drm/ast: Don't grab dev->struct_mutex for in mmap offset ioctl

Since David Herrmann's mmap vma manager rework we don't need to grab
dev->struct_mutex any more to prevent races when looking up the mmap
offset. Drop it and instead don't forget to use the unref_unlocked
variant (since the drm core still cares).

Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

1 files changed, 5 insertions, 11 deletions

diff --git a/drivers/gpu/drm/ast/ast_main.c b/drivers/gpu/drm/ast/ast_main.c
index 035dacc93382..838217f8ce7d 100644
--- a/drivers/gpu/drm/ast/ast_main.c
+++ b/drivers/gpu/drm/ast/ast_main.c
@@ -571,24 +571,18 @@ ast_dumb_mmap_offset(struct drm_file *file,
                      uint64_t *offset)
 {
         struct drm_gem_object *obj;
-        int ret;
         struct ast_bo *bo;
 
-        mutex_lock(&dev->struct_mutex);
         obj = drm_gem_object_lookup(dev, file, handle);
-        if (obj == NULL) {
-                ret = -ENOENT;
-                goto out_unlock;
-        }
+        if (obj == NULL)
+                return -ENOENT;
 
         bo = gem_to_ast_bo(obj);
         *offset = ast_bo_mmap_offset(bo);
 
-        drm_gem_object_unreference(obj);
-        ret = 0;
-out_unlock:
-        mutex_unlock(&dev->struct_mutex);
-        return ret;
+        drm_gem_object_unreference_unlocked(obj);
+
+        return 0;
 
 }