linux-kernel - Re: [PATCH 2/2] dma:of: Use a mutex to protect the of_dma

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Message-Id: <201304201238.08908.arnd@arndb.de>
Date:	Sat, 20 Apr 2013 12:38:08 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	"Lars-Peter Clausen" <lars@...afoo.de>
Cc:	Jon Hunter <jon-hunter@...com>, Vinod Koul <vinod.koul@...el.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] dma:of: Use a mutex to protect the of_dma_list

On Saturday 20 April 2013, Lars-Peter Clausen wrote:
> On 04/20/2013 12:45 AM, Jon Hunter wrote:
> > I think that there is a problem here. For controllers using the
> > of_dma_simple_xlate(), this will call dma_request_channel() which also
> > uses a mutex.
> 
> That would only be a problem if it'd use the same mutex. Holding two mutexes at
> the same time is not a problem per se.
> 

I guess Jon originlly tried it with a spinlock as the outer lock, which indeed
does not work, but the new version does not have this problem.

	Arnd
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