linux-kernel - Re: IrDA driver fails on PXA255

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Message-ID: <20110531210027.GA3660@n2100.arm.linux.org.uk>
Date:	Tue, 31 May 2011 22:00:27 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	David Rientjes <rientjes@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
	Nicolas Pitre <nicolas.pitre@...aro.org>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Eric Miao <eric.y.miao@...il.com>,
	Samuel Ortiz <samuel@...tiz.org>
Subject: Re: IrDA driver fails on PXA255

On Tue, May 31, 2011 at 01:03:03PM -0700, David Rientjes wrote:
> The problem certainly isn't being ignored in this thread, or in the patch 
> that I sent to fix Dmitry's issue by default, so that doesn't seem to be 
> the case.  What would be ignored, though, is if it just emitted a 
> WARN_ON() without failing the allocation so everything works perfectly.

Sorry, you did not send a patch to fix it.  You sent a *bodge* to enable
the DMA zone.  As long as you insist that's a valid fix, you're going
to carry zero credibility with me.

The fact is that this driver should not be using GFP_DMA to allocate
things which aren't even DMA buffers, and its use of GFP_DMA should be
removed.  But rather than look at that and work it out, and then produce
a patch to sort that out, the only thing you can do is come up with
bodge to enable the DMA zone, and continue to insist that's the right
solution.

I repeat, enabling the DMA zone for this driver is a pure and utter
bodge, and the change to make these allocations fail _will_ and _has_
caused regressions.

Your whinge that we should re-enable the DMA zone which has been
disabled for quite a long time now to work around this new restriction
is extremely idiotic.

Do the right thing.  Make allocations to GFP_DMA zones _warn_ first for
a cycle so that affected drivers can be fixed.  Then for the next cycle,
make it a hard failure.
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