --- a/lib/tst_checkpoint.c
> +++ b/lib/tst_checkpoint.c
> @@ -85,6 +85,7 @@ void tst_checkpoint_init(const char *file, const int lineno,
>  int tst_checkpoint_wait(unsigned int id, unsigned int msec_timeout)
>  {
>         struct timespec timeout;
> +       int ret;
>
>         if (id >= tst_max_futexes) {
>                 errno = EOVERFLOW;
> @@ -94,8 +95,12 @@ int tst_checkpoint_wait(unsigned int id, unsigned int msec_timeout)
>         timeout.tv_sec = msec_timeout/1000;
>         timeout.tv_nsec = (msec_timeout%1000) * 1000000;
>
> -       return syscall(SYS_futex, &tst_futexes[id], FUTEX_WAIT,
> -                      tst_futexes[id], &timeout);
> +       do {
> +               ret = syscall(SYS_futex, &tst_futexes[id], FUTEX_WAIT,
> +                             tst_futexes[id], &timeout);
> +       } while (ret == -1 && errno == EINTR);
> +
> +       return ret;
>  }
>

Wouldn't this loop be more appropriate in
"tst_safe_checkpoint_wait()"? As at later stage we may have tests that
depends on checkpoints being interrupted by signals and could directly
use "tst_checkpoint_wait()".

-Sumit

> --
> Cyril Hrubis
> chrubis@suse.cz