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* Re: POSIX writer locks can't be recursive
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@ 2020-06-26  8:54 ` Michael Kerrisk (man-pages)
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From: Michael Kerrisk (man-pages) @ 2020-06-26  8:54 UTC (permalink / raw)
  To: Kumar Kartikeya Dwivedi; +Cc: mtk.manpages, Carlos O'Donell, linux-man

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/

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2020-06-26  8:54 ` POSIX writer locks can't be recursive Michael Kerrisk (man-pages)

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