scatterlist cleanups

scatterlist cleanups

[Christoph Hellwig]

This series contains various scatterlist cleanups.  It makes the chained
scatterlist helpers generally available, even if a architecture doesn't
allow a DMA mapping for it, and changes two callers to make use of this
as well as cleans up various opencoded access to scatterlist internals.

A large part of this work is based on older patches from Dan.

[PATCH 1/6] scatterlist: allow limited chaining without ARCH_HAS_SG_CHAIN

[Christoph Hellwig]

There are a couple of uses of struct scatterlist that never go to
the dma_map_sg() helper and thus don't care about ARCH_HAS_SG_CHAIN
which indicates that we can map chained S/G list.

The most important one is the crypto code, which currently has
to open code a few helpers to always allow chaining.  This patch
removes a few #ifdef ARCH_HAS_SG_CHAIN statements so that we can
switch the crypto code to these common helpers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/scatterlist.h | 4 ----
 lib/scatterlist.c           | 4 ----
 2 files changed, 8 deletions(-)

diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index 9b1ef0c..698e906 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -161,10 +161,6 @@ static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
 static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
 			    struct scatterlist *sgl)
 {
-#ifndef CONFIG_ARCH_HAS_SG_CHAIN
-	BUG();
-#endif
-
 	/*
 	 * offset and length are unused for chain entry.  Clear them.
 	 */
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index d105a9f..bafa993 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -105,16 +105,12 @@ EXPORT_SYMBOL(sg_nents_for_len);
  **/
 struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents)
 {
-#ifndef CONFIG_ARCH_HAS_SG_CHAIN
-	struct scatterlist *ret = &sgl[nents - 1];
-#else
 	struct scatterlist *sg, *ret = NULL;
 	unsigned int i;
 
 	for_each_sg(sgl, sg, nents, i)
 		ret = sg;
 
-#endif
 #ifdef CONFIG_DEBUG_SG
 	BUG_ON(sgl[0].sg_magic != SG_MAGIC);
 	BUG_ON(!sg_is_last(ret));
-- 
1.9.1

[PATCH 2/6] target/rd: always chain S/G list

[Christoph Hellwig]

The rd sg lists are never passed to hardware, so use S/G chaining
unonditionally.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/target/target_core_rd.c | 44 -----------------------------------------
 1 file changed, 44 deletions(-)

diff --git a/drivers/target/target_core_rd.c b/drivers/target/target_core_rd.c
index 4703f40..badd927 100644
--- a/drivers/target/target_core_rd.c
+++ b/drivers/target/target_core_rd.c
@@ -138,16 +138,12 @@ static int rd_allocate_sgl_table(struct rd_dev *rd_dev, struct rd_dev_sg_table *
 		sg_per_table = (total_sg_needed > max_sg_per_table) ?
 			max_sg_per_table : total_sg_needed;
 
-#ifdef CONFIG_ARCH_HAS_SG_CHAIN
-
 		/*
 		 * Reserve extra element for chain entry
 		 */
 		if (sg_per_table < total_sg_needed)
 			chain_entry = 1;
 
-#endif /* CONFIG_ARCH_HAS_SG_CHAIN */
-
 		sg = kcalloc(sg_per_table + chain_entry, sizeof(*sg),
 				GFP_KERNEL);
 		if (!sg) {
@@ -158,15 +154,11 @@ static int rd_allocate_sgl_table(struct rd_dev *rd_dev, struct rd_dev_sg_table *
 
 		sg_init_table(sg, sg_per_table + chain_entry);
 
-#ifdef CONFIG_ARCH_HAS_SG_CHAIN
-
 		if (i > 0) {
 			sg_chain(sg_table[i - 1].sg_table,
 				 max_sg_per_table + 1, sg);
 		}
 
-#endif /* CONFIG_ARCH_HAS_SG_CHAIN */
-
 		sg_table[i].sg_table = sg;
 		sg_table[i].rd_sg_count = sg_per_table;
 		sg_table[i].page_start_offset = page_offset;
@@ -429,42 +421,6 @@ static sense_reason_t rd_do_prot_rw(struct se_cmd *cmd, bool is_read)
 	prot_sg = &prot_table->sg_table[prot_page -
 					prot_table->page_start_offset];
 
-#ifndef CONFIG_ARCH_HAS_SG_CHAIN
-
-	prot_npages = DIV_ROUND_UP(prot_offset + sectors * se_dev->prot_length,
-				   PAGE_SIZE);
-
-	/*
-	 * Allocate temporaly contiguous scatterlist entries if prot pages
-	 * straddles multiple scatterlist tables.
-	 */
-	if (prot_table->page_end_offset < prot_page + prot_npages - 1) {
-		int i;
-
-		prot_sg = kcalloc(prot_npages, sizeof(*prot_sg), GFP_KERNEL);
-		if (!prot_sg)
-			return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
-
-		need_to_release = true;
-		sg_init_table(prot_sg, prot_npages);
-
-		for (i = 0; i < prot_npages; i++) {
-			if (prot_page + i > prot_table->page_end_offset) {
-				prot_table = rd_get_prot_table(dev,
-								prot_page + i);
-				if (!prot_table) {
-					kfree(prot_sg);
-					return rc;
-				}
-				sg_unmark_end(&prot_sg[i - 1]);
-			}
-			prot_sg[i] = prot_table->sg_table[prot_page + i -
-						prot_table->page_start_offset];
-		}
-	}
-
-#endif /* !CONFIG_ARCH_HAS_SG_CHAIN */
-
 	if (is_read)
 		rc = sbc_dif_verify(cmd, cmd->t_task_lba, sectors, 0,
 				    prot_sg, prot_offset);
-- 
1.9.1

[PATCH 3/6] crypto: replace scatterwalk_sg_chain with sg_chain

[Christoph Hellwig]

From: Dan Williams <dan.j.williams@intel.com>

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
[hch: split from a larger patch by Dan]
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 crypto/algif_skcipher.c      |  2 +-
 crypto/ccm.c                 |  8 ++++----
 crypto/gcm.c                 |  4 ++--
 drivers/crypto/bfin_crc.c    |  3 +--
 drivers/crypto/qce/sha.c     |  2 +-
 drivers/crypto/sahara.c      |  2 +-
 drivers/crypto/talitos.c     |  2 +-
 include/crypto/scatterwalk.h | 10 +---------
 8 files changed, 12 insertions(+), 21 deletions(-)

diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
index 9450752..af31a0e 100644
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -145,7 +145,7 @@ static int skcipher_alloc_sgl(struct sock *sk)
 		sgl->cur = 0;
 
 		if (sg)
-			scatterwalk_sg_chain(sg, MAX_SGL_ENTS + 1, sgl->sg);
+			sg_chain(sg, MAX_SGL_ENTS + 1, sgl->sg);
 
 		list_add_tail(&sgl->list, &ctx->tsgl);
 	}
diff --git a/crypto/ccm.c b/crypto/ccm.c
index a4d1a5e..b3f52f5 100644
--- a/crypto/ccm.c
+++ b/crypto/ccm.c
@@ -329,13 +329,13 @@ static int crypto_ccm_encrypt(struct aead_request *req)
 
 	sg_init_table(pctx->src, 2);
 	sg_set_buf(pctx->src, odata, 16);
-	scatterwalk_sg_chain(pctx->src, 2, req->src);
+	sg_chain(pctx->src, 2, req->src);
 
 	dst = pctx->src;
 	if (req->src != req->dst) {
 		sg_init_table(pctx->dst, 2);
 		sg_set_buf(pctx->dst, odata, 16);
-		scatterwalk_sg_chain(pctx->dst, 2, req->dst);
+		sg_chain(pctx->dst, 2, req->dst);
 		dst = pctx->dst;
 	}
 
@@ -400,13 +400,13 @@ static int crypto_ccm_decrypt(struct aead_request *req)
 
 	sg_init_table(pctx->src, 2);
 	sg_set_buf(pctx->src, authtag, 16);
-	scatterwalk_sg_chain(pctx->src, 2, req->src);
+	sg_chain(pctx->src, 2, req->src);
 
 	dst = pctx->src;
 	if (req->src != req->dst) {
 		sg_init_table(pctx->dst, 2);
 		sg_set_buf(pctx->dst, authtag, 16);
-		scatterwalk_sg_chain(pctx->dst, 2, req->dst);
+		sg_chain(pctx->dst, 2, req->dst);
 		dst = pctx->dst;
 	}
 
diff --git a/crypto/gcm.c b/crypto/gcm.c
index 7d32d47..ab0b2f9 100644
--- a/crypto/gcm.c
+++ b/crypto/gcm.c
@@ -200,14 +200,14 @@ static void crypto_gcm_init_common(struct aead_request *req)
 	sg_set_buf(pctx->src, pctx->auth_tag, sizeof(pctx->auth_tag));
 	sg = scatterwalk_ffwd(pctx->src + 1, req->src, req->assoclen);
 	if (sg != pctx->src + 1)
-		scatterwalk_sg_chain(pctx->src, 2, sg);
+		sg_chain(pctx->src, 2, sg);
 
 	if (req->src != req->dst) {
 		sg_init_table(pctx->dst, 3);
 		sg_set_buf(pctx->dst, pctx->auth_tag, sizeof(pctx->auth_tag));
 		sg = scatterwalk_ffwd(pctx->dst + 1, req->dst, req->assoclen);
 		if (sg != pctx->dst + 1)
-			scatterwalk_sg_chain(pctx->dst, 2, sg);
+			sg_chain(pctx->dst, 2, sg);
 	}
 }
 
diff --git a/drivers/crypto/bfin_crc.c b/drivers/crypto/bfin_crc.c
index d9af940..2f0b333 100644
--- a/drivers/crypto/bfin_crc.c
+++ b/drivers/crypto/bfin_crc.c
@@ -370,8 +370,7 @@ static int bfin_crypto_crc_handle_queue(struct bfin_crypto_crc *crc,
 			sg_init_table(ctx->bufsl, nsg);
 			sg_set_buf(ctx->bufsl, ctx->buflast, ctx->buflast_len);
 			if (nsg > 1)
-				scatterwalk_sg_chain(ctx->bufsl, nsg,
-						req->src);
+				sg_chain(ctx->bufsl, nsg, req->src);
 			ctx->sg = ctx->bufsl;
 		} else
 			ctx->sg = req->src;
diff --git a/drivers/crypto/qce/sha.c b/drivers/crypto/qce/sha.c
index 5c5df1d..be2f504 100644
--- a/drivers/crypto/qce/sha.c
+++ b/drivers/crypto/qce/sha.c
@@ -296,7 +296,7 @@ static int qce_ahash_update(struct ahash_request *req)
 	if (rctx->buflen) {
 		sg_init_table(rctx->sg, 2);
 		sg_set_buf(rctx->sg, rctx->tmpbuf, rctx->buflen);
-		scatterwalk_sg_chain(rctx->sg, 2, req->src);
+		sg_chain(rctx->sg, 2, req->src);
 		req->src = rctx->sg;
 	}
 
diff --git a/drivers/crypto/sahara.c b/drivers/crypto/sahara.c
index 397a500..a75cf66 100644
--- a/drivers/crypto/sahara.c
+++ b/drivers/crypto/sahara.c
@@ -999,7 +999,7 @@ static int sahara_sha_prepare_request(struct ahash_request *req)
 		sg_init_table(rctx->in_sg_chain, 2);
 		sg_set_buf(rctx->in_sg_chain, rctx->rembuf, rctx->buf_cnt);
 
-		scatterwalk_sg_chain(rctx->in_sg_chain, 2, req->src);
+		sg_chain(rctx->in_sg_chain, 2, req->src);
 
 		rctx->total = req->nbytes + rctx->buf_cnt;
 		rctx->in_sg = rctx->in_sg_chain;
diff --git a/drivers/crypto/talitos.c b/drivers/crypto/talitos.c
index 83aca95..6a7f024 100644
--- a/drivers/crypto/talitos.c
+++ b/drivers/crypto/talitos.c
@@ -1986,7 +1986,7 @@ static int ahash_process_req(struct ahash_request *areq, unsigned int nbytes)
 		sg_init_table(req_ctx->bufsl, nsg);
 		sg_set_buf(req_ctx->bufsl, req_ctx->buf, req_ctx->nbuf);
 		if (nsg > 1)
-			scatterwalk_sg_chain(req_ctx->bufsl, 2, areq->src);
+			sg_chain(req_ctx->bufsl, 2, areq->src);
 		req_ctx->psrc = req_ctx->bufsl;
 	} else
 		req_ctx->psrc = areq->src;
diff --git a/include/crypto/scatterwalk.h b/include/crypto/scatterwalk.h
index 96670e7..35f99b6 100644
--- a/include/crypto/scatterwalk.h
+++ b/include/crypto/scatterwalk.h
@@ -25,14 +25,6 @@
 #include <linux/scatterlist.h>
 #include <linux/sched.h>
 
-static inline void scatterwalk_sg_chain(struct scatterlist *sg1, int num,
-					struct scatterlist *sg2)
-{
-	sg_set_page(&sg1[num - 1], (void *)sg2, 0, 0);
-	sg1[num - 1].page_link &= ~0x02;
-	sg1[num - 1].page_link |= 0x01;
-}
-
 static inline void scatterwalk_crypto_chain(struct scatterlist *head,
 					    struct scatterlist *sg,
 					    int chain, int num)
@@ -43,7 +35,7 @@ static inline void scatterwalk_crypto_chain(struct scatterlist *head,
 	}
 
 	if (sg)
-		scatterwalk_sg_chain(head, num, sg);
+		sg_chain(head, num, sg);
 	else
 		sg_mark_end(head);
 }
-- 
1.9.1

[PATCH 4/6] scatterlist: remove open coded sg_unmark_end instances

[Christoph Hellwig]

From: Dan Williams <dan.j.williams@intel.com>

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
[hch: split from a larger patch by Dan]
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-merge.c        | 2 +-
 drivers/mmc/card/queue.c | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/block/blk-merge.c b/block/blk-merge.c
index 30a0d9f..f4a3e87 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -266,7 +266,7 @@ int blk_rq_map_sg(struct request_queue *q, struct request *rq,
 		if (rq->cmd_flags & REQ_WRITE)
 			memset(q->dma_drain_buffer, 0, q->dma_drain_size);
 
-		sg->page_link &= ~0x02;
+		sg_unmark_end(sg);
 		sg = sg_next(sg);
 		sg_set_page(sg, virt_to_page(q->dma_drain_buffer),
 			    q->dma_drain_size,
diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
index b5a2b14..9b214da 100644
--- a/drivers/mmc/card/queue.c
+++ b/drivers/mmc/card/queue.c
@@ -467,7 +467,7 @@ static unsigned int mmc_queue_packed_map_sg(struct mmc_queue *mq,
 			sg_set_buf(__sg, buf + offset, len);
 			offset += len;
 			remain -= len;
-			(__sg++)->page_link &= ~0x02;
+			sg_unmark_end(__sg++);
 			sg_len++;
 		} while (remain);
 	}
@@ -475,7 +475,7 @@ static unsigned int mmc_queue_packed_map_sg(struct mmc_queue *mq,
 	list_for_each_entry(req, &packed->list, queuelist) {
 		sg_len += blk_rq_map_sg(mq->queue, req, __sg);
 		__sg = sg + (sg_len - 1);
-		(__sg++)->page_link &= ~0x02;
+		sg_unmark_end(__sg++);
 	}
 	sg_mark_end(sg + (sg_len - 1));
 	return sg_len;
-- 
1.9.1

[PATCH 5/6] crypto/omap-sham: remove an open coded access to ->page_link

[Christoph Hellwig]

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
[hch: split from a larger patch by Dan]
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/crypto/omap-sham.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/crypto/omap-sham.c b/drivers/crypto/omap-sham.c
index b2024c95..48adb2a 100644
--- a/drivers/crypto/omap-sham.c
+++ b/drivers/crypto/omap-sham.c
@@ -588,7 +588,7 @@ static int omap_sham_xmit_dma(struct omap_sham_dev *dd, dma_addr_t dma_addr,
 		 * the dmaengine may try to DMA the incorrect amount of data.
 		 */
 		sg_init_table(&ctx->sgl, 1);
-		ctx->sgl.page_link = ctx->sg->page_link;
+		sg_assign_page(&ctx->sgl, sg_page(ctx->sg));
 		ctx->sgl.offset = ctx->sg->offset;
 		sg_dma_len(&ctx->sgl) = len32;
 		sg_dma_address(&ctx->sgl) = sg_dma_address(ctx->sg);
-- 
1.9.1

[PATCH 6/6] scatterlist: use sg_phys()

[Christoph Hellwig]

From: Dan Williams <dan.j.williams@intel.com>

Coccinelle cleanup to replace open coded sg to physical address
translations.  This is in preparation for introducing scatterlists that
reference __pfn_t.

// sg_phys.cocci: convert usage page_to_phys(sg_page(sg)) to sg_phys(sg)
// usage: make coccicheck COCCI=sg_phys.cocci MODE=patch

virtual patch
virtual report
virtual org

@@
struct scatterlist *sg;
@@

- page_to_phys(sg_page(sg)) + sg->offset
+ sg_phys(sg)

@@
struct scatterlist *sg;
@@

- page_to_phys(sg_page(sg))
+ sg_phys(sg) - sg->offset

Cc: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 arch/arm/mm/dma-mapping.c                    | 2 +-
 arch/microblaze/kernel/dma.c                 | 2 +-
 drivers/iommu/intel-iommu.c                  | 4 ++--
 drivers/iommu/iommu.c                        | 2 +-
 drivers/staging/android/ion/ion_chunk_heap.c | 4 ++--
 5 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index cba12f3..58774b9 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1520,7 +1520,7 @@ static int __map_sg_chunk(struct device *dev, struct scatterlist *sg,
 		return -ENOMEM;
 
 	for (count = 0, s = sg; count < (size >> PAGE_SHIFT); s = sg_next(s)) {
-		phys_addr_t phys = page_to_phys(sg_page(s));
+		phys_addr_t phys = sg_phys(s) - s->offset;
 		unsigned int len = PAGE_ALIGN(s->offset + s->length);
 
 		if (!is_coherent &&
diff --git a/arch/microblaze/kernel/dma.c b/arch/microblaze/kernel/dma.c
index bf4dec2..9c8e8f4 100644
--- a/arch/microblaze/kernel/dma.c
+++ b/arch/microblaze/kernel/dma.c
@@ -61,7 +61,7 @@ static int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl,
 	/* FIXME this part of code is untested */
 	for_each_sg(sgl, sg, nents, i) {
 		sg->dma_address = sg_phys(sg);
-		__dma_sync(page_to_phys(sg_page(sg)) + sg->offset,
+		__dma_sync(sg_phys(sg),
 							sg->length, direction);
 	}
 
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 5852df8..e0faecc 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -2098,7 +2098,7 @@ static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
 			sg_res = aligned_nrpages(sg->offset, sg->length);
 			sg->dma_address = ((dma_addr_t)iov_pfn << VTD_PAGE_SHIFT) + sg->offset;
 			sg->dma_length = sg->length;
-			pteval = page_to_phys(sg_page(sg)) | prot;
+			pteval = (sg_phys(sg) - sg->offset) | prot;
 			phys_pfn = pteval >> VTD_PAGE_SHIFT;
 		}
 
@@ -3625,7 +3625,7 @@ static int intel_nontranslate_map_sg(struct device *hddev,
 
 	for_each_sg(sglist, sg, nelems, i) {
 		BUG_ON(!sg_page(sg));
-		sg->dma_address = page_to_phys(sg_page(sg)) + sg->offset;
+		sg->dma_address = sg_phys(sg);
 		sg->dma_length = sg->length;
 	}
 	return nelems;
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index f286090..049df49 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1408,7 +1408,7 @@ size_t default_iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
 	min_pagesz = 1 << __ffs(domain->ops->pgsize_bitmap);
 
 	for_each_sg(sg, s, nents, i) {
-		phys_addr_t phys = page_to_phys(sg_page(s)) + s->offset;
+		phys_addr_t phys = sg_phys(s);
 
 		/*
 		 * We are mapping on IOMMU page boundaries, so offset within
diff --git a/drivers/staging/android/ion/ion_chunk_heap.c b/drivers/staging/android/ion/ion_chunk_heap.c
index 5474615..c422006 100644
--- a/drivers/staging/android/ion/ion_chunk_heap.c
+++ b/drivers/staging/android/ion/ion_chunk_heap.c
@@ -81,7 +81,7 @@ static int ion_chunk_heap_allocate(struct ion_heap *heap,
 err:
 	sg = table->sgl;
 	for (i -= 1; i >= 0; i--) {
-		gen_pool_free(chunk_heap->pool, page_to_phys(sg_page(sg)),
+		gen_pool_free(chunk_heap->pool, sg_phys(sg) - sg->offset,
 			      sg->length);
 		sg = sg_next(sg);
 	}
@@ -109,7 +109,7 @@ static void ion_chunk_heap_free(struct ion_buffer *buffer)
 							DMA_BIDIRECTIONAL);
 
 	for_each_sg(table->sgl, sg, table->nents, i) {
-		gen_pool_free(chunk_heap->pool, page_to_phys(sg_page(sg)),
+		gen_pool_free(chunk_heap->pool, sg_phys(sg) - sg->offset,
 			      sg->length);
 	}
 	chunk_heap->allocated -= allocated_size;
-- 
1.9.1

Re: [PATCH 6/6] scatterlist: use sg_phys()

[Dan Williams]

On Fri, Aug 7, 2015 at 9:15 AM, Christoph Hellwig <hch@lst.de> wrote:
> From: Dan Williams <dan.j.williams@intel.com>
>
> Coccinelle cleanup to replace open coded sg to physical address
> translations.  This is in preparation for introducing scatterlists that
> reference __pfn_t.
>
> // sg_phys.cocci: convert usage page_to_phys(sg_page(sg)) to sg_phys(sg)
> // usage: make coccicheck COCCI=sg_phys.cocci MODE=patch
>
> virtual patch
> virtual report
> virtual org
>
> @@
> struct scatterlist *sg;
> @@
>
> - page_to_phys(sg_page(sg)) + sg->offset
> + sg_phys(sg)
>
> @@
> struct scatterlist *sg;
> @@
>
> - page_to_phys(sg_page(sg))
> + sg_phys(sg) - sg->offset

So this ends up being an awkward conversion, a better one is:

- page_to_phys(sg_page(sg))
+ sg_phys(sg) & PAGE_MASK

[..]
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 5852df8..e0faecc 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -2098,7 +2098,7 @@ static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
>                         sg_res = aligned_nrpages(sg->offset, sg->length);
>                         sg->dma_address = ((dma_addr_t)iov_pfn << VTD_PAGE_SHIFT) + sg->offset;
>                         sg->dma_length = sg->length;
> -                       pteval = page_to_phys(sg_page(sg)) | prot;
> +                       pteval = (sg_phys(sg) - sg->offset) | prot;

For example here, as Joerg pointed out.

[1]: https://lkml.org/lkml/2015/6/10/230

Re: [PATCH 6/6] scatterlist: use sg_phys()

[Williams, Dan J]

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On Fri, 2015-08-07 at 18:15 +0200, Christoph Hellwig wrote:
[..]
> - page_to_phys(sg_page(sg))
> + sg_phys(sg) - sg->offset

Here's a replacement using PAGE_MASK instead of subtracting sg->offset
and a fixup for the awkward whitespace in dma_direct_map_sg().

8<-----
Subject: scatterlist: use sg_phys()

From: Dan Williams <dan.j.williams@intel.com>

Coccinelle cleanup to replace open coded sg to physical address
translations.  This is in preparation for introducing scatterlists that
reference __pfn_t.

// sg_phys.cocci: convert usage page_to_phys(sg_page(sg)) to sg_phys(sg)
// usage: make coccicheck COCCI=sg_phys.cocci MODE=patch

virtual patch

@@
struct scatterlist *sg;
@@

- page_to_phys(sg_page(sg)) + sg->offset
+ sg_phys(sg)

@@
struct scatterlist *sg;
@@

- page_to_phys(sg_page(sg))
+ sg_phys(sg) & PAGE_MASK

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 arch/arm/mm/dma-mapping.c                    |    2 +-
 arch/microblaze/kernel/dma.c                 |    3 +--
 drivers/iommu/intel-iommu.c                  |    4 ++--
 drivers/iommu/iommu.c                        |    2 +-
 drivers/staging/android/ion/ion_chunk_heap.c |    4 ++--
 5 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index cba12f34ff77..3d3d6aa60c87 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1520,7 +1520,7 @@ static int __map_sg_chunk(struct device *dev, struct scatterlist *sg,
 		return -ENOMEM;
 
 	for (count = 0, s = sg; count < (size >> PAGE_SHIFT); s = sg_next(s)) {
-		phys_addr_t phys = page_to_phys(sg_page(s));
+		phys_addr_t phys = sg_phys(s) & PAGE_MASK;
 		unsigned int len = PAGE_ALIGN(s->offset + s->length);
 
 		if (!is_coherent &&
diff --git a/arch/microblaze/kernel/dma.c b/arch/microblaze/kernel/dma.c
index bf4dec229437..c89da6312954 100644
--- a/arch/microblaze/kernel/dma.c
+++ b/arch/microblaze/kernel/dma.c
@@ -61,8 +61,7 @@ static int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl,
 	/* FIXME this part of code is untested */
 	for_each_sg(sgl, sg, nents, i) {
 		sg->dma_address = sg_phys(sg);
-		__dma_sync(page_to_phys(sg_page(sg)) + sg->offset,
-							sg->length, direction);
+		__dma_sync(sg_phys(sg), sg->length, direction);
 	}
 
 	return nents;
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 5852df8cc50f..7b6c5b63ece7 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -2098,7 +2098,7 @@ static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
 			sg_res = aligned_nrpages(sg->offset, sg->length);
 			sg->dma_address = ((dma_addr_t)iov_pfn << VTD_PAGE_SHIFT) + sg->offset;
 			sg->dma_length = sg->length;
-			pteval = page_to_phys(sg_page(sg)) | prot;
+			pteval = (sg_phys(sg) & PAGE_MASK) | prot;
 			phys_pfn = pteval >> VTD_PAGE_SHIFT;
 		}
 
@@ -3625,7 +3625,7 @@ static int intel_nontranslate_map_sg(struct device *hddev,
 
 	for_each_sg(sglist, sg, nelems, i) {
 		BUG_ON(!sg_page(sg));
-		sg->dma_address = page_to_phys(sg_page(sg)) + sg->offset;
+		sg->dma_address = sg_phys(sg);
 		sg->dma_length = sg->length;
 	}
 	return nelems;
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index f286090931cc..049df495c274 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1408,7 +1408,7 @@ size_t default_iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
 	min_pagesz = 1 << __ffs(domain->ops->pgsize_bitmap);
 
 	for_each_sg(sg, s, nents, i) {
-		phys_addr_t phys = page_to_phys(sg_page(s)) + s->offset;
+		phys_addr_t phys = sg_phys(s);
 
 		/*
 		 * We are mapping on IOMMU page boundaries, so offset within
diff --git a/drivers/staging/android/ion/ion_chunk_heap.c b/drivers/staging/android/ion/ion_chunk_heap.c
index 54746157d799..f7b6ef991cd0 100644
--- a/drivers/staging/android/ion/ion_chunk_heap.c
+++ b/drivers/staging/android/ion/ion_chunk_heap.c
@@ -81,7 +81,7 @@ static int ion_chunk_heap_allocate(struct ion_heap *heap,
 err:
 	sg = table->sgl;
 	for (i -= 1; i >= 0; i--) {
-		gen_pool_free(chunk_heap->pool, page_to_phys(sg_page(sg)),
+		gen_pool_free(chunk_heap->pool, sg_phys(sg) & PAGE_MASK,
 			      sg->length);
 		sg = sg_next(sg);
 	}
@@ -109,7 +109,7 @@ static void ion_chunk_heap_free(struct ion_buffer *buffer)
 							DMA_BIDIRECTIONAL);
 
 	for_each_sg(table->sgl, sg, table->nents, i) {
-		gen_pool_free(chunk_heap->pool, page_to_phys(sg_page(sg)),
+		gen_pool_free(chunk_heap->pool, sg_phys(sg) & PAGE_MASK,
 			      sg->length);
 	}
 	chunk_heap->allocated -= allocated_size;

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Re: [PATCH 3/6] crypto: replace scatterwalk_sg_chain with sg_chain

[Herbert Xu]

On Fri, Aug 07, 2015 at 06:15:13PM +0200, Christoph Hellwig wrote:
> From: Dan Williams <dan.j.williams@intel.com>
> 
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> [hch: split from a larger patch by Dan]
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: [PATCH 5/6] crypto/omap-sham: remove an open coded access to ->page_link

[Herbert Xu]

On Fri, Aug 07, 2015 at 06:15:15PM +0200, Christoph Hellwig wrote:
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> [hch: split from a larger patch by Dan]
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt