Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752681AbaKGNWN (ORCPT ); Fri, 7 Nov 2014 08:22:13 -0500 Received: from mx1.redhat.com ([209.132.183.28]:55644 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752650AbaKGNWJ (ORCPT ); Fri, 7 Nov 2014 08:22:09 -0500 Date: Fri, 7 Nov 2014 07:22:03 -0600 From: Josh Poimboeuf To: Jiri Kosina Cc: Seth Jennings , Vojtech Pavlik , Steven Rostedt , live-patching@vger.kernel.org, kpatch@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] kernel: add support for live patching Message-ID: <20141107132203.GE4071@treble.redhat.com> References: <1415284748-14648-1-git-send-email-sjenning@redhat.com> <1415284748-14648-3-git-send-email-sjenning@redhat.com> <20141106162049.GA14689@cerebellum.variantweb.net> <20141107125016.GB4071@treble.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 07, 2014 at 02:13:37PM +0100, Jiri Kosina wrote: > On Fri, 7 Nov 2014, Josh Poimboeuf wrote: > > > > Also, lpc_create_object(), lpc_create_func(), lpc_create_patch(), > > > lpc_create_objects(), lpc_create_funcs(), ... they all are pretty much > > > alike, and are asking for some kind of unification ... perhaps iterator > > > for generic structure initialization? > > > > The allocation and initialization code is very simple and > > straightforward. I really don't see a problem there. > > This really boils down to the question I had in previous mail, whether > three-level hierarchy (patch->object->funcs), which is why there is a lot > of very alike initialization code, is not a bit over-designed. Oh sorry, I missed that point :-) See below. > > > > I am not also really fully convinced that we need the > > > patch->object->funcs abstraction hierarchy (which also contributes to > > > the structure allocation being rather a spaghetti copy/paste code) ... > > > wouldn't patch->funcs be suffcient, with the "object" being made just > > > a property of the function, for example? The patched object represents the module being patched (or "vmlinux"). It is much more than a property of the function. Multiple functions can be patched in the same object. There are several things we do on a per-object basis, including try_module_get(), deferred module patching (patching from the module notifier), and dynamic relocations. > > > > > > > Plus, I show that kernel/kgraft.c + kernel/kgraft_files.c is > > > > 906+193=1099. I'd say they are about the same size :) > > > > > > Which is still seem to me to be a ratio worth thinking about improving > > > :) > > > > Yes, this code doesn't have a consistency model, but it does have some > > other non-kGraft things like dynamic relocations, > > BTW we need to put those into arch/x86/ as they are unfortunately not > generic. But more on this later independently. > > > deferred module patching, > > FWIW kgraft supports that as well. > > > and a unified API. There's really no point in comparing lines of code. > > Oh, sure, I didn't mean that this is any kind of metrics that should be > taken too seriously at all. I was just expressing my surprise that > unification of the API would bring so much code that it makes the result > comparably sized to "the whole thing" :) > > Thanks, > > -- > Jiri Kosina > SUSE Labs -- Josh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/