Message-ID: <1365093965.2609.116.camel@laptop>
Subject: Re: [PATCH v2 2/3] mutex: add support for reservation style locks,
 v2
From: Peter Zijlstra <peterz@infradead.org>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: Maarten Lankhorst <maarten.lankhorst@canonical.com>,
        linux-arch@vger.kernel.org, daniel.vetter@ffwll.ch, x86@kernel.org,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linaro-mm-sig@lists.linaro.org, robclark@gmail.com, tglx@linutronix.de,
        mingo@elte.hu, linux-media@vger.kernel.org
Date: Thu, 04 Apr 2013 18:46:05 +0200
In-Reply-To: <20130404133123.GW2228@phenom.ffwll.local>
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	 <1364921954.20640.22.camel@laptop> <1365076908.2609.94.camel@laptop>
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On Thu, 2013-04-04 at 15:31 +0200, Daniel Vetter wrote:
> I'm a bit confused about the different classes you're talking about.
> Since
> the ticket queue is currently a global counter there's only one class
> of
> ww_mutexes. 

Right, so that's not something that's going to fly.. we need to support
multiple users, including nesting of those. Again, you're adding
something to the generic kernel infrastructure, it had better be usable
:-)

> I guess we could change that once a second user shows up

No, we fix that before it all goes in. I would _so_ hate to find out it
cannot be 'fixed' and be stuck with a half-arsed sync primitive in the
core kernel that's only every usable by the one existent user.

So for now, forget all about TTM, DMA-BUF and other such coolness
except to verify that whatever we end up with does indeed work for the
case you need it for ;-)

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