On 03/23/2018 05:18 AM, Jesper Dangaard Brouer wrote:

+
+	/* Note, below struct compat code was primarily needed when
+	 * page_pool code lived under MM-tree control, given mmots and
+	 * net-next trees progress in very different rates.
+	 *
+	 * Allow kernel devel trees and driver to progress at different rates
+	 */
+	param_copy_sz = PAGE_POOL_PARAMS_SIZE;
+	memset(&pool->p, 0, param_copy_sz);
+	if (params->size < param_copy_sz) {
+		/* Older module calling newer kernel, handled by only
+		 * copying supplied size, and keep remaining params zero
+		 */
+		param_copy_sz = params->size;
+	} else if (params->size > param_copy_sz) {
+		/* Newer module calling older kernel. Need to validate
+		 * no new features were requested.
+		 */
+		unsigned char *addr = (unsigned char *)params + param_copy_sz;
+		unsigned char *end  = (unsigned char *)params + params->size;
+
+		for (; addr < end; addr++) {
+			if (*addr != 0)
+				return -E2BIG;
+		}
+	}

I do not see the need for this part.