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Date: Thu, 19 Apr 2001 09:43:42 -0700 (PDT)
From: Linus Torvalds <torvalds@transmeta.com>
To: Alexander Viro <viro@math.psu.edu>
cc: Abramo Bagnara <abramo@alsa-project.org>, Alon Ziv <alonz@nolaviz.org>,
        Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Mike Kravetz <mkravetz@sequent.com>,
        Ulrich Drepper <drepper@cygnus.com>
Subject: Re: light weight user level semaphores
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On Thu, 19 Apr 2001, Alexander Viro wrote:
>
> I certainly agree that introducing ioctl() in _any_ API is a shootable
> offense. However, I wonder whether we really need any kernel changes
> at all.

I'd certainly be interested in seeing the pipe-based approach. Especially
if you make the pipe allocation lazy. That isn'tr trivial (it needs to be
done right with both up_failed() and down_failed() trying to allocate the
pipe on contention and using an atomic cmpxchg-style setting if none
existed before). It has the BIG advantage of working on old kernels, so
that you don't need to have backwards compatibility cruft in the
libraries.

		Linus

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