From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marek Szyprowski Subject: Re: [PATCH 4/4] ARM: dma-mapping: Skip cache maint for invalid page Date: Tue, 28 Aug 2012 23:58:48 +0200 Message-ID: <503D3F18.7070507@samsung.com> References: <1346154232-13299-1-git-send-email-hdoyu@nvidia.com> <1346154232-13299-4-git-send-email-hdoyu@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-2; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-reply-to: <1346154232-13299-4-git-send-email-hdoyu-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Hiroshi Doyu Cc: linaro-mm-sig-cunTk1MwBs8s++Sfvej+rw@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-tegra@vger.kernel.org Hello, On 8/28/2012 1:43 PM, Hiroshi Doyu wrote: > Skip cache maint for invalid page but warn it. > > Signed-off-by: Hiroshi Doyu > --- > arch/arm/mm/dma-mapping.c | 9 +++++++++ > 1 files changed, 9 insertions(+), 0 deletions(-) > > diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c > index 2621282..0368702 100644 > --- a/arch/arm/mm/dma-mapping.c > +++ b/arch/arm/mm/dma-mapping.c > @@ -1589,6 +1589,9 @@ static void arm_iommu_unmap_page(struct device *dev, dma_addr_t handle, > if (!iova) > return; > > + if (WARN_ON(!pfn_valid(page_to_pfn(page)))) > + return; > + > if (!dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs)) > __dma_page_dev_to_cpu(page, offset, size, dir); > > @@ -1607,6 +1610,9 @@ static void arm_iommu_sync_single_for_cpu(struct device *dev, > if (!iova) > return; > > + if (WARN_ON(!pfn_valid(page_to_pfn(page)))) > + return; > + > __dma_page_dev_to_cpu(page, offset, size, dir); > } > > @@ -1621,6 +1627,9 @@ static void arm_iommu_sync_single_for_device(struct device *dev, > if (!iova) > return; > > + if (WARN_ON(!pfn_valid(page_to_pfn(page)))) > + return; > + > __dma_page_cpu_to_dev(page, offset, size, dir); > } I really wonder what has happened in your system that you require such paranoid checks. All of the above functions are called on the scatter-list which has been first passed to dma_map_sg(). IMHO it makes much more sense to add a pfn_valid() check in dma_map_sg() and return error if the provided scatter list is not valid instead of these WARN_ONs. Best regards -- Marek Szyprowski Samsung Poland R&D Center