Re: [PATCH] nptl: Handle NULL abstime [BZ #26394]

["H.J. Lu via Libc-alpha" <libc-alpha@sourceware.org>]

On Mon, Aug 17, 2020 at 6:30 AM Lukasz Majewski <lukma@denx.de> wrote:
>
> Hi Andreas, H.J.,
>
> > On Aug 15 2020, H.J. Lu wrote:
> >
> > > From fa1f97680fca290a378c449f2b63682ee348fd2c Mon Sep 17 00:00:00
> > > 2001 From: "H.J. Lu" <hjl.tools@gmail.com>
> > > Date: Sat, 15 Aug 2020 11:06:35 -0700
> > > Subject: [PATCH] nptl: Handle NULL abstime [BZ #26394]
> > >
> > > Since abstime passed to pthread_{clock|timed}join_np may be NULL,
>
> Could you point me to the exact reference that it is allowed (or
> required) to pass NULL to this syscall?
>
> The one which I've found on the web:
> https://linux.die.net/man/3/pthread_timedjoin_np
>
> doesn't mention about NULL pointer passed as the absolute time.
> It says explicitly:
> "The abstime argument is a structure of the following form, specifying
> an absolute time measured since the Epoch"
>
>
> As fair as I remember [1] glibc only handles the NULL pointer case when
> it is explicitly written in the documentation/spec that NULL is passed
> (like here: https://linux.die.net/man/2/timerfd_settime or here:
> https://linux.die.net/man/2/utimensat).
>
> Link:
> [1] -
> https://sourceware.org/pipermail/libc-alpha/2019-November/108072.html
>

sysdeps/pthread/tst-join14.c explicitly passes NULL:

static int
do_test_clock (clockid_t clockid)
{
  pthread_t th = xpthread_create (NULL, tf, NULL);

  void *status;
  int val = (clockid == CLOCK_USE_TIMEDJOIN)
    ? pthread_timedjoin_np (th, &status, NULL)
    : pthread_clockjoin_np (th, &status, clockid, NULL);
  TEST_COMPARE (val, 0);

  if (status != (void *) 42l)
    FAIL_EXIT1 ("return value %p, expected %p\n", status, (void *) 42l);

  return 0;
}

-- 
H.J.