Re: futex timeout not working? (bisected)

From: Heiko Carstens
Date: Fri Oct 16 2015 - 06:31:36 EST


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?

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