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From: Jung-uk Kim <jkim@FreeBSD.org>
To: John Baldwin <jhb@freebsd.org>
Date: Tue, 28 Sep 2010 18:29:06 -0400
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Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org,
	src-committers@freebsd.org, David Xu <davidxu@freebsd.org>
Subject: Re: svn commit: r213241 - in head: include lib/libthr/thread
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On Tuesday 28 September 2010 12:20 pm, Jung-uk Kim wrote:
> On Tuesday 28 September 2010 12:02 pm, Jung-uk Kim wrote:
> > On Tuesday 28 September 2010 09:31 am, John Baldwin wrote:
> > > On Tuesday, September 28, 2010 12:57:56 am David Xu wrote:
> > > > Author: davidxu
> > > > Date: Tue Sep 28 04:57:56 2010
> > > > New Revision: 213241
> > > > URL: http://svn.freebsd.org/changeset/base/213241
> > > >
> > > > Log:
> > > >   In current code, statically initialized and destroyed
> > > > object have same null value, the code can not distinguish
> > > > between them, to fix the problem, now a destroyed object is
> > > > assigned to a non-null value, and it will be rejected by some
> > > > pthread functions. PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP is
> > > > changed to number 1, so that adaptive mutex can be statically
> > > > initialized correctly.
> > >
> > > Does this fix PR threads/150889 then?
> >
> > It seems it does.
>
> Unfortunately, it seems to have a regression:
>
> %cat test.c
> #include <pthread.h>
> #include <stdio.h>
>
> static pthread_cond_t	static_cond = PTHREAD_COND_INITIALIZER;
> static pthread_mutex_t	static_mutex = PTHREAD_MUTEX_INITIALIZER;
>
> int
> main(void)
> {
>
> 	// pthread_mutex_lock(&static_mutex);
> 	printf("%d\n", pthread_cond_wait(&static_cond, &static_mutex));
> 	pthread_mutex_unlock(&static_mutex);
>
> 	return (0);
> }
> %cc -o test test.c -pthread
> %./test
> Segmentation fault (core dumped)
>
> pthread_cond_wait(3) had to return EPERM here. :-(

I realized it is a libthr "feature" to catch real application bugs and 
to increase performance by not checking rare conditions, I guess. :-/

Sorry for the noise,

Jung-uk Kim