From: Torvald Riegel <triegel@redhat.com>
To: Florian Weimer <fweimer@redhat.com>
Cc: GLIBC Devel <libc-alpha@sourceware.org>,
vl@samba.org, Michael Adam <madam@redhat.com>,
Rich Felker <dalias@libc.org>
Subject: Re: [PATCH][BZ #20973] Robust mutexes: Fix lost wake-up.
Date: Fri, 16 Dec 2016 22:13:00 -0000 [thread overview]
Message-ID: <1481926413.14990.628.camel@redhat.com> (raw)
In-Reply-To: <7415d701-9dab-3c99-2716-2dcd3a4ac731@redhat.com>
On Fri, 2016-12-16 at 15:11 +0100, Florian Weimer wrote:
> On 12/15/2016 11:29 PM, Torvald Riegel wrote:
> > diff --git a/nptl/pthread_mutex_lock.c b/nptl/pthread_mutex_lock.c
> > index bdfa529..01ac75e 100644
> > --- a/nptl/pthread_mutex_lock.c
> > +++ b/nptl/pthread_mutex_lock.c
> > @@ -182,6 +182,11 @@ __pthread_mutex_lock_full (pthread_mutex_t *mutex)
> > &mutex->__data.__list.__next);
> >
> > oldval = mutex->__data.__lock;
> > + /* This is set to FUTEX_WAITERS iff we might have shared the
>
> âiffâ doesn't seem to be correct here because it's not an exact
> equivalence, âifâ is sufficient.
No, I think the iff is correct. We do only set it if we may have shared
the flag.
> > @@ -190,9 +195,9 @@ __pthread_mutex_lock_full (pthread_mutex_t *mutex)
> > /* The previous owner died. Try locking the mutex. */
> > int newval = id;
> > #ifdef NO_INCR
> > - newval |= FUTEX_WAITERS;
> > + newval |= FUTEX_WAITERS | assume_other_futex_waiters;
> > #else
> > - newval |= (oldval & FUTEX_WAITERS);
> > + newval |= (oldval & FUTEX_WAITERS) | assume_other_futex_waiters;
> > #endif
>
> The NO_INCR change is quite confusing. Perhaps drop it and add a comment?
Yes.
> VL, what is the copyright status of your test case?
So, I'll wait a little to see how the test case question resolved, and
then commit it with the one change above either with or without a test
case. If anyone objects to that, please speak up.
next prev parent reply other threads:[~2016-12-16 22:13 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-15 22:27 Torvald Riegel
2016-12-15 22:29 ` Torvald Riegel
2016-12-16 14:11 ` Florian Weimer
2016-12-16 14:45 ` Volker Lendecke
[not found] ` <CAJ+X7mT1cU1_2ON2JZM9oYMP_cak734tkf+PZJeo4MZg1i4gmw@mail.gmail.com>
2016-12-19 17:15 ` Florian Weimer
2016-12-16 22:13 ` Torvald Riegel [this message]
2016-12-19 19:47 ` Florian Weimer
2016-12-19 20:30 ` Carlos O'Donell
2016-12-20 15:03 ` Torvald Riegel
2016-12-19 18:20 ` Carlos O'Donell
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