Subject: Re: [RFC,PATCH 1/2] Add a common struct clk
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Lothar =?ISO-8859-1?Q?Wa=DFmann?= <LW@KARO-electronics.de>
Cc: Jeremy Kerr <jeremy.kerr@canonical.com>, Ben Dooks <ben-linux@fluff.org>,
       linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
       Uwe =?ISO-8859-1?Q?Kleine-K=F6nig?= 
	<u.kleine-koenig@pengutronix.de>
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Date: Mon, 14 Jun 2010 19:22:58 +1000
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On Mon, 2010-06-14 at 08:39 +0200, Lothar Waßmann wrote:
> All implementations so far use spin_lock_irq_save()!

Nothing prevents your implementation to be a tad smarter.

> How would you be able to sleep with a mutex held?
> If you hold a lock you must not sleep, no matter what sort of lock it
> is. 

You can perfectly sleep with a mutex held. You -do- have to be careful
of course to ensure you aren't going to do silly thing like re-enter and
try to take it twice, or A->B B->A deadlocks, but in the typical case of
wanting to use a msleep rather than udelay, it works very well :-)

Cheers,
Ben.


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