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Date: Thu, 05 Apr 2007 10:33:24 +0800
From: David Xu <davidxu@freebsd.org>
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To: Ed Maste <ed.maste@gmail.com>
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Cc: freebsd-threads@freebsd.org
Subject: Re: [PATCH] libthr - pthread_set_name_np crash
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Ed Maste wrote:
> It seems there is a bug in pthread_set_name_np for the thread != curthread
> case.  That is, pthread_set_name_np called from outside of the thread
> being named, as in the following example:
> 
>        pthread_create(&pt, 0, t_spin, (void *)1);
>        [...]
>        pthread_set_name_np(pt, "t1");
> 
> The bug is a race condition that leads to thread->locklevel being
> incorrect.  Based on the other cases of locking a not-curthread thread,
> I think the patch below is the fix.  Can a libthr expert comment?
> 
> Thanks,
> Ed
> 
> Index: thr_info.c
> ===================================================================
> RCS file: /usr/cvs/src/lib/libthr/thread/thr_info.c,v
> retrieving revision 1.9
> diff -u -r1.9 thr_info.c
> --- thr_info.c  12 Jan 2007 07:26:20 -0000      1.9
> +++ thr_info.c  23 Mar 2007 14:56:13 -0000
> @@ -52,12 +52,12 @@
>                        ret = errno;
>        } else {
>                if (_thr_ref_add(curthread, thread, 0) == 0) {
> -                       THR_LOCK(thread);
> +                       THR_THREAD_LOCK(curthread, thread);
>                        if (thread->state != PS_DEAD) {
>                                if (thr_set_name(thread->tid, name))
>                                        ret = errno;
>                        }
> -                       THR_UNLOCK(thread);
> +                       THR_THREAD_UNLOCK(curthread, thread);
>                        _thr_ref_delete(curthread, thread);
>                } else {
>                        ret = ESRCH;

Yes, this patch is correct, please commit it.

Regards,
David Xu