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Date: Sun, 17 Nov 2002 10:54:42 -0800 (PST)
From: Linus Torvalds <torvalds@transmeta.com>
To: Ulrich Drepper <drepper@redhat.com>
cc: Ingo Molnar <mingo@elte.hu>, Luca Barbieri <ldb@ldb.ods.org>,
       Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [patch] threading fix, tid-2.5.47-A3
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On Sun, 17 Nov 2002, Ulrich Drepper wrote:
> 
> It doesn't do this.  Ingo's description simply wasn't right.
> 
> The syscall is used in one place and this is when the thread library
> gets initialized.  I never gets used unconditionally and in situations
> where the process is not prepared.

Ok, good. That means that "sys_set_userpid()" is fine with me.

That still leaves the other part of the patch. I do not think that SETTID
and CLEARTID should be mixed together. There are perfectly valid reasons
why a parent wants SETTID even when it _doesn't_ want CLEARTID.

In fact, SETTID is clearly useful even without threads, and exactly for
the case that Ingo apparently broke with his patch: the parent wants to
atomically save the TID of the child in the _parents_ address space (so
that a immediate SIGCHLD won't be racy with saving off the pid by the
parent).

So Ingo, please send me just the sys_set_userpid() parts, and revert your 
broken code that made SETTID do bad things and only work for threads.

There's no reason to make SETTID/CLEARTID be one flag, since they are
clearly different things, and NPTL can just always set both bits if that
is the behaviour glibc wants (and I agree with that behaviour, of course. 
I just disagree with not allowing others to do different things).

			Linus


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