1 files changed, 14 insertions, 7 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
index eca2ce60d440..d73ea9c04227 100644
--- a/drivers/gpu/drm/radeon/radeon_ttm.c
+++ b/drivers/gpu/drm/radeon/radeon_ttm.c
@@ -675,10 +675,17 @@ static struct ttm_tt *radeon_ttm_tt_create(struct ttm_bo_device *bdev,
         return &gtt->ttm.ttm;
 }
 
+static struct radeon_ttm_tt *radeon_ttm_tt_to_gtt(struct ttm_tt *ttm)
+{
+        if (!ttm || ttm->func != &radeon_backend_func)
+                return NULL;
+        return (struct radeon_ttm_tt *)ttm;
+}
+
 static int radeon_ttm_tt_populate(struct ttm_tt *ttm)
 {
+        struct radeon_ttm_tt *gtt = radeon_ttm_tt_to_gtt(ttm);
         struct radeon_device *rdev;
-        struct radeon_ttm_tt *gtt = (void *)ttm;
         unsigned i;
         int r;
         bool slave = !!(ttm->page_flags & TTM_PAGE_FLAG_SG);
@@ -686,7 +693,7 @@ static int radeon_ttm_tt_populate(struct ttm_tt *ttm)
         if (ttm->state != tt_unpopulated)
                 return 0;
 
-        if (gtt->userptr) {
+        if (gtt && gtt->userptr) {
                 ttm->sg = kcalloc(1, sizeof(struct sg_table), GFP_KERNEL);
                 if (!ttm->sg)
                         return -ENOMEM;
@@ -741,11 +748,11 @@ static int radeon_ttm_tt_populate(struct ttm_tt *ttm)
 static void radeon_ttm_tt_unpopulate(struct ttm_tt *ttm)
 {
         struct radeon_device *rdev;
-        struct radeon_ttm_tt *gtt = (void *)ttm;
+        struct radeon_ttm_tt *gtt = radeon_ttm_tt_to_gtt(ttm);
         unsigned i;
         bool slave = !!(ttm->page_flags & TTM_PAGE_FLAG_SG);
 
-        if (gtt->userptr) {
+        if (gtt && gtt->userptr) {
                 kfree(ttm->sg);
                 ttm->page_flags &= ~TTM_PAGE_FLAG_SG;
                 return;
@@ -782,7 +789,7 @@ static void radeon_ttm_tt_unpopulate(struct ttm_tt *ttm)
 int radeon_ttm_tt_set_userptr(struct ttm_tt *ttm, uint64_t addr,
                               uint32_t flags)
 {
-        struct radeon_ttm_tt *gtt = (void *)ttm;
+        struct radeon_ttm_tt *gtt = radeon_ttm_tt_to_gtt(ttm);
 
         if (gtt == NULL)
                 return -EINVAL;
@@ -795,7 +802,7 @@ int radeon_ttm_tt_set_userptr(struct ttm_tt *ttm, uint64_t addr,
 
 bool radeon_ttm_tt_has_userptr(struct ttm_tt *ttm)
 {
-        struct radeon_ttm_tt *gtt = (void *)ttm;
+        struct radeon_ttm_tt *gtt = radeon_ttm_tt_to_gtt(ttm);
 
         if (gtt == NULL)
                 return false;
@@ -805,7 +812,7 @@ bool radeon_ttm_tt_has_userptr(struct ttm_tt *ttm)
 
 bool radeon_ttm_tt_is_readonly(struct ttm_tt *ttm)
 {
-        struct radeon_ttm_tt *gtt = (void *)ttm;
+        struct radeon_ttm_tt *gtt = radeon_ttm_tt_to_gtt(ttm);
 
         if (gtt == NULL)
                 return false;