From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752731AbeB1NU0 (ORCPT ); Wed, 28 Feb 2018 08:20:26 -0500 Received: from mx2.suse.de ([195.135.220.15]:38680 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752267AbeB1NUZ (ORCPT ); Wed, 28 Feb 2018 08:20:25 -0500 Date: Wed, 28 Feb 2018 14:20:22 +0100 (CET) From: Miroslav Benes To: Joe Lawrence cc: live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, Josh Poimboeuf , Jessica Yu , Jiri Kosina , Petr Mladek , Jason Baron , Evgenii Shatokhin Subject: Re: [PATCH v0 2/3] livepatch: update documentation/samples for callbacks In-Reply-To: Message-ID: References: <1519421630-12025-1-git-send-email-joe.lawrence@redhat.com> <1519421630-12025-3-git-send-email-joe.lawrence@redhat.com> User-Agent: Alpine 2.21 (LSU 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 27 Feb 2018, Joe Lawrence wrote: > On 02/27/2018 07:36 AM, Miroslav Benes wrote: > > On Fri, 23 Feb 2018, Joe Lawrence wrote: > > > >> [ ... snip ... ] > >> > >> +If a livepatch is replaced by a cumulative patch, then only the > >> +callbacks belonging to the cumulative patch will be executed. This > >> +simplifies the livepatching core for it is the responsibility of the > >> +cumulative patch to safely revert whatever needs to be reverted. See > >> +Documentation/livepatch/cumulative.txt for more information on such > >> +patches. > > > > s/cumulative/atomic replace/ almost everywhere? > > > > 'Documentation/livepatch/cumulative.txt' should be > > 'Documentation/livepatch/cumulative-patches.txt' and we may rename it > > atomic-replace-patches.txt. I don't know. Cumulative patches forms a > > subset of atomic replace patches in my understanding. The feature itself > > is more general. Even if practically used for cumulative patches only. But > > it is for you and Petr to decide. > > Hi Miroslav, > > Thanks for reviewing! > > I guess I'm a little confused about the distinction here. > > I understood a "cumulative-patch" to mean that it would contain the sum > of all changes. So instead of this: > > patch 1 = A > + patch 2 = B > + patch 3 = C > ----------------------- > net = A + B + C > > We can group all of the changes together into a single cumulative-patch > for the same net effect: > > patch 1 = A -replaced by- > patch 2 = A + B -replaced by- > patch 3 = A + B + C Yes. > I assumed this would also mean to include any reverted changes as well. > So in the example above, if change C needed to be reverted, then: > > patch 4 = A + B > > and that would still be considered a "cumulative-patch". Ah, ok. This is where we differ. I didn't consider this to be a cumulative patch. But I understand your reasoning. Miroslav