From: Bryan Rittmeyer <bryan@staidm.org>
To: Danjel McGougan <danjel.mcgougan@comhem.se>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ppc32 copy_to_user dcbt fixup
Date: Sun, 14 Mar 2004 14:35:51 -0800 [thread overview]
Message-ID: <20040314223549.GA18082@staidm.org> (raw)
In-Reply-To: <40531D3D.2090702@comhem.se>
On Sat, Mar 13, 2004 at 03:39:57PM +0100, Danjel McGougan wrote:
> The obvious solution is to invalidate the dcache
> *after* DMA completion. It seems hard to guarantee that nobody will
> touch the memory area in question during the DMA.
You need to invalidate prior to submitting for DMA. Otherwise if the
region is dirty the CPU may write back after DMA has begun, causing a
data corrupting race.
Invalidating before _and_ after is expensive; better to fix the misreads.
-Bryan
next prev parent reply other threads:[~2004-03-14 22:34 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1z8Na-5hH-1@gated-at.bofh.it>
2004-03-13 14:39 ` [PATCH] ppc32 copy_to_user dcbt fixup Danjel McGougan
2004-03-14 22:35 ` Bryan Rittmeyer [this message]
2004-03-13 4:15 Bryan Rittmeyer
2004-03-13 4:50 ` Benjamin Herrenschmidt
2004-03-13 7:49 ` Bryan Rittmeyer
2004-03-13 8:36 ` Benjamin Herrenschmidt
2004-03-15 8:38 ` Segher Boessenkool
2004-03-13 9:11 ` Eugene Surovegin
2004-03-16 1:59 ` Bryan Rittmeyer
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