diff mbox series

[v9,24/32] drm: host1x: fix common struct sg_table related issues

Message ID 20200826063316.23486-25-m.szyprowski@samsung.com (mailing list archive)
State New, archived
Headers show
Series [v9,01/32] drm: prime: add common helper to check scatterlist contiguity | expand

Commit Message

Marek Szyprowski Aug. 26, 2020, 6:33 a.m. UTC
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>
---
 drivers/gpu/host1x/job.c | 22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

Comments

Robin Murphy Sept. 1, 2020, 8:13 p.m. UTC | #1
On 2020-08-26 07:33, Marek Szyprowski wrote:
> 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.

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> ---
>   drivers/gpu/host1x/job.c | 22 ++++++++--------------
>   1 file changed, 8 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/gpu/host1x/job.c b/drivers/gpu/host1x/job.c
> index 89b6c14b7392..82d0a60ba3f7 100644
> --- a/drivers/gpu/host1x/job.c
> +++ b/drivers/gpu/host1x/job.c
> @@ -170,11 +170,9 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job)
>   				goto unpin;
>   			}
>   
> -			err = dma_map_sg(dev, sgt->sgl, sgt->nents, dir);
> -			if (!err) {
> -				err = -ENOMEM;
> +			err = dma_map_sgtable(dev, sgt, dir, 0);
> +			if (err)
>   				goto unpin;
> -			}
>   
>   			job->unpins[job->num_unpins].dev = dev;
>   			job->unpins[job->num_unpins].dir = dir;
> @@ -228,7 +226,7 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job)
>   		}
>   
>   		if (host->domain) {
> -			for_each_sg(sgt->sgl, sg, sgt->nents, j)
> +			for_each_sgtable_sg(sgt, sg, j)
>   				gather_size += sg->length;
>   			gather_size = iova_align(&host->iova, gather_size);
>   
> @@ -240,9 +238,9 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job)
>   				goto put;
>   			}
>   
> -			err = iommu_map_sg(host->domain,
> +			err = iommu_map_sgtable(host->domain,
>   					iova_dma_addr(&host->iova, alloc),
> -					sgt->sgl, sgt->nents, IOMMU_READ);
> +					sgt, IOMMU_READ);
>   			if (err == 0) {
>   				__free_iova(&host->iova, alloc);
>   				err = -EINVAL;
> @@ -252,12 +250,9 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job)
>   			job->unpins[job->num_unpins].size = gather_size;
>   			phys_addr = iova_dma_addr(&host->iova, alloc);
>   		} else if (sgt) {
> -			err = dma_map_sg(host->dev, sgt->sgl, sgt->nents,
> -					 DMA_TO_DEVICE);
> -			if (!err) {
> -				err = -ENOMEM;
> +			err = dma_map_sgtable(host->dev, sgt, DMA_TO_DEVICE, 0);
> +			if (err)
>   				goto put;
> -			}
>   
>   			job->unpins[job->num_unpins].dir = DMA_TO_DEVICE;
>   			job->unpins[job->num_unpins].dev = host->dev;
> @@ -660,8 +655,7 @@ void host1x_job_unpin(struct host1x_job *job)
>   		}
>   
>   		if (unpin->dev && sgt)
> -			dma_unmap_sg(unpin->dev, sgt->sgl, sgt->nents,
> -				     unpin->dir);
> +			dma_unmap_sgtable(unpin->dev, sgt, unpin->dir, 0);
>   
>   		host1x_bo_unpin(dev, unpin->bo, sgt);
>   		host1x_bo_put(unpin->bo);
>
diff mbox series

Patch

diff --git a/drivers/gpu/host1x/job.c b/drivers/gpu/host1x/job.c
index 89b6c14b7392..82d0a60ba3f7 100644
--- a/drivers/gpu/host1x/job.c
+++ b/drivers/gpu/host1x/job.c
@@ -170,11 +170,9 @@  static unsigned int pin_job(struct host1x *host, struct host1x_job *job)
 				goto unpin;
 			}
 
-			err = dma_map_sg(dev, sgt->sgl, sgt->nents, dir);
-			if (!err) {
-				err = -ENOMEM;
+			err = dma_map_sgtable(dev, sgt, dir, 0);
+			if (err)
 				goto unpin;
-			}
 
 			job->unpins[job->num_unpins].dev = dev;
 			job->unpins[job->num_unpins].dir = dir;
@@ -228,7 +226,7 @@  static unsigned int pin_job(struct host1x *host, struct host1x_job *job)
 		}
 
 		if (host->domain) {
-			for_each_sg(sgt->sgl, sg, sgt->nents, j)
+			for_each_sgtable_sg(sgt, sg, j)
 				gather_size += sg->length;
 			gather_size = iova_align(&host->iova, gather_size);
 
@@ -240,9 +238,9 @@  static unsigned int pin_job(struct host1x *host, struct host1x_job *job)
 				goto put;
 			}
 
-			err = iommu_map_sg(host->domain,
+			err = iommu_map_sgtable(host->domain,
 					iova_dma_addr(&host->iova, alloc),
-					sgt->sgl, sgt->nents, IOMMU_READ);
+					sgt, IOMMU_READ);
 			if (err == 0) {
 				__free_iova(&host->iova, alloc);
 				err = -EINVAL;
@@ -252,12 +250,9 @@  static unsigned int pin_job(struct host1x *host, struct host1x_job *job)
 			job->unpins[job->num_unpins].size = gather_size;
 			phys_addr = iova_dma_addr(&host->iova, alloc);
 		} else if (sgt) {
-			err = dma_map_sg(host->dev, sgt->sgl, sgt->nents,
-					 DMA_TO_DEVICE);
-			if (!err) {
-				err = -ENOMEM;
+			err = dma_map_sgtable(host->dev, sgt, DMA_TO_DEVICE, 0);
+			if (err)
 				goto put;
-			}
 
 			job->unpins[job->num_unpins].dir = DMA_TO_DEVICE;
 			job->unpins[job->num_unpins].dev = host->dev;
@@ -660,8 +655,7 @@  void host1x_job_unpin(struct host1x_job *job)
 		}
 
 		if (unpin->dev && sgt)
-			dma_unmap_sg(unpin->dev, sgt->sgl, sgt->nents,
-				     unpin->dir);
+			dma_unmap_sgtable(unpin->dev, sgt, unpin->dir, 0);
 
 		host1x_bo_unpin(dev, unpin->bo, sgt);
 		host1x_bo_put(unpin->bo);