drm/i915: Remove locking for get-caching query

Reading a single value from the object, the locking only provides futile
protection against userspace races. The locking is useless so remove it.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index c378f04..9c195cc 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3842,17 +3842,10 @@ int i915_gem_get_caching_ioctl(struct drm_device *dev, void *data,
 {
        struct drm_i915_gem_caching *args = data;
        struct drm_i915_gem_object *obj;
-       int ret;
-
-       ret = i915_mutex_lock_interruptible(dev);
-       if (ret)
-               return ret;
 
        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
-       if (&obj->base == NULL) {
-               ret = -ENOENT;
-               goto unlock;
-       }
+       if (&obj->base == NULL)
+               return -ENOENT;
 
        switch (obj->cache_level) {
        case I915_CACHE_LLC:
@@ -3869,10 +3862,8 @@ int i915_gem_get_caching_ioctl(struct drm_device *dev, void *data,
                break;
        }
 
-       drm_gem_object_unreference(&obj->base);
-unlock:
-       mutex_unlock(&dev->struct_mutex);
-       return ret;
+       drm_gem_object_unreference_unlocked(&obj->base);
+       return 0;
 }
 
 int i915_gem_set_caching_ioctl(struct drm_device *dev, void *data,