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Re: pthread_rwlock_rdlock() returns EDEADLK when trying to call it > once
- From: Christopher Faylor <cgf-use-the-mailinglist-please at cygwin dot com>
- To: cygwin at cygwin dot com
- Date: Mon, 1 Dec 2008 22:07:04 -0500
- Subject: Re: pthread_rwlock_rdlock() returns EDEADLK when trying to call it > once
- References: <aa7d410c0812011241n21a0b6du5c738f9cc88b9257@mail.gmail.com>
- Reply-to: cygwin at cygwin dot com
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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