objective-c mutex deallocation bug

[Ovidiu Predescu]

Looks good, I applied it.

Thanks,
Ovidiu

On Tue, 28 Sep 1999 16:44:45 -0700, Chris Ball <cball@fmco.com> wrote:

> I have sent this patch before but it has never appeared
> so here it goes again.  If it is easier to give me cvs
> write access I will be happy to check in the change 
> myself.
> 
> 
> 
> >Date: Wed, 26 May 1999 17:32:18 -0700
> >To: egcs-bugs@egcs.cygnus.com
> >From: Chris Ball <cball@fmco.com>
> >Subject: objective-c mutex deallocation bug
> >Cc: tmartin@fmco.com, yonas
> >
> >Problem Description:
> >	pthread_mutex_destroy() will fail or have undefined
> >	behaviour if called with a locked mutex.
> >
> >	objc_mutex_deallocate() locks the mutex it is trying
> >	to release to establish ownership.  This lock is not
> >	released before calling __objc_mutex_deallocate() in
> >	thr-posix.c.
> >
> >	Results:  All mutex deallocate/release calls fail 
> >		under linux when using the posix thread 
> >		library.
> >
> >
> >Versions Found to have Problem:
> >	gcc version egcs-2.90.29 980515 (egcs-1.0.3 release)
> >	to
> >	gcc version egcs-2.91.66 19990314 (egcs-1.1.2 release)
> >
> >	and probably many older releases.
> 
> and now in gcc-2.95.1.
> 
> >
> >Notes:
> >	The behaviour of pthread_mutex_destroy() was checked
> >	via man pages for solaris 2.6 and linux using the
> >	posix thread library version 0.7.
> >
> >
> >Solution:
> >	This patch to thr-posix.c fixes the problem.  This
> >	releases all locks on the mutex so that in the case
> >	of a recursive lock the pthread_mutex_destroy() call
> >	will be successful.
> >
> >
> >diff -c output:
> 
> diff redone as -c3p...
> 
> *** thr-posix.c.old	Thu Sep 23 07:19:12 1999
> --- thr-posix.c.new	Thu Sep 23 07:19:12 1999
> *************** __objc_mutex_allocate(objc_mutex_t mutex
> *** 145,150 ****
> --- 145,164 ----
>   int
>   __objc_mutex_deallocate(objc_mutex_t mutex)
>   {
> + 	int count = 1;
> + 
> + 	/*
> + 	 * Posix Threads specifically require that the thread be unlocked for
> + 	 * pthread_mutex_destroy to work.
> + 	 */
> + 
> + 	while ( count )
> + 	{
> + 		 if (( count = pthread_mutex_unlock((pthread_mutex_t *)mutex->backend))
> + 			< 0 )
> + 		  	return -1;
> + 	}
> + 
>     if (pthread_mutex_destroy((pthread_mutex_t *)mutex->backend))
>       return -1;
>   
> 
> 
> ChangeLog entry:
> 
> Thu Sep 23 07:19:12 1999   Chris Ball <cball@fmco.com>
> 
> 	* thr-posix.c (__objc_mutex_deallocate): made deallocate work.
> 
> 
> 	Chris.
>