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Commit 2ddea3fd authored by Dave Airlie's avatar Dave Airlie
Browse files

drm/modes: reduce fb_lock to just protecting lists 



This reduces the fb_lock to just protecting the num_fb/fb_list.

"Previously fb refcounting, and especially the weak reference
(kref_get_unless_zero) used in fb lookups have been protected by fb_lock.
But with the refactoring to share refcounting in the drm_mode_object base
class that switched to being protected by idr_mutex, which means fb_lock
critical sections can be reduced."

Reviewed-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
parent 72fe90b8

drivers/gpu/drm/drm_crtc.c

+1 −8
Original line number Diff line number Diff line
@@ -433,9 +433,7 @@ static void drm_framebuffer_free(struct kref *kref) 
	 * The lookup idr holds a weak reference, which has not necessarily been

	 * removed at this point. Check for that.

	 */

	mutex_lock(&dev->mode_config.fb_lock);

	drm_mode_object_unregister(dev, &fb->base);

	mutex_unlock(&dev->mode_config.fb_lock);



	fb->funcs->destroy(fb);

}
@@ -475,9 +473,9 @@ int drm_framebuffer_init(struct drm_device *dev, struct drm_framebuffer *fb, 
	mutex_lock(&dev->mode_config.fb_lock);

	dev->mode_config.num_fb++;

	list_add(&fb->head, &dev->mode_config.fb_list);

	mutex_unlock(&dev->mode_config.fb_lock);



	drm_mode_object_register(dev, &fb->base);

	mutex_unlock(&dev->mode_config.fb_lock);

out:

	return ret;

}
@@ -498,12 +496,9 @@ struct drm_framebuffer *drm_framebuffer_lookup(struct drm_device *dev, 
	struct drm_mode_object *obj;

	struct drm_framebuffer *fb = NULL;



	mutex_lock(&dev->mode_config.fb_lock);

	obj = _object_find(dev, id, DRM_MODE_OBJECT_FB);

	if (obj)

		fb = obj_to_fb(obj);

	mutex_unlock(&dev->mode_config.fb_lock);



	return fb;

}

EXPORT_SYMBOL(drm_framebuffer_lookup);
@@ -526,10 +521,8 @@ void drm_framebuffer_unregister_private(struct drm_framebuffer *fb) 


	dev = fb->dev;



	mutex_lock(&dev->mode_config.fb_lock);

	/* Mark fb as reaped and drop idr ref. */

	drm_mode_object_unregister(dev, &fb->base);

	mutex_unlock(&dev->mode_config.fb_lock);

}

EXPORT_SYMBOL(drm_framebuffer_unregister_private);