Re: [RFC 10/17] drm: radeon: fix sg_table nents vs. orig_nents misuse

2020-04-28 Thread Christian König 

Am 28.04.20 um 15:19 schrieb 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 


Reviewed-by: Christian König 


---
  drivers/gpu/drm/radeon/radeon_ttm.c | 10 +-
  1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c 
b/drivers/gpu/drm/radeon/radeon_ttm.c
index 5d50c9e..4770880 100644
--- a/drivers/gpu/drm/radeon/radeon_ttm.c
+++ b/drivers/gpu/drm/radeon/radeon_ttm.c
@@ -481,7 +481,7 @@ static int radeon_ttm_tt_pin_userptr(struct ttm_tt *ttm)
  {
struct radeon_device *rdev = radeon_get_rdev(ttm->bdev);
struct radeon_ttm_tt *gtt = (void *)ttm;
-   unsigned pinned = 0, nents;
+   unsigned pinned = 0;
int r;
  
  	int write = !(gtt->userflags & RADEON_GEM_USERPTR_READONLY);

@@ -522,8 +522,8 @@ static int radeon_ttm_tt_pin_userptr(struct ttm_tt *ttm)
goto release_sg;
  
  	r = -ENOMEM;

-   nents = dma_map_sg(rdev->dev, ttm->sg->sgl, ttm->sg->nents, direction);
-   if (nents == 0)
+   ttm->sg->nents = dma_map_sg(rdev->dev, ttm->sg->sgl,
+   if (ttm->sg->nents == 0)
goto release_sg;
  
  	drm_prime_sg_to_page_addr_arrays(ttm->sg, ttm->pages,

@@ -554,9 +554,9 @@ static void radeon_ttm_tt_unpin_userptr(struct ttm_tt *ttm)
return;
  
  	/* free the sg table and pages again */

-   dma_unmap_sg(rdev->dev, ttm->sg->sgl, ttm->sg->nents, direction);
+   dma_unmap_sg(rdev->dev, ttm->sg->sgl, ttm->sg->orig_nents, direction);
  
-	for_each_sg_page(ttm->sg->sgl, _iter, ttm->sg->nents, 0) {

+   for_each_sg_page(ttm->sg->sgl, _iter, ttm->sg->orig_nents, 0) {
struct page *page = sg_page_iter_page(_iter);
if (!(gtt->userflags & RADEON_GEM_USERPTR_READONLY))
set_page_dirty(page);


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[RFC 10/17] drm: radeon: fix sg_table nents vs. orig_nents misuse

2020-04-28 Thread 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 
---
 drivers/gpu/drm/radeon/radeon_ttm.c | 10 +-
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c 
b/drivers/gpu/drm/radeon/radeon_ttm.c
index 5d50c9e..4770880 100644
--- a/drivers/gpu/drm/radeon/radeon_ttm.c
+++ b/drivers/gpu/drm/radeon/radeon_ttm.c
@@ -481,7 +481,7 @@ static int radeon_ttm_tt_pin_userptr(struct ttm_tt *ttm)
 {
struct radeon_device *rdev = radeon_get_rdev(ttm->bdev);
struct radeon_ttm_tt *gtt = (void *)ttm;
-   unsigned pinned = 0, nents;
+   unsigned pinned = 0;
int r;
 
int write = !(gtt->userflags & RADEON_GEM_USERPTR_READONLY);
@@ -522,8 +522,8 @@ static int radeon_ttm_tt_pin_userptr(struct ttm_tt *ttm)
goto release_sg;
 
r = -ENOMEM;
-   nents = dma_map_sg(rdev->dev, ttm->sg->sgl, ttm->sg->nents, direction);
-   if (nents == 0)
+   ttm->sg->nents = dma_map_sg(rdev->dev, ttm->sg->sgl,
+   if (ttm->sg->nents == 0)
goto release_sg;
 
drm_prime_sg_to_page_addr_arrays(ttm->sg, ttm->pages,
@@ -554,9 +554,9 @@ static void radeon_ttm_tt_unpin_userptr(struct ttm_tt *ttm)
return;
 
/* free the sg table and pages again */
-   dma_unmap_sg(rdev->dev, ttm->sg->sgl, ttm->sg->nents, direction);
+   dma_unmap_sg(rdev->dev, ttm->sg->sgl, ttm->sg->orig_nents, direction);
 
-   for_each_sg_page(ttm->sg->sgl, _iter, ttm->sg->nents, 0) {
+   for_each_sg_page(ttm->sg->sgl, _iter, ttm->sg->orig_nents, 0) {
struct page *page = sg_page_iter_page(_iter);
if (!(gtt->userflags & RADEON_GEM_USERPTR_READONLY))
set_page_dirty(page);
-- 
1.9.1

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