linux-kernel - [PATCH 03/23] iommu/dma: Use for_each_sg in iommu_dma

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Message-Id: <20190523070028.7435-4-hch@lst.de>
Date:   Thu, 23 May 2019 09:00:08 +0200
From:   Christoph Hellwig <hch@....de>
To:     Robin Murphy <robin.murphy@....com>
Cc:     Tom Murphy <tmurphy@...sta.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH 03/23] iommu/dma: Use for_each_sg in iommu_dma_alloc

arch_dma_prep_coherent can handle physically contiguous ranges larger
than PAGE_SIZE just fine, which means we don't need a page-based
iterator.

Signed-off-by: Christoph Hellwig <hch@....de>
Reviewed-by: Robin Murphy <robin.murphy@....com>
---
 drivers/iommu/dma-iommu.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index aac12433ffef..9b7f120d7381 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -606,15 +606,11 @@ struct page **iommu_dma_alloc(struct device *dev, size_t size, gfp_t gfp,
 		goto out_free_iova;
 
 	if (!(prot & IOMMU_CACHE)) {
-		struct sg_mapping_iter miter;
-		/*
-		 * The CPU-centric flushing implied by SG_MITER_TO_SG isn't
-		 * sufficient here, so skip it by using the "wrong" direction.
-		 */
-		sg_miter_start(&miter, sgt.sgl, sgt.orig_nents, SG_MITER_FROM_SG);
-		while (sg_miter_next(&miter))
-			arch_dma_prep_coherent(miter.page, PAGE_SIZE);
-		sg_miter_stop(&miter);
+		struct scatterlist *sg;
+		int i;
+
+		for_each_sg(sgt.sgl, sg, sgt.orig_nents, i)
+			arch_dma_prep_coherent(sg_page(sg), sg->length);
 	}
 
 	if (iommu_map_sg(domain, iova, sgt.sgl, sgt.orig_nents, prot)
-- 
2.20.1