drm/cirrus: 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>

diff --git a/drivers/gpu/drm/cirrus/cirrus_main.c b/drivers/gpu/drm/cirrus/cirrus_main.c
index e4b976658087100304cd76f66330c16b9dcb7271..055fd86ba717d3283c71fbefe398b257ec8e1c20 100644 (file)
--- a/drivers/gpu/drm/cirrus/cirrus_main.c
+++ b/drivers/gpu/drm/cirrus/cirrus_main.c
@@ -293,25 +293,18 @@ cirrus_dumb_mmap_offset(struct drm_file *file,
                     uint64_t *offset)
 {
        struct drm_gem_object *obj;
-       int ret;
        struct cirrus_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_cirrus_bo(obj);
        *offset = cirrus_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;
 }
 
 bool cirrus_check_framebuffer(struct cirrus_device *cdev, int width, int height,