[RFC 01/17] drm: core: fix sg_table nents vs. orig_nents misuse

Marek Szyprowski
2020-04-28T13:21:58Z

drivers/gpu/drm/drm_cache.c | 2 +-
drivers/gpu/drm/drm_gem_shmem_helper.c | 7 ++++---
drivers/gpu/drm/drm_prime.c | 9 +++++----
3 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/drm_cache.c b/drivers/gpu/drm/drm_cache.c
index 03e01b0..63bd497 100644
--- a/drivers/gpu/drm/drm_cache.c
+++ b/drivers/gpu/drm/drm_cache.c
@@ -127,7 +127,7 @@ static void drm_cache_flush_clflush(struct page *pages[],
struct sg_page_iter sg_iter;

mb(); /*CLFLUSH is ordered only by using memory barriers*/
- for_each_sg_page(st->sgl, &sg_iter, st->nents, 0)
+ for_each_sg_page(st->sgl, &sg_iter, st->orig_nents, 0)
drm_clflush_page(sg_page_iter_page(&sg_iter));
mb(); /*Make sure that all cache line entry is flushed*/

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index df31e57..f47caa7 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -118,7 +118,7 @@ void drm_gem_shmem_free_object(struct drm_gem_object *obj)
} else {
if (shmem->sgt) {
dma_unmap_sg(obj->dev->dev, shmem->sgt->sgl,
- shmem->sgt->nents, DMA_BIDIRECTIONAL);
+ shmem->sgt->orig_nents, DMA_BIDIRECTIONAL);
sg_free_table(shmem->sgt);
kfree(shmem->sgt);
}
@@ -396,7 +396,7 @@ void drm_gem_shmem_purge_locked(struct drm_gem_object *obj)
WARN_ON(!drm_gem_shmem_is_purgeable(shmem));

dma_unmap_sg(obj->dev->dev, shmem->sgt->sgl,
- shmem->sgt->nents, DMA_BIDIRECTIONAL);
+ shmem->sgt->orig_nents, DMA_BIDIRECTIONAL);
sg_free_table(shmem->sgt);
kfree(shmem->sgt);
shmem->sgt = NULL;
@@ -623,7 +623,8 @@ struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_object *obj)
goto err_put_pages;
}
/* Map the pages for use by the h/w. */
- dma_map_sg(obj->dev->dev, sgt->sgl, sgt->nents, DMA_BIDIRECTIONAL);
+ sgt->nents = dma_map_sg(obj->dev->dev, sgt->sgl, sgt->orig_nents,
+ DMA_BIDIRECTIONAL);

shmem->sgt = sgt;

diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index 282774e..f3e2d2a 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -626,8 +626,9 @@ struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
else
sgt = obj->dev->driver->gem_prime_get_sg_table(obj);

- if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir,
- DMA_ATTR_SKIP_CPU_SYNC)) {
+ sgt->nents = dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->orig_nents,
+ dir, DMA_ATTR_SKIP_CPU_SYNC);
+ if (!sgt->nents) {
sg_free_table(sgt);
kfree(sgt);
sgt = ERR_PTR(-ENOMEM);
@@ -652,7 +653,7 @@ void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
if (!sgt)
return;

- dma_unmap_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir,
+ dma_unmap_sg_attrs(attach->dev, sgt->sgl, sgt->orig_nents, dir,
DMA_ATTR_SKIP_CPU_SYNC);
sg_free_table(sgt);
kfree(sgt);
@@ -975,7 +976,7 @@ int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,
*/
page_index = 0;
dma_index = 0;
- for_each_sg(sgt->sgl, sg, sgt->nents, count) {
+ for_each_sg(sgt->sgl, sg, sgt->orig_nents, count) {
page_len = sg->length;
page = sg_page(sg);
dma_len = sg_dma_len(sg);