From owner-freebsd-threads@FreeBSD.ORG  Mon Oct 24 16:41:03 2005
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Date: Mon, 24 Oct 2005 12:41:01 -0400 (EDT)
From: Daniel Eischen <deischen@freebsd.org>
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To: Sven Berkvens-Matthijsse <sven@ilse.net>
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Cc: Marc Olzheim <marcolz@stack.nl>, Marc Olzheim <marcolz@ilse.net>,
	David Xu <davidxu@freebsd.org>, freebsd-threads@freebsd.org
Subject: Re: threads/76690: fork hang in child for (-lc_r & -lthr)
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On Mon, 24 Oct 2005, Sven Berkvens-Matthijsse wrote:
> > It may even be enough just to set __isthreaded to 0 in the child
> > after the fork() before calling any malloc()'s and free()'s so they
> > don't try to use the lock.
>
> But then the free() in the child process may be using an unstable
> state of the malloc system (because if you don't acquire the lock
> before the fork(), malloc() may be busy in the middle of the fork()).

I don't think that can happen because libc_r will not switch out
a thread that is in a critical region (and libc locks are critical
regions) until it leaves the region.

-- 
DE