From: wsa@the-dreams.de (Wolfram Sang)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC PATCH 3/3] dma-mapping: clear dma_parms on teardown, too
Date: Fri, 14 Sep 2018 17:57:06 +0200 [thread overview]
Message-ID: <20180914155706.GA906@kunai> (raw)
In-Reply-To: <874f7cd9-ac51-5968-de40-14a0addf9c96@arm.com>
On Fri, Sep 14, 2018 at 02:23:51PM +0100, Robin Murphy wrote:
> On 13/09/18 16:17, Wolfram Sang wrote:
> > While sanitizig the pointer for dma_ops on teardown, do the same for
> > dma_parms, too. Rename the function to have a more generic name.
>
> Upon closer inspection, it looks like there are some cases (at least PCI and
> MFD) where dma_parms is installed by the parent/bus at device creation, and
> therefore remains valid and *would* be expected to persist across the child
> device's driver unbinding and rebinding - seems this is more complex than I
> first thought, sorry.
No problem. I am thankful I understand more details. So, the life cycle
of dma_parms is truly that of the device. Which means that the drivers
using devm_kzalloc in their probe, should ideally clear the pointer on
unbind. Otherwise, it is not possible to say if the non-NULL dma_parms
is intended or dangling. Which makes my initial dmam_set_dma_parms()
approach look not too bad, I'd think?
However, I don't want to push hard with this one. If you think this is
too academic, I'll just leave it for now...
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prev parent reply other threads:[~2018-09-14 15:57 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-13 15:17 [RFC PATCH 0/3] dma-mapping: clear dangling pointers consistently Wolfram Sang
2018-09-13 15:17 ` [RFC PATCH 1/3] ARM: dma-mapping: update comment about handling dma_ops when detaching from IOMMU Wolfram Sang
2018-09-14 12:15 ` Geert Uytterhoeven
2018-09-14 16:11 ` Wolfram Sang
2018-09-13 15:17 ` [RFC PATCH 2/3] dma-mapping: clear dma_ops pointer also on ARM Wolfram Sang
2018-09-14 13:12 ` Christoph Hellwig
2018-09-13 15:17 ` [RFC PATCH 3/3] dma-mapping: clear dma_parms on teardown, too Wolfram Sang
2018-09-14 13:12 ` Christoph Hellwig
2018-09-14 13:23 ` Robin Murphy
2018-09-14 15:57 ` Wolfram Sang [this message]
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