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Thu, 4 Nov 2021 12:36:50 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 3B8521063; Thu, 4 Nov 2021 05:36:50 -0700 (PDT) Received: from [10.57.80.217] (unknown [10.57.80.217]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A3F3D3F7D7; Thu, 4 Nov 2021 05:36:49 -0700 (PDT) Message-ID: Date: Thu, 4 Nov 2021 12:36:16 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:91.0) Gecko/20100101 Thunderbird/91.2.1 Subject: Re: [PATCH 05/10] dma-direct: factor out a helper for DMA_ATTR_NO_KERNEL_MAPPING allocations Content-Language: en-GB To: Christoph Hellwig , iommu@lists.linux-foundation.org References: <20211021090611.488281-1-hch@lst.de> <20211021090611.488281-6-hch@lst.de> From: Robin Murphy In-Reply-To: <20211021090611.488281-6-hch@lst.de> Cc: David Rientjes X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On 2021-10-21 10:06, Christoph Hellwig wrote: > Split the code for DMA_ATTR_NO_KERNEL_MAPPING allocations into a separate > helper to make dma_direct_alloc a little more readable. > > Signed-off-by: Christoph Hellwig > Acked-by: David Rientjes > --- > kernel/dma/direct.c | 31 ++++++++++++++++++++----------- > 1 file changed, 20 insertions(+), 11 deletions(-) > > diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c > index a6b6fe72af4d1..4ffdb524942a1 100644 > --- a/kernel/dma/direct.c > +++ b/kernel/dma/direct.c > @@ -163,6 +163,24 @@ static void *dma_direct_alloc_from_pool(struct device *dev, size_t size, > return ret; > } > > +static void *dma_direct_alloc_no_mapping(struct device *dev, size_t size, > + dma_addr_t *dma_handle, gfp_t gfp) > +{ > + struct page *page; > + > + page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO); > + if (!page) > + return NULL; > + > + /* remove any dirty cache lines on the kernel alias */ > + if (!PageHighMem(page)) > + arch_dma_prep_coherent(page, size); > + > + /* return the page pointer as the opaque cookie */ > + *dma_handle = phys_to_dma_direct(dev, page_to_phys(page)); > + return page; > +} > + > void *dma_direct_alloc(struct device *dev, size_t size, > dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs) > { > @@ -175,17 +193,8 @@ void *dma_direct_alloc(struct device *dev, size_t size, > gfp |= __GFP_NOWARN; > > if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) && > - !force_dma_unencrypted(dev) && !is_swiotlb_for_alloc(dev)) { > - page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO); > - if (!page) > - return NULL; > - /* remove any dirty cache lines on the kernel alias */ > - if (!PageHighMem(page)) > - arch_dma_prep_coherent(page, size); > - *dma_handle = phys_to_dma_direct(dev, page_to_phys(page)); > - /* return the page pointer as the opaque cookie */ > - return page; > - } > + !force_dma_unencrypted(dev) && !is_swiotlb_for_alloc(dev)) Hmm, does force_dma_unencrypted() actually matter if the caller doesn't want to access the buffer itself? Presumably any subsequent mmap() to userspace would still do the right thing? Robin. > + return dma_direct_alloc_no_mapping(dev, size, dma_handle, gfp); > > if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED) && > !IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) && > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu