drm: Hide master MAP cleanup in drm_bufs.c

And again make sure it's a no-op for modern drivers. Another case of
dev->struct_mutex gone for modern drivers!

Note that the entirety of the legacy addmap interface is now protected
by DRIVER_MODESET. Note that just auditing kernel code is not enough,
since userspace loves to set up legacy maps on it's own for various
things - with ums userspace and kernel space share control over
resources.

v2: Also add a DRIVER_* check like for all other maps functions to
really short-circuit the code. And give drm_legacy_rmmap used by the
dev unregister code the same treatment.

v3:
- remove redundant return; (Alex, Chris)
- don't special case nouveau with DRIVER_KMS_LEGACY_CONTEXT.

v4: Again special case nouveau. The problem is not directly in the
ddx, but that it calls dri1 functions from the X server. And those do
call drmAddMap. Fixed only in

    commit b1a630b48210d6a3c44994fce1b73273000ace5c
    Author: Dave Airlie <airlied@redhat.com>
    Date:   Wed Nov 7 14:45:14 2012 +1000

        nouveau: drop DRI1 device open interface.

Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1461741618-12679-1-git-send-email-daniel.vetter@ffwll.ch

drivers/gpu/drm/drm_bufs.c

@@ -542,18 +542,35 @@ int drm_legacy_rmmap_locked(struct drm_device *dev, struct drm_local_map *map)
 }
 EXPORT_SYMBOL(drm_legacy_rmmap_locked);
 
-int drm_legacy_rmmap(struct drm_device *dev, struct drm_local_map *map)
+void drm_legacy_rmmap(struct drm_device *dev, struct drm_local_map *map)
 {
-	int ret;
+	if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT) &&
+	    drm_core_check_feature(dev, DRIVER_MODESET))
+		return;
 
 	mutex_lock(&dev->struct_mutex);
-	ret = drm_legacy_rmmap_locked(dev, map);
+	drm_legacy_rmmap_locked(dev, map);
 	mutex_unlock(&dev->struct_mutex);
-
-	return ret;
 }
 EXPORT_SYMBOL(drm_legacy_rmmap);
 
+void drm_legacy_master_rmmaps(struct drm_device *dev, struct drm_master *master)
+{
+	struct drm_map_list *r_list, *list_temp;
+
+	if (drm_core_check_feature(dev, DRIVER_MODESET))
+		return;
+
+	mutex_lock(&dev->struct_mutex);
+	list_for_each_entry_safe(r_list, list_temp, &dev->maplist, head) {
+		if (r_list->master == master) {
+			drm_legacy_rmmap_locked(dev, r_list->map);
+			r_list = NULL;
+		}
+	}
+	mutex_unlock(&dev->struct_mutex);
+}
+
 /* The rmmap ioctl appears to be unnecessary.  All mappings are torn down on
  * the last close of the device, and this is necessary for cleanup when things
  * exit uncleanly.  Therefore, having userland manually remove mappings seems