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

[Matthew Auld]

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.a...@intel.com>
Cc: Christian König <christian.koe...@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