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From: <benh@kernel.crashing.org>
To: Linus Torvalds <torvalds@transmeta.com>,
        Martin Dalecki <dalecki@evision-ventures.com>
Cc: Jens Axboe <axboe@suse.de>,
        Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] 2.5.15 IDE 62
Date: Mon, 13 May 2002 19:02:38 +0100
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>And then you make sure that nobody EVER uses any other lock than the queue
>lock.

Except that some controllers are perfectly safe to use both channels
at the same time, except when dealing with rare and sensible operations
(like changing channel settings) where a common set of registers is
shared between channels.

The controller driver in this case will want a lock per channel queue
and an internal lock to protect access to these shared registers. But
that lock can (and has to be) hidden in the controller driver.

Ben.