RE: [PATCH v4 38/38] videobuf2: use sgtable-based scatterlist wrappers

-----Original Message-----
From: dri-devel <redacted> On Behalf Of
Marek Szyprowski
Sent: Tuesday, May 12, 2020 5:01 AM
To: <redacted>; <redacted>;
linaro-mm-sig@lists.linaro.org; linux-kernel@vger.kernel.org
Cc: Pawel Osciak <redacted>; Bartlomiej Zolnierkiewicz
[off-list ref]; David Airlie [off-list ref]; linux-
media@vger.kernel.org; Hans Verkuil [off-list ref]; Mauro
Carvalho Chehab [off-list ref]; Robin Murphy
[off-list ref]; Christoph Hellwig [off-list ref]; linux-arm-
kernel@lists.infradead.org; Marek Szyprowski
[off-list ref]
Subject: [PATCH v4 38/38] videobuf2: use sgtable-based scatterlist wrappers

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>
---
For more information, see '[PATCH v4 00/38] DRM: fix struct sg_table nents
vs. orig_nents misuse' thread:
https://lore.kernel.org/dri-devel/20200512085710.14688-1-
m.szyprowski@samsung.com/T/
---
.../media/common/videobuf2/videobuf2-dma-contig.c  | 41 ++++++++++----
--------
drivers/media/common/videobuf2/videobuf2-dma-sg.c  | 32 +++++++--------
--
drivers/media/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 d3a3ee5..bf31a9d 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-

quoted

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-

quoted

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-

quoted

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-

quoted

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 92072a0..6ddf953 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-

quoted

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-

quoted

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 c66fda4..bf5ac63 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);
--
1.9.1

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