[PATCH v2] drm: Replace NULL with error value in drm_prime_pages_to_sg

[Oleksandr Andrushchenko]

From: Oleksandr Andrushchenko <oleksandr_andrushchenko at epam.com>

Dan Carpenter has reported that there is the following static checker
warning:
	drivers/gpu/drm/drm_prime.c:317 drm_gem_map_dma_buf()
	warn: 'sgt' can also be NULL

314	sgt = obj->dev->driver->gem_prime_get_sg_table(obj);
315
316	if (!IS_ERR(sgt)) {
317		if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir,

Problematic functions are xen_drm_front_gem_get_sg_table and
drm_gem_cma_prime_get_sg_table. Fix those by replacing NULL with error value.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko at epam.com>
Reported-by: Dan Carpenter <dan.carpenter at oracle.com>
---
 drivers/gpu/drm/drm_gem_cma_helper.c    | 2 +-
 drivers/gpu/drm/xen/xen_drm_front_gem.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
index 80a5115c3846..ce868ce288fb 100644
--- a/drivers/gpu/drm/drm_gem_cma_helper.c
+++ b/drivers/gpu/drm/drm_gem_cma_helper.c
@@ -436,7 +436,7 @@ struct sg_table *drm_gem_cma_prime_get_sg_table(struct drm_gem_object *obj)
 
 	sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
 	if (!sgt)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	ret = dma_get_sgtable(obj->dev->dev, sgt, cma_obj->vaddr,
 			      cma_obj->paddr, obj->size);
diff --git a/drivers/gpu/drm/xen/xen_drm_front_gem.c b/drivers/gpu/drm/xen/xen_drm_front_gem.c
index c85bfe7571cb..47ff019d3aef 100644
--- a/drivers/gpu/drm/xen/xen_drm_front_gem.c
+++ b/drivers/gpu/drm/xen/xen_drm_front_gem.c
@@ -179,7 +179,7 @@ struct sg_table *xen_drm_front_gem_get_sg_table(struct drm_gem_object *gem_obj)
 	struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj);
 
 	if (!xen_obj->pages)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	return drm_prime_pages_to_sg(xen_obj->pages, xen_obj->num_pages);
 }
-- 
2.17.1