From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
Subject: Re: WARN_ON(irqs_disabled()) in dma_free_attrs?
Date: Fri, 2 Mar 2018 22:47:46 +0100
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To: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>
Cc: =?iso-8859-1?Q?J=FCrgen?= Urban <JuergenUrban-Mmb7MZpHnFY@public.gmane.org>, Fredrik Noring <noring-zgYzP9v7iJcdnm+yROfE0A@public.gmane.org>, Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
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On Fri, Mar 02, 2018 at 07:55:48PM +0000, Robin Murphy wrote:
> On the other hand, HCD_LOCAL_MEM implies a per-device coherent pool. Since 
> those bypass the arch-specific code, then depending on how unlikely we 
> think it is for devices covered by a single driver to exist both with and 
> without their own memory then it *might* also be reasonable to make the 
> change below. Christoph, what do you reckon?

For the case where the coherent pool really is per-device this looks
technically ok.  But it would also cover cases like arm nommu where
we have a single global nommu pool and we wouldn't warn for a driver
that frees with irqs disabled.

That being said I think allowing coherent frees from irqs disabled
context is a very bad idea to do in general, so if we can at all I'd
rather fix the driver than lifting any restrictions.