Re: futex timeout not working? (bisected)
From: Thomas Gleixner
Date: Fri Oct 16 2015 - 06:36:11 EST
On Fri, 16 Oct 2015, Heiko Carstens wrote:
> On Fri, Oct 16, 2015 at 12:21:51PM +0200, Thomas Gleixner wrote:
> > Heiko,
> >
> > On Thu, 15 Oct 2015, Heiko Carstens wrote:
> > > /* We wait for half a second. */
> > > ts.tv_nsec += 500000000;
> > > if (ts.tv_nsec >= 1000000000)
> > > {
> > > ++ts.tv_sec;
> > > ts.tv_nsec -= 1000000000;
> > > }
> > >
> > > ret = syscall (__NR_futex, &futex_word, op, expected, ts, NULL, FUTEX_BITSET_MATCH_ANY);
> >
> > If you actually hand in a pointer to 'ts' then the program works as
> > expected even with the commit in question applied.
>
> Yes, sorry about that! I was just about to write that this should have
> been &ts on x86. Since x86 seems to pass also structures >8 bytes by
> value.
>
> However on s390 it is passed by reference. So even it I change ts to &ts,
> it will hang as I described.
>
> So you are saying this works on x86 and it must be some s390 specific bug?
Looks like. I have no idea why that would break on s390. Did you try
to revert the commit on top of tree?
Thanks,
tglx
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