[Intel-gfx] [PATCH] drm/ttm: move bo->resource check in vm_access

[Matthew Auld <matthew.auld@intel.com>]

Touching bo->resource looks like it should require first locking the
object, since this state is dynamic and could potentially change from
under us.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/ttm/ttm_bo_vm.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 38119311284d..8a0de14d8c85 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -412,13 +412,15 @@ int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
 		 << PAGE_SHIFT);
 	int ret;
 
-	if (len < 1 || (offset + len) >> PAGE_SHIFT > bo->resource->num_pages)
-		return -EIO;
-
 	ret = ttm_bo_reserve(bo, true, false, NULL);
 	if (ret)
 		return ret;
 
+	if (len < 1 || (offset + len) >> PAGE_SHIFT > bo->resource->num_pages) {
+		ret = -EIO;
+		goto out_reserve;
+	}
+
 	switch (bo->resource->mem_type) {
 	case TTM_PL_SYSTEM:
 		fallthrough;
@@ -433,6 +435,7 @@ int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
 			ret = -EIO;
 	}
 
+out_reserve:
 	ttm_bo_unreserve(bo);
 
 	return ret;
-- 
2.37.3