[v7,01/36] drm: prime: add common helper to check scatterlist contiguity

Message ID 20200619103636.11974-2-m.szyprowski@samsung.com
State New
Headers show
Series
  • DRM: fix struct sg_table nents vs. orig_nents misuse
Related show

Commit Message

Marek Szyprowski June 19, 2020, 10:36 a.m.
It is a common operation done by DRM drivers to check the contiguity
of the DMA-mapped buffer described by a scatterlist in the
sg_table object. Let's add a common helper for this operation.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

---
 drivers/gpu/drm/drm_gem_cma_helper.c | 23 +++------------------
 drivers/gpu/drm/drm_prime.c          | 31 ++++++++++++++++++++++++++++
 include/drm/drm_prime.h              |  2 ++
 3 files changed, 36 insertions(+), 20 deletions(-)

-- 
2.17.1

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

Comments

Andrzej Hajda July 7, 2020, 2:30 p.m. | #1
On 19.06.2020 12:36, Marek Szyprowski wrote:
> It is a common operation done by DRM drivers to check the contiguity

> of the DMA-mapped buffer described by a scatterlist in the

> sg_table object. Let's add a common helper for this operation.

>

> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

> ---

>   drivers/gpu/drm/drm_gem_cma_helper.c | 23 +++------------------

>   drivers/gpu/drm/drm_prime.c          | 31 ++++++++++++++++++++++++++++

>   include/drm/drm_prime.h              |  2 ++

>   3 files changed, 36 insertions(+), 20 deletions(-)

>

> diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c

> index 06a5b9ee1fe0..41566a15dabd 100644

> --- a/drivers/gpu/drm/drm_gem_cma_helper.c

> +++ b/drivers/gpu/drm/drm_gem_cma_helper.c

> @@ -471,26 +471,9 @@ drm_gem_cma_prime_import_sg_table(struct drm_device *dev,

>   {

>   	struct drm_gem_cma_object *cma_obj;

>   

> -	if (sgt->nents != 1) {

> -		/* check if the entries in the sg_table are contiguous */

> -		dma_addr_t next_addr = sg_dma_address(sgt->sgl);

> -		struct scatterlist *s;

> -		unsigned int i;

> -

> -		for_each_sg(sgt->sgl, s, sgt->nents, i) {

> -			/*

> -			 * sg_dma_address(s) is only valid for entries

> -			 * that have sg_dma_len(s) != 0

> -			 */

> -			if (!sg_dma_len(s))

> -				continue;

> -

> -			if (sg_dma_address(s) != next_addr)

> -				return ERR_PTR(-EINVAL);

> -

> -			next_addr = sg_dma_address(s) + sg_dma_len(s);

> -		}

> -	}

> +	/* check if the entries in the sg_table are contiguous */

> +	if (drm_prime_get_contiguous_size(sgt) < attach->dmabuf->size)

> +		return ERR_PTR(-EINVAL);

>   

>   	/* Create a CMA GEM buffer. */

>   	cma_obj = __drm_gem_cma_create(dev, attach->dmabuf->size);

> diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c

> index bbfc713bfdc3..226cd6ad3985 100644

> --- a/drivers/gpu/drm/drm_prime.c

> +++ b/drivers/gpu/drm/drm_prime.c

> @@ -825,6 +825,37 @@ struct sg_table *drm_prime_pages_to_sg(struct page **pages, unsigned int nr_page

>   }

>   EXPORT_SYMBOL(drm_prime_pages_to_sg);

>   

> +/**

> + * drm_prime_get_contiguous_size - returns the contiguous size of the buffer

> + * @sgt: sg_table describing the buffer to check

> + *

> + * This helper calculates the contiguous size in the DMA address space

> + * of the the buffer described by the provided sg_table.

> + *

> + * This is useful for implementing

> + * &drm_gem_object_funcs.gem_prime_import_sg_table.

> + */

> +unsigned long drm_prime_get_contiguous_size(struct sg_table *sgt)

> +{

> +	dma_addr_t expected = sg_dma_address(sgt->sgl);

> +	struct scatterlist *sg;

> +	unsigned long size = 0;

> +	int i;

> +

> +	for_each_sgtable_dma_sg(sgt, sg, i) {

> +		unsigned int len = sg_dma_len(sg);

> +

> +		if (!len)

> +			break;



I wander if in some dark corners of the kernel 0-length buffers can be 
in use :)


> +		if (sg_dma_address(sg) != expected)

> +			break;

> +		expected += len;

> +		size += len;

> +	}

> +	return size;

> +}

> +EXPORT_SYMBOL(drm_prime_get_contiguous_size);

> +

>   /**

>    * drm_gem_prime_export - helper library implementation of the export callback

>    * @obj: GEM object to export

> diff --git a/include/drm/drm_prime.h b/include/drm/drm_prime.h

> index 9af7422b44cf..47ef11614627 100644

> --- a/include/drm/drm_prime.h

> +++ b/include/drm/drm_prime.h

> @@ -92,6 +92,8 @@ struct sg_table *drm_prime_pages_to_sg(struct page **pages, unsigned int nr_page

>   struct dma_buf *drm_gem_prime_export(struct drm_gem_object *obj,

>   				     int flags);

>   

> +unsigned long drm_prime_get_contiguous_size(struct sg_table *sgt);

> +


Reviewed-by <a.hajda@samsung.com>

Regards
Andrzej


>   /* helper functions for importing */

>   struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev,

>   						struct dma_buf *dma_buf,

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
Andrzej Hajda July 7, 2020, 3:03 p.m. | #2
On 07.07.2020 16:30, Andrzej Hajda wrote:
> On 19.06.2020 12:36, Marek Szyprowski wrote:

>> It is a common operation done by DRM drivers to check the contiguity

>> of the DMA-mapped buffer described by a scatterlist in the

>> sg_table object. Let's add a common helper for this operation.

>>

>> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

>> ---


Just fixing my signature :)

Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>


Regards
Andrzej

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

Patch

diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
index 06a5b9ee1fe0..41566a15dabd 100644
--- a/drivers/gpu/drm/drm_gem_cma_helper.c
+++ b/drivers/gpu/drm/drm_gem_cma_helper.c
@@ -471,26 +471,9 @@  drm_gem_cma_prime_import_sg_table(struct drm_device *dev,
 {
 	struct drm_gem_cma_object *cma_obj;
 
-	if (sgt->nents != 1) {
-		/* check if the entries in the sg_table are contiguous */
-		dma_addr_t next_addr = sg_dma_address(sgt->sgl);
-		struct scatterlist *s;
-		unsigned int i;
-
-		for_each_sg(sgt->sgl, s, sgt->nents, i) {
-			/*
-			 * sg_dma_address(s) is only valid for entries
-			 * that have sg_dma_len(s) != 0
-			 */
-			if (!sg_dma_len(s))
-				continue;
-
-			if (sg_dma_address(s) != next_addr)
-				return ERR_PTR(-EINVAL);
-
-			next_addr = sg_dma_address(s) + sg_dma_len(s);
-		}
-	}
+	/* check if the entries in the sg_table are contiguous */
+	if (drm_prime_get_contiguous_size(sgt) < attach->dmabuf->size)
+		return ERR_PTR(-EINVAL);
 
 	/* Create a CMA GEM buffer. */
 	cma_obj = __drm_gem_cma_create(dev, attach->dmabuf->size);
diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index bbfc713bfdc3..226cd6ad3985 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -825,6 +825,37 @@  struct sg_table *drm_prime_pages_to_sg(struct page **pages, unsigned int nr_page
 }
 EXPORT_SYMBOL(drm_prime_pages_to_sg);
 
+/**
+ * drm_prime_get_contiguous_size - returns the contiguous size of the buffer
+ * @sgt: sg_table describing the buffer to check
+ *
+ * This helper calculates the contiguous size in the DMA address space
+ * of the the buffer described by the provided sg_table.
+ *
+ * This is useful for implementing
+ * &drm_gem_object_funcs.gem_prime_import_sg_table.
+ */
+unsigned long drm_prime_get_contiguous_size(struct sg_table *sgt)
+{
+	dma_addr_t expected = sg_dma_address(sgt->sgl);
+	struct scatterlist *sg;
+	unsigned long size = 0;
+	int i;
+
+	for_each_sgtable_dma_sg(sgt, sg, i) {
+		unsigned int len = sg_dma_len(sg);
+
+		if (!len)
+			break;
+		if (sg_dma_address(sg) != expected)
+			break;
+		expected += len;
+		size += len;
+	}
+	return size;
+}
+EXPORT_SYMBOL(drm_prime_get_contiguous_size);
+
 /**
  * drm_gem_prime_export - helper library implementation of the export callback
  * @obj: GEM object to export
diff --git a/include/drm/drm_prime.h b/include/drm/drm_prime.h
index 9af7422b44cf..47ef11614627 100644
--- a/include/drm/drm_prime.h
+++ b/include/drm/drm_prime.h
@@ -92,6 +92,8 @@  struct sg_table *drm_prime_pages_to_sg(struct page **pages, unsigned int nr_page
 struct dma_buf *drm_gem_prime_export(struct drm_gem_object *obj,
 				     int flags);
 
+unsigned long drm_prime_get_contiguous_size(struct sg_table *sgt);
+
 /* helper functions for importing */
 struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev,
 						struct dma_buf *dma_buf,