linux-kernel - Re: [PATCH] net: wireless: airo semaphore to mutex

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Message-ID: <20080527021503.GH30894@parisc-linux.org>
Date:	Mon, 26 May 2008 20:15:03 -0600
From:	Matthew Wilcox <matthew@....cx>
To:	Rusty Russell <rusty@...tcorp.com.au>
Cc:	Michal Schmidt <mschmidt@...hat.com>,
	Daniel Walker <dwalker@...sta.com>, linville@...driver.com,
	mingo@...e.hu, linux-kernel@...r.kernel.org,
	linux-wireless@...r.kernel.org, arjan@...radead.org
Subject: Re: [PATCH] net: wireless: airo semaphore to mutex

On Tue, May 27, 2008 at 11:17:22AM +1000, Rusty Russell wrote:
> On Tuesday 27 May 2008 03:29:14 Michal Schmidt wrote:
> > Mutexes are not allowed in interrupt context, not even mutex_trylock.
> 
> As an aside, does anyone know why?  I know the documentation says so, but it 
> wasn't immediately obvious to me.  I asked before to no response...

Because mutexes have an owner.  In interrupt context, there is no owner.
This owner is used to do priority boosts as well as debugging.

-- 
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operating system, but compare it to ours.  We can't possibly take such
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