From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756828AbcA2TrS (ORCPT ); Fri, 29 Jan 2016 14:47:18 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53531 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753757AbcA2TrR (ORCPT ); Fri, 29 Jan 2016 14:47:17 -0500 Date: Fri, 29 Jan 2016 13:47:15 -0600 From: Josh Poimboeuf To: Steven Rostedt Cc: Miroslav Benes , Jessica Yu , Seth Jennings , Jiri Kosina , Vojtech Pavlik , Ingo Molnar , live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, Rusty Russell Subject: Re: [PATCH 1/2] livepatch: Implement separate coming and going module notifiers Message-ID: <20160129194715.GD19101@treble.redhat.com> References: <1454049827-3726-1-git-send-email-jeyu@redhat.com> <1454049827-3726-2-git-send-email-jeyu@redhat.com> <20160129173010.GA19101@treble.redhat.com> <20160129124014.204020ed@gandalf.local.home> <20160129175834.GB19101@treble.redhat.com> <20160129142950.0f6a6e62@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20160129142950.0f6a6e62@gandalf.local.home> User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 29, 2016 at 02:29:50PM -0500, Steven Rostedt wrote: > On Fri, 29 Jan 2016 20:25:15 +0100 (CET) > Miroslav Benes wrote: > > > It is possible to achieve the same goal even with the notifiers. They are > > processed synchronously in complete_formation(). So we can put our klp > > hook after that, right? Or better, put it to load_module() after > > complete_formation() call. There is an error handling code even today > > (that is, parse_args() or mod_sysfs_setup() can fail). Moreover, we'll > > have a hook there with Jessica's relocation rework patch set. > > The problem with notifiers is that you don't know what is being called. > A function call directly in the code, where it will always be needed if > configured in, is a reasonable need to not use a notifier. > > Although, I have to admit, if live kernel patching is configured in, > it's not always needed to be called here, does it? With ftrace, the > call has to be done when ftrace is configured in regardless if tracing > is used or not. For live patching it actually does need to be called for every module. We need to check if any previously loaded patches have any modifications which affect the module. > > > > > But Steven's reasoning is convincing, so I'm all up for it. > > Great! > > -- Steve -- Josh