linux-kernel - [RFC PATCH 01/16] dmaengine: ste_dma40, imx-dma: Cleanup scatterlist layering violations

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Date:   Wed, 24 May 2017 15:42:12 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        linux-nvdimm@...ts.01.org, linux-nvme@...ts.infradead.org,
        linux-rdma@...r.kernel.org
Cc:     Christoph Hellwig <hch@....de>,
        Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        Jens Axboe <axboe@...nel.dk>,
        Dan Williams <dan.j.williams@...el.com>,
        Ross Zwisler <ross.zwisler@...ux.intel.com>,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Ming Lei <ming.lei@...onical.com>,
        Johannes Berg <johannes.berg@...el.com>,
        Stephen Bates <sbates@...thlin.com>,
        Sagi Grimberg <sagi@...mberg.me>,
        Keith Busch <keith.busch@...el.com>,
        Christian König <christian.koenig@....com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Jerome Glisse <jglisse@...hat.com>,
        Logan Gunthorpe <logang@...tatee.com>
Subject: [RFC PATCH 01/16] dmaengine: ste_dma40, imx-dma: Cleanup scatterlist layering violations

Two dma engine drivers directly accesses page_link assuming knowledge
that should be contained only in scatterlist.h.

We replace these with calls to sg_chain and sg_assign_page.

Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
Signed-off-by: Stephen Bates <sbates@...thlin.com>
---
 drivers/dma/imx-dma.c   | 7 ++-----
 drivers/dma/ste_dma40.c | 5 +----
 2 files changed, 3 insertions(+), 9 deletions(-)

diff --git a/drivers/dma/imx-dma.c b/drivers/dma/imx-dma.c
index ab0fb80..f681df8 100644
--- a/drivers/dma/imx-dma.c
+++ b/drivers/dma/imx-dma.c
@@ -888,7 +888,7 @@ static struct dma_async_tx_descriptor *imxdma_prep_dma_cyclic(
 	sg_init_table(imxdmac->sg_list, periods);
 
 	for (i = 0; i < periods; i++) {
-		imxdmac->sg_list[i].page_link = 0;
+		sg_assign_page(&imxdmac->sg_list[i], NULL);
 		imxdmac->sg_list[i].offset = 0;
 		imxdmac->sg_list[i].dma_address = dma_addr;
 		sg_dma_len(&imxdmac->sg_list[i]) = period_len;
@@ -896,10 +896,7 @@ static struct dma_async_tx_descriptor *imxdma_prep_dma_cyclic(
 	}
 
 	/* close the loop */
-	imxdmac->sg_list[periods].offset = 0;
-	sg_dma_len(&imxdmac->sg_list[periods]) = 0;
-	imxdmac->sg_list[periods].page_link =
-		((unsigned long)imxdmac->sg_list | 0x01) & ~0x02;
+	sg_chain(imxdmac->sg_list, periods + 1, imxdmac->sg_list);
 
 	desc->type = IMXDMA_DESC_CYCLIC;
 	desc->sg = imxdmac->sg_list;
diff --git a/drivers/dma/ste_dma40.c b/drivers/dma/ste_dma40.c
index a6620b6..c3052fb 100644
--- a/drivers/dma/ste_dma40.c
+++ b/drivers/dma/ste_dma40.c
@@ -2528,10 +2528,7 @@ dma40_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t dma_addr,
 		dma_addr += period_len;
 	}
 
-	sg[periods].offset = 0;
-	sg_dma_len(&sg[periods]) = 0;
-	sg[periods].page_link =
-		((unsigned long)sg | 0x01) & ~0x02;
+	sg_chain(sg, periods + 1, sg);
 
 	txd = d40_prep_sg(chan, sg, sg, periods, direction,
 			  DMA_PREP_INTERRUPT);
-- 
2.1.4