[PATCH v6 26/36] drm: rcar-du: fix common struct sg_table related issues

[PATCH v6 26/36] drm: rcar-du: fix common struct sg_table related issues

[Marek Szyprowski]

The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function
returns the number of the created entries in the DMA address space.
However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and
dma_unmap_sg must be called with the original number of the entries
passed to the dma_map_sg().

struct sg_table is a common structure used for describing a non-contiguous
memory buffer, used commonly in the DRM and graphics subsystems. It
consists of a scatterlist with memory pages and DMA addresses (sgl entry),
as well as the number of scatterlist entries: CPU pages (orig_nents entry)
and DMA mapped pages (nents entry).

It turned out that it was a common mistake to misuse nents and orig_nents
entries, calling DMA-mapping functions with a wrong number of entries or
ignoring the number of mapped entries returned by the dma_map_sg()
function.

To avoid such issues, lets use a common dma-mapping wrappers operating
directly on the struct sg_table objects and use scatterlist page
iterators where possible. This, almost always, hides references to the
nents and orig_nents entries, making the code robust, easier to follow
and copy/paste safe.

dma_map_sgtable() function returns zero or an error code, so adjust the
return value check for the vsp1_du_map_sg() function.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/gpu/drm/rcar-du/rcar_du_vsp.c  | 3 +--
 drivers/media/platform/vsp1/vsp1_drm.c | 8 ++++----
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/rcar-du/rcar_du_vsp.c b/drivers/gpu/drm/rcar-du/rcar_du_vsp.c
index f1a81c9b184d..a27bff999649 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_vsp.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_vsp.c
@@ -197,9 +197,8 @@ int rcar_du_vsp_map_fb(struct rcar_du_vsp *vsp, struct drm_framebuffer *fb,
 			goto fail;
 
 		ret = vsp1_du_map_sg(vsp->vsp, sgt);
-		if (!ret) {
+		if (ret) {
 			sg_free_table(sgt);
-			ret = -ENOMEM;
 			goto fail;
 		}
 	}
diff --git a/drivers/media/platform/vsp1/vsp1_drm.c b/drivers/media/platform/vsp1/vsp1_drm.c
index a4a45d68a6ef..86d5e3f4b1ff 100644
--- a/drivers/media/platform/vsp1/vsp1_drm.c
+++ b/drivers/media/platform/vsp1/vsp1_drm.c
@@ -912,8 +912,8 @@ int vsp1_du_map_sg(struct device *dev, struct sg_table *sgt)
 	 * skip cache sync. This will need to be revisited when support for
 	 * non-coherent buffers will be added to the DU driver.
 	 */
-	return dma_map_sg_attrs(vsp1->bus_master, sgt->sgl, sgt->nents,
-				DMA_TO_DEVICE, DMA_ATTR_SKIP_CPU_SYNC);
+	return dma_map_sgtable(vsp1->bus_master, sgt, DMA_TO_DEVICE,
+			       DMA_ATTR_SKIP_CPU_SYNC);
 }
 EXPORT_SYMBOL_GPL(vsp1_du_map_sg);
 
@@ -921,8 +921,8 @@ void vsp1_du_unmap_sg(struct device *dev, struct sg_table *sgt)
 {
 	struct vsp1_device *vsp1 = dev_get_drvdata(dev);
 
-	dma_unmap_sg_attrs(vsp1->bus_master, sgt->sgl, sgt->nents,
-			   DMA_TO_DEVICE, DMA_ATTR_SKIP_CPU_SYNC);
+	dma_unmap_sgtable(vsp1->bus_master, sgt, DMA_TO_DEVICE,
+			  DMA_ATTR_SKIP_CPU_SYNC);
 }
 EXPORT_SYMBOL_GPL(vsp1_du_unmap_sg);
 
-- 
2.17.1

[PATCH v6 27/36] dmabuf: fix common struct sg_table related issues

[Marek Szyprowski]

The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function
returns the number of the created entries in the DMA address space.
However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and
dma_unmap_sg must be called with the original number of the entries
passed to the dma_map_sg().

struct sg_table is a common structure used for describing a non-contiguous
memory buffer, used commonly in the DRM and graphics subsystems. It
consists of a scatterlist with memory pages and DMA addresses (sgl entry),
as well as the number of scatterlist entries: CPU pages (orig_nents entry)
and DMA mapped pages (nents entry).

It turned out that it was a common mistake to misuse nents and orig_nents
entries, calling DMA-mapping functions with a wrong number of entries or
ignoring the number of mapped entries returned by the dma_map_sg()
function.

To avoid such issues, lets use a common dma-mapping wrappers operating
directly on the struct sg_table objects and use scatterlist page
iterators where possible. This, almost always, hides references to the
nents and orig_nents entries, making the code robust, easier to follow
and copy/paste safe.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
---
 drivers/dma-buf/heaps/heap-helpers.c | 13 ++++++-------
 drivers/dma-buf/udmabuf.c            |  7 +++----
 2 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/drivers/dma-buf/heaps/heap-helpers.c b/drivers/dma-buf/heaps/heap-helpers.c
index 9f964ca3f59c..d0696cf937af 100644
--- a/drivers/dma-buf/heaps/heap-helpers.c
+++ b/drivers/dma-buf/heaps/heap-helpers.c
@@ -140,13 +140,12 @@ struct sg_table *dma_heap_map_dma_buf(struct dma_buf_attachment *attachment,
 				      enum dma_data_direction direction)
 {
 	struct dma_heaps_attachment *a = attachment->priv;
-	struct sg_table *table;
-
-	table = &a->table;
+	struct sg_table *table = &a->table;
+	int ret;
 
-	if (!dma_map_sg(attachment->dev, table->sgl, table->nents,
-			direction))
-		table = ERR_PTR(-ENOMEM);
+	ret = dma_map_sgtable(attachment->dev, table, direction, 0);
+	if (ret)
+		table = ERR_PTR(ret);
 	return table;
 }
 
@@ -154,7 +153,7 @@ static void dma_heap_unmap_dma_buf(struct dma_buf_attachment *attachment,
 				   struct sg_table *table,
 				   enum dma_data_direction direction)
 {
-	dma_unmap_sg(attachment->dev, table->sgl, table->nents, direction);
+	dma_unmap_sgtable(attachment->dev, table, direction, 0);
 }
 
 static vm_fault_t dma_heap_vm_fault(struct vm_fault *vmf)
diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
index acb26c627d27..89e293bd9252 100644
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -63,10 +63,9 @@ static struct sg_table *get_sg_table(struct device *dev, struct dma_buf *buf,
 					GFP_KERNEL);
 	if (ret < 0)
 		goto err;
-	if (!dma_map_sg(dev, sg->sgl, sg->nents, direction)) {
-		ret = -EINVAL;
+	ret = dma_map_sgtable(dev, sg, direction, 0);
+	if (ret < 0)
 		goto err;
-	}
 	return sg;
 
 err:
@@ -78,7 +77,7 @@ static struct sg_table *get_sg_table(struct device *dev, struct dma_buf *buf,
 static void put_sg_table(struct device *dev, struct sg_table *sg,
 			 enum dma_data_direction direction)
 {
-	dma_unmap_sg(dev, sg->sgl, sg->nents, direction);
+	dma_unmap_sgtable(dev, sg, direction, 0);
 	sg_free_table(sg);
 	kfree(sg);
 }
-- 
2.17.1

[PATCH v6 30/36] staging: tegra-vde: fix common struct sg_table related issues

[Marek Szyprowski]

The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function
returns the number of the created entries in the DMA address space.
However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and
dma_unmap_sg must be called with the original number of the entries
passed to the dma_map_sg().

struct sg_table is a common structure used for describing a non-contiguous
memory buffer, used commonly in the DRM and graphics subsystems. It
consists of a scatterlist with memory pages and DMA addresses (sgl entry),
as well as the number of scatterlist entries: CPU pages (orig_nents entry)
and DMA mapped pages (nents entry).

It turned out that it was a common mistake to misuse nents and orig_nents
entries, calling DMA-mapping functions with a wrong number of entries or
ignoring the number of mapped entries returned by the dma_map_sg()
function.

To avoid such issues, lets use a common dma-mapping wrappers operating
directly on the struct sg_table objects and use scatterlist page
iterators where possible. This, almost always, hides references to the
nents and orig_nents entries, making the code robust, easier to follow
and copy/paste safe.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/staging/media/tegra-vde/iommu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/media/tegra-vde/iommu.c b/drivers/staging/media/tegra-vde/iommu.c
index 6af863d92123..adf8dc7ee25c 100644
--- a/drivers/staging/media/tegra-vde/iommu.c
+++ b/drivers/staging/media/tegra-vde/iommu.c
@@ -36,8 +36,8 @@ int tegra_vde_iommu_map(struct tegra_vde *vde,
 
 	addr = iova_dma_addr(&vde->iova, iova);
 
-	size = iommu_map_sg(vde->domain, addr, sgt->sgl, sgt->nents,
-			    IOMMU_READ | IOMMU_WRITE);
+	size = iommu_map_sgtable(vde->domain, addr, sgt,
+				 IOMMU_READ | IOMMU_WRITE);
 	if (!size) {
 		__free_iova(&vde->iova, iova);
 		return -ENXIO;
-- 
2.17.1

[PATCH v6 34/36] media: pci: fix common ALSA DMA-mapping related codes

[Marek Szyprowski]

The Documentation/DMA-API-HOWTO.txt states that dma_map_sg returns the
numer of the created entries in the DMA address space. However the
subsequent calls to dma_sync_sg_for_{device,cpu} and dma_unmap_sg must be
called with the original number of entries passed to dma_map_sg. The
sg_table->nents in turn holds the result of the dma_map_sg call as stated
in include/linux/scatterlist.h. Adapt the code to obey those rules.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
---
 drivers/media/pci/cx23885/cx23885-alsa.c | 2 +-
 drivers/media/pci/cx25821/cx25821-alsa.c | 2 +-
 drivers/media/pci/cx88/cx88-alsa.c       | 2 +-
 drivers/media/pci/saa7134/saa7134-alsa.c | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/media/pci/cx23885/cx23885-alsa.c b/drivers/media/pci/cx23885/cx23885-alsa.c
index df44ed7393a0..3f366e4e4685 100644
--- a/drivers/media/pci/cx23885/cx23885-alsa.c
+++ b/drivers/media/pci/cx23885/cx23885-alsa.c
@@ -129,7 +129,7 @@ static int cx23885_alsa_dma_unmap(struct cx23885_audio_dev *dev)
 	if (!buf->sglen)
 		return 0;
 
-	dma_unmap_sg(&dev->pci->dev, buf->sglist, buf->sglen, PCI_DMA_FROMDEVICE);
+	dma_unmap_sg(&dev->pci->dev, buf->sglist, buf->nr_pages, PCI_DMA_FROMDEVICE);
 	buf->sglen = 0;
 	return 0;
 }
diff --git a/drivers/media/pci/cx25821/cx25821-alsa.c b/drivers/media/pci/cx25821/cx25821-alsa.c
index 301616426d8a..c40304d33776 100644
--- a/drivers/media/pci/cx25821/cx25821-alsa.c
+++ b/drivers/media/pci/cx25821/cx25821-alsa.c
@@ -193,7 +193,7 @@ static int cx25821_alsa_dma_unmap(struct cx25821_audio_dev *dev)
 	if (!buf->sglen)
 		return 0;
 
-	dma_unmap_sg(&dev->pci->dev, buf->sglist, buf->sglen, PCI_DMA_FROMDEVICE);
+	dma_unmap_sg(&dev->pci->dev, buf->sglist, buf->nr_pages, PCI_DMA_FROMDEVICE);
 	buf->sglen = 0;
 	return 0;
 }
diff --git a/drivers/media/pci/cx88/cx88-alsa.c b/drivers/media/pci/cx88/cx88-alsa.c
index 7d7aceecc985..3c6fe6ceb0b7 100644
--- a/drivers/media/pci/cx88/cx88-alsa.c
+++ b/drivers/media/pci/cx88/cx88-alsa.c
@@ -332,7 +332,7 @@ static int cx88_alsa_dma_unmap(struct cx88_audio_dev *dev)
 	if (!buf->sglen)
 		return 0;
 
-	dma_unmap_sg(&dev->pci->dev, buf->sglist, buf->sglen,
+	dma_unmap_sg(&dev->pci->dev, buf->sglist, buf->nr_pages,
 		     PCI_DMA_FROMDEVICE);
 	buf->sglen = 0;
 	return 0;
diff --git a/drivers/media/pci/saa7134/saa7134-alsa.c b/drivers/media/pci/saa7134/saa7134-alsa.c
index 544ca57eee75..398c47ff473d 100644
--- a/drivers/media/pci/saa7134/saa7134-alsa.c
+++ b/drivers/media/pci/saa7134/saa7134-alsa.c
@@ -313,7 +313,7 @@ static int saa7134_alsa_dma_unmap(struct saa7134_dev *dev)
 	if (!dma->sglen)
 		return 0;
 
-	dma_unmap_sg(&dev->pci->dev, dma->sglist, dma->sglen, PCI_DMA_FROMDEVICE);
+	dma_unmap_sg(&dev->pci->dev, dma->sglist, dma->nr_pages, PCI_DMA_FROMDEVICE);
 	dma->sglen = 0;
 	return 0;
 }
-- 
2.17.1

[PATCH v6 35/36] videobuf2: use sgtable-based scatterlist wrappers

[Marek Szyprowski]

Use recently introduced common wrappers operating directly on the struct
sg_table objects and scatterlist page iterators to make the code a bit
more compact, robust, easier to follow and copy/paste safe.

No functional change, because the code already properly did all the
scaterlist related calls.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
---
 .../common/videobuf2/videobuf2-dma-contig.c   | 41 ++++++++-----------
 .../media/common/videobuf2/videobuf2-dma-sg.c | 32 ++++++---------
 .../common/videobuf2/videobuf2-vmalloc.c      | 12 ++----
 3 files changed, 34 insertions(+), 51 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-dma-contig.c b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
index f4b4a7c135eb..ba01a8692d88 100644
--- a/drivers/media/common/videobuf2/videobuf2-dma-contig.c
+++ b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
@@ -48,16 +48,15 @@ struct vb2_dc_buf {
 
 static unsigned long vb2_dc_get_contiguous_size(struct sg_table *sgt)
 {
-	struct scatterlist *s;
 	dma_addr_t expected = sg_dma_address(sgt->sgl);
-	unsigned int i;
+	struct sg_dma_page_iter dma_iter;
 	unsigned long size = 0;
 
-	for_each_sg(sgt->sgl, s, sgt->nents, i) {
-		if (sg_dma_address(s) != expected)
+	for_each_sgtable_dma_page(sgt, &dma_iter, 0) {
+		if (sg_page_iter_dma_address(&dma_iter) != expected)
 			break;
-		expected = sg_dma_address(s) + sg_dma_len(s);
-		size += sg_dma_len(s);
+		expected += PAGE_SIZE;
+		size += PAGE_SIZE;
 	}
 	return size;
 }
@@ -99,8 +98,7 @@ static void vb2_dc_prepare(void *buf_priv)
 	if (!sgt || buf->db_attach)
 		return;
 
-	dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->orig_nents,
-			       buf->dma_dir);
+	dma_sync_sgtable_for_device(buf->dev, sgt, buf->dma_dir);
 }
 
 static void vb2_dc_finish(void *buf_priv)
@@ -112,7 +110,7 @@ static void vb2_dc_finish(void *buf_priv)
 	if (!sgt || buf->db_attach)
 		return;
 
-	dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
+	dma_sync_sgtable_for_cpu(buf->dev, sgt, buf->dma_dir);
 }
 
 /*********************************************/
@@ -273,8 +271,8 @@ static void vb2_dc_dmabuf_ops_detach(struct dma_buf *dbuf,
 		 * memory locations do not require any explicit cache
 		 * maintenance prior or after being used by the device.
 		 */
-		dma_unmap_sg_attrs(db_attach->dev, sgt->sgl, sgt->orig_nents,
-				   attach->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
+		dma_unmap_sgtable(db_attach->dev, sgt, attach->dma_dir,
+				  DMA_ATTR_SKIP_CPU_SYNC);
 	sg_free_table(sgt);
 	kfree(attach);
 	db_attach->priv = NULL;
@@ -299,8 +297,8 @@ static struct sg_table *vb2_dc_dmabuf_ops_map(
 
 	/* release any previous cache */
 	if (attach->dma_dir != DMA_NONE) {
-		dma_unmap_sg_attrs(db_attach->dev, sgt->sgl, sgt->orig_nents,
-				   attach->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
+		dma_unmap_sgtable(db_attach->dev, sgt, attach->dma_dir,
+				  DMA_ATTR_SKIP_CPU_SYNC);
 		attach->dma_dir = DMA_NONE;
 	}
 
@@ -308,9 +306,8 @@ static struct sg_table *vb2_dc_dmabuf_ops_map(
 	 * mapping to the client with new direction, no cache sync
 	 * required see comment in vb2_dc_dmabuf_ops_detach()
 	 */
-	sgt->nents = dma_map_sg_attrs(db_attach->dev, sgt->sgl, sgt->orig_nents,
-				      dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
-	if (!sgt->nents) {
+	if (dma_map_sgtable(db_attach->dev, sgt, dma_dir,
+			    DMA_ATTR_SKIP_CPU_SYNC)) {
 		pr_err("failed to map scatterlist\n");
 		mutex_unlock(lock);
 		return ERR_PTR(-EIO);
@@ -423,8 +420,8 @@ static void vb2_dc_put_userptr(void *buf_priv)
 		 * No need to sync to CPU, it's already synced to the CPU
 		 * since the finish() memop will have been called before this.
 		 */
-		dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
-				   buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
+		dma_unmap_sgtable(buf->dev, sgt, buf->dma_dir,
+				  DMA_ATTR_SKIP_CPU_SYNC);
 		pages = frame_vector_pages(buf->vec);
 		/* sgt should exist only if vector contains pages... */
 		BUG_ON(IS_ERR(pages));
@@ -521,9 +518,8 @@ static void *vb2_dc_get_userptr(struct device *dev, unsigned long vaddr,
 	 * No need to sync to the device, this will happen later when the
 	 * prepare() memop is called.
 	 */
-	sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
-				      buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
-	if (sgt->nents <= 0) {
+	if (dma_map_sgtable(buf->dev, sgt, buf->dma_dir,
+			    DMA_ATTR_SKIP_CPU_SYNC)) {
 		pr_err("failed to map scatterlist\n");
 		ret = -EIO;
 		goto fail_sgt_init;
@@ -545,8 +541,7 @@ static void *vb2_dc_get_userptr(struct device *dev, unsigned long vaddr,
 	return buf;
 
 fail_map_sg:
-	dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
-			   buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
+	dma_unmap_sgtable(buf->dev, sgt, buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
 
 fail_sgt_init:
 	sg_free_table(sgt);
diff --git a/drivers/media/common/videobuf2/videobuf2-dma-sg.c b/drivers/media/common/videobuf2/videobuf2-dma-sg.c
index 92072a08af25..6ddf953efa11 100644
--- a/drivers/media/common/videobuf2/videobuf2-dma-sg.c
+++ b/drivers/media/common/videobuf2/videobuf2-dma-sg.c
@@ -142,9 +142,8 @@ static void *vb2_dma_sg_alloc(struct device *dev, unsigned long dma_attrs,
 	 * No need to sync to the device, this will happen later when the
 	 * prepare() memop is called.
 	 */
-	sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
-				      buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
-	if (!sgt->nents)
+	if (dma_map_sgtable(buf->dev, sgt, buf->dma_dir,
+			    DMA_ATTR_SKIP_CPU_SYNC)) {
 		goto fail_map;
 
 	buf->handler.refcount = &buf->refcount;
@@ -180,8 +179,8 @@ static void vb2_dma_sg_put(void *buf_priv)
 	if (refcount_dec_and_test(&buf->refcount)) {
 		dprintk(1, "%s: Freeing buffer of %d pages\n", __func__,
 			buf->num_pages);
-		dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
-				   buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
+		dma_unmap_sgtable(buf->dev, sgt, buf->dma_dir,
+				  DMA_ATTR_SKIP_CPU_SYNC);
 		if (buf->vaddr)
 			vm_unmap_ram(buf->vaddr, buf->num_pages);
 		sg_free_table(buf->dma_sgt);
@@ -202,8 +201,7 @@ static void vb2_dma_sg_prepare(void *buf_priv)
 	if (buf->db_attach)
 		return;
 
-	dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->orig_nents,
-			       buf->dma_dir);
+	dma_sync_sgtable_for_device(buf->dev, sgt, buf->dma_dir);
 }
 
 static void vb2_dma_sg_finish(void *buf_priv)
@@ -215,7 +213,7 @@ static void vb2_dma_sg_finish(void *buf_priv)
 	if (buf->db_attach)
 		return;
 
-	dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
+	dma_sync_sgtable_for_cpu(buf->dev, sgt, buf->dma_dir);
 }
 
 static void *vb2_dma_sg_get_userptr(struct device *dev, unsigned long vaddr,
@@ -258,9 +256,8 @@ static void *vb2_dma_sg_get_userptr(struct device *dev, unsigned long vaddr,
 	 * No need to sync to the device, this will happen later when the
 	 * prepare() memop is called.
 	 */
-	sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
-				      buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
-	if (!sgt->nents)
+	if (dma_map_sgtable(buf->dev, sgt, buf->dma_dir,
+			    DMA_ATTR_SKIP_CPU_SYNC)) {
 		goto userptr_fail_map;
 
 	return buf;
@@ -286,8 +283,7 @@ static void vb2_dma_sg_put_userptr(void *buf_priv)
 
 	dprintk(1, "%s: Releasing userspace buffer of %d pages\n",
 	       __func__, buf->num_pages);
-	dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir,
-			   DMA_ATTR_SKIP_CPU_SYNC);
+	dma_unmap_sgtable(buf->dev, sgt, buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
 	if (buf->vaddr)
 		vm_unmap_ram(buf->vaddr, buf->num_pages);
 	sg_free_table(buf->dma_sgt);
@@ -410,8 +406,7 @@ static void vb2_dma_sg_dmabuf_ops_detach(struct dma_buf *dbuf,
 
 	/* release the scatterlist cache */
 	if (attach->dma_dir != DMA_NONE)
-		dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
-			attach->dma_dir);
+		dma_unmap_sgtable(db_attach->dev, sgt, attach->dma_dir);
 	sg_free_table(sgt);
 	kfree(attach);
 	db_attach->priv = NULL;
@@ -436,15 +431,12 @@ static struct sg_table *vb2_dma_sg_dmabuf_ops_map(
 
 	/* release any previous cache */
 	if (attach->dma_dir != DMA_NONE) {
-		dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
-			attach->dma_dir);
+		dma_unmap_sgtable(db_attach->dev, sgt, attach->dma_dir);
 		attach->dma_dir = DMA_NONE;
 	}
 
 	/* mapping to the client with new direction */
-	sgt->nents = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
-				dma_dir);
-	if (!sgt->nents) {
+	if (dma_map_sgtable(db_attach->dev, sgt, dma_dir, 0)) {
 		pr_err("failed to map scatterlist\n");
 		mutex_unlock(lock);
 		return ERR_PTR(-EIO);
diff --git a/drivers/media/common/videobuf2/videobuf2-vmalloc.c b/drivers/media/common/videobuf2/videobuf2-vmalloc.c
index c66fda4a65e4..bf5ac63a5742 100644
--- a/drivers/media/common/videobuf2/videobuf2-vmalloc.c
+++ b/drivers/media/common/videobuf2/videobuf2-vmalloc.c
@@ -229,7 +229,7 @@ static int vb2_vmalloc_dmabuf_ops_attach(struct dma_buf *dbuf,
 		kfree(attach);
 		return ret;
 	}
-	for_each_sg(sgt->sgl, sg, sgt->nents, i) {
+	for_each_sgtable_sg(sgt, sg, i) {
 		struct page *page = vmalloc_to_page(vaddr);
 
 		if (!page) {
@@ -259,8 +259,7 @@ static void vb2_vmalloc_dmabuf_ops_detach(struct dma_buf *dbuf,
 
 	/* release the scatterlist cache */
 	if (attach->dma_dir != DMA_NONE)
-		dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
-			attach->dma_dir);
+		dma_unmap_sgtable(db_attach->dev, sgt, attach->dma_dir, 0);
 	sg_free_table(sgt);
 	kfree(attach);
 	db_attach->priv = NULL;
@@ -285,15 +284,12 @@ static struct sg_table *vb2_vmalloc_dmabuf_ops_map(
 
 	/* release any previous cache */
 	if (attach->dma_dir != DMA_NONE) {
-		dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
-			attach->dma_dir);
+		dma_unmap_sgtable(db_attach->dev, sgt, attach->dma_dir, 0);
 		attach->dma_dir = DMA_NONE;
 	}
 
 	/* mapping to the client with new direction */
-	sgt->nents = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
-				dma_dir);
-	if (!sgt->nents) {
+	if (dma_map_sgtable(db_attach->dev, sgt, dma_dir, 0)) {
 		pr_err("failed to map scatterlist\n");
 		mutex_unlock(lock);
 		return ERR_PTR(-EIO);
-- 
2.17.1

Re: [PATCH v6 35/36] videobuf2: use sgtable-based scatterlist wrappers

[Robin Murphy]

On 2020-06-18 16:39, Marek Szyprowski wrote:
> Use recently introduced common wrappers operating directly on the struct
> sg_table objects and scatterlist page iterators to make the code a bit
> more compact, robust, easier to follow and copy/paste safe.
> 
> No functional change, because the code already properly did all the
> scaterlist related calls.
> 
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> ---
>   .../common/videobuf2/videobuf2-dma-contig.c   | 41 ++++++++-----------
>   .../media/common/videobuf2/videobuf2-dma-sg.c | 32 ++++++---------
>   .../common/videobuf2/videobuf2-vmalloc.c      | 12 ++----
>   3 files changed, 34 insertions(+), 51 deletions(-)
> 
> diff --git a/drivers/media/common/videobuf2/videobuf2-dma-contig.c b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> index f4b4a7c135eb..ba01a8692d88 100644
> --- a/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> +++ b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> @@ -48,16 +48,15 @@ struct vb2_dc_buf {
>   
>   static unsigned long vb2_dc_get_contiguous_size(struct sg_table *sgt)
>   {
> -	struct scatterlist *s;
>   	dma_addr_t expected = sg_dma_address(sgt->sgl);
> -	unsigned int i;
> +	struct sg_dma_page_iter dma_iter;
>   	unsigned long size = 0;
>   
> -	for_each_sg(sgt->sgl, s, sgt->nents, i) {
> -		if (sg_dma_address(s) != expected)
> +	for_each_sgtable_dma_page(sgt, &dma_iter, 0) {
> +		if (sg_page_iter_dma_address(&dma_iter) != expected)
>   			break;
> -		expected = sg_dma_address(s) + sg_dma_len(s);
> -		size += sg_dma_len(s);
> +		expected += PAGE_SIZE;
> +		size += PAGE_SIZE;

Same comment as for the DRM version. In fact, given that it's the same 
function with the same purpose, might it be worth hoisting out as a 
generic helper for the sg_table API itself?

>   	}
>   	return size;
>   }
[...]
> diff --git a/drivers/media/common/videobuf2/videobuf2-dma-sg.c b/drivers/media/common/videobuf2/videobuf2-dma-sg.c
> index 92072a08af25..6ddf953efa11 100644
> --- a/drivers/media/common/videobuf2/videobuf2-dma-sg.c
> +++ b/drivers/media/common/videobuf2/videobuf2-dma-sg.c
> @@ -142,9 +142,8 @@ static void *vb2_dma_sg_alloc(struct device *dev, unsigned long dma_attrs,
>   	 * No need to sync to the device, this will happen later when the
>   	 * prepare() memop is called.
>   	 */
> -	sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
> -				      buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
> -	if (!sgt->nents)
> +	if (dma_map_sgtable(buf->dev, sgt, buf->dma_dir,
> +			    DMA_ATTR_SKIP_CPU_SYNC)) {

As 0-day's explosions of nonsense imply, there's a rogue bracket here...

>   		goto fail_map;
>   
>   	buf->handler.refcount = &buf->refcount;
> @@ -180,8 +179,8 @@ static void vb2_dma_sg_put(void *buf_priv)
>   	if (refcount_dec_and_test(&buf->refcount)) {
>   		dprintk(1, "%s: Freeing buffer of %d pages\n", __func__,
>   			buf->num_pages);
> -		dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
> -				   buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
> +		dma_unmap_sgtable(buf->dev, sgt, buf->dma_dir,
> +				  DMA_ATTR_SKIP_CPU_SYNC);
>   		if (buf->vaddr)
>   			vm_unmap_ram(buf->vaddr, buf->num_pages);
>   		sg_free_table(buf->dma_sgt);
> @@ -202,8 +201,7 @@ static void vb2_dma_sg_prepare(void *buf_priv)
>   	if (buf->db_attach)
>   		return;
>   
> -	dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->orig_nents,
> -			       buf->dma_dir);
> +	dma_sync_sgtable_for_device(buf->dev, sgt, buf->dma_dir);
>   }
>   
>   static void vb2_dma_sg_finish(void *buf_priv)
> @@ -215,7 +213,7 @@ static void vb2_dma_sg_finish(void *buf_priv)
>   	if (buf->db_attach)
>   		return;
>   
> -	dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
> +	dma_sync_sgtable_for_cpu(buf->dev, sgt, buf->dma_dir);
>   }
>   
>   static void *vb2_dma_sg_get_userptr(struct device *dev, unsigned long vaddr,
> @@ -258,9 +256,8 @@ static void *vb2_dma_sg_get_userptr(struct device *dev, unsigned long vaddr,
>   	 * No need to sync to the device, this will happen later when the
>   	 * prepare() memop is called.
>   	 */
> -	sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
> -				      buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
> -	if (!sgt->nents)
> +	if (dma_map_sgtable(buf->dev, sgt, buf->dma_dir,
> +			    DMA_ATTR_SKIP_CPU_SYNC)) {

... and here.

Robin.