drm: extract legacy ctxbitmap flushing

The ctxbitmap code is only used by legacy drivers so lets try to keep it
as separated as possible. Furthermore, the locking is non-obvious and
kinda weird with ctxlist_mutex *and* struct_mutex. Keeping all ctxbitmap
access in one file is much easier to review and makes drm_release() more
readable.
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>

drivers/gpu/drm/drm_context.c

@@ -111,6 +111,36 @@ void drm_ctxbitmap_cleanup(struct drm_device * dev)
 	mutex_unlock(&dev->struct_mutex);
 }
 
+/**
+ * drm_ctxbitmap_flush() - Flush all contexts owned by a file
+ * @dev: DRM device to operate on
+ * @file: Open file to flush contexts for
+ *
+ * This iterates over all contexts on @dev and drops them if they're owned by
+ * @file. Note that after this call returns, new contexts might be added if
+ * the file is still alive.
+ */
+void drm_ctxbitmap_flush(struct drm_device *dev, struct drm_file *file)
+{
+	struct drm_ctx_list *pos, *tmp;
+
+	mutex_lock(&dev->ctxlist_mutex);
+
+	list_for_each_entry_safe(pos, tmp, &dev->ctxlist, head) {
+		if (pos->tag == file &&
+		    pos->handle != DRM_KERNEL_CONTEXT) {
+			if (dev->driver->context_dtor)
+				dev->driver->context_dtor(dev, pos->handle);
+
+			drm_ctxbitmap_free(dev, pos->handle);
+			list_del(&pos->head);
+			kfree(pos);
+		}
+	}
+
+	mutex_unlock(&dev->ctxlist_mutex);
+}
+
 /*@}*/
 
 /******************************************************************/

drivers/gpu/drm/drm_fops.c

@@ -457,25 +457,7 @@ int drm_release(struct inode *inode, struct file *filp)
 	if (dev->driver->driver_features & DRIVER_GEM)
 		drm_gem_release(dev, file_priv);
 
-	mutex_lock(&dev->ctxlist_mutex);
-	if (!list_empty(&dev->ctxlist)) {
-		struct drm_ctx_list *pos, *n;
-
-		list_for_each_entry_safe(pos, n, &dev->ctxlist, head) {
-			if (pos->tag == file_priv &&
-			    pos->handle != DRM_KERNEL_CONTEXT) {
-				if (dev->driver->context_dtor)
-					dev->driver->context_dtor(dev,
-								  pos->handle);
-
-				drm_ctxbitmap_free(dev, pos->handle);
-
-				list_del(&pos->head);
-				kfree(pos);
-			}
-		}
-	}
-	mutex_unlock(&dev->ctxlist_mutex);
+	drm_ctxbitmap_flush(dev, file_priv);
 
 	mutex_lock(&dev->master_mutex);
 

include/drm/drmP.h

@@ -1242,6 +1242,7 @@ extern int drm_rmctx(struct drm_device *dev, void *data,
 extern int drm_ctxbitmap_init(struct drm_device *dev);
 extern void drm_ctxbitmap_cleanup(struct drm_device *dev);
 extern void drm_ctxbitmap_free(struct drm_device *dev, int ctx_handle);
+extern void drm_ctxbitmap_flush(struct drm_device *dev, struct drm_file *file);
 
 extern int drm_setsareactx(struct drm_device *dev, void *data,
 			   struct drm_file *file_priv);