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Date:	Mon, 1 Dec 2008 22:07:04 -0500
From:	Christopher Faylor <cgf-use-the-mailinglist-please AT cygwin DOT com>
To:	cygwin AT cygwin DOT com
Subject:	Re: pthread_rwlock_rdlock() returns EDEADLK when trying to call it > once
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On Mon, Dec 01, 2008 at 09:41:53PM +0100, kalle ko wrote:
>Possible bug in winsup/cygwin/thread.cc:
>...
>int
>pthread_rwlock::rdlock ()
>{
>  int result = 0;
>  struct RWLOCK_READER *reader;
>  pthread_t self = pthread::self ();
>
>  mtx.lock ();
>
>  if (lookup_reader (self))
>    {
>      result = EDEADLK;
>      goto DONE;
>    }
>...
>
>It doesn't seem like it's possible for a thread to call
>pthread_rwlock_rdlock() multiple times, and if a thread does, it will get
>a EDEADLK error.
>
>http://opengroup.org/onlinepubs/007908799/xsh/pthread_rwlock_rdlock.html:
>	...
>	A thread may hold multiple concurrent read locks on rwlock (that is,
>	successfully call the pthread_rwlock_rdlock() function n times).
>	...
>	[EDEADLK]
>	    The current thread already owns the read-write lock for writing.
>	...
>
>I noticed this when one of my tests failed.

You've located the code.  Feel free to suggest a patch.

cgf

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