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From: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
To: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Cc: "Carlos O'Donell" <carlos@redhat.com>,
	linux-man <linux-man@vger.kernel.org>
Subject: Re: POSIX writer locks can't be recursive
Date: Wed, 15 Jul 2020 21:50:48 +0200
Message-ID: <CAKgNAkhLgzog_DjePBh5mHMfesmc5aWpURPHrCXLJMXQWZFYTg@mail.gmail.com> (raw)
In-Reply-To: <8d7edc37-6b5f-1dd9-5f7f-b4e15a9ae39a@gmail.com>

Hi Carlos,

Ping!

Thanks,

Michael

On Fri, 26 Jun 2020 at 10:54, Michael Kerrisk (man-pages)
<mtk.manpages@gmail.com> wrote:
>
> Hi Carlos,
>
> Could you comment here, as this was your text in pthread_rwlockattr_setkind_np(3)?
>
> On 6/25/20 2:32 PM, Kumar Kartikeya Dwivedi wrote:
> > Hi,
> > In pthread_rwlockattr_setkind_np(3), the explanation for
> > PTHREAD_RWLOCK_PREFER_WRITER_NP reads:
> >
> >> This is ignored by glibc because the POSIX requirement to support
> >> recursive writer locks would cause this option to create trivial
> >> deadlocks;
> >
> > I think this should be "reader locks" instead, since it is
> > undefined[1] for a thread holding a write lock to call
> > pthread_rwlock_wrlock(3) again (glibc returns EDEADLK, musl simply
> > deadlocks). There's no such requirement in POSIX either. Please let me
> > know if I'm missing something.
> >
> > [1]: https://pubs.opengroup.org/onlinepubs/007908799/xsh/pthread_rwlock_wrlock.html
>
> Cheers,
>
> Michael
>
> --
> Michael Kerrisk
> Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
> Linux/UNIX System Programming Training: http://man7.org/training/



-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/

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Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CAP01T764kz5T+m+8sV0o30enBL1TagF7RQSjU0XcVJ0PvL0PTg@mail.gmail.com>
2020-06-26  8:54 ` Michael Kerrisk (man-pages)
2020-07-15 19:50   ` Michael Kerrisk (man-pages) [this message]
2020-07-16 19:50     ` [PATCH] pthread_rwlockattr_setkind_np.3: PTHREAD_RWLOCK_PREFER_WRITER_NP Carlos O'Donell
2020-07-17  8:05       ` Michael Kerrisk (man-pages)

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