Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752366AbbKPMVt (ORCPT ); Mon, 16 Nov 2015 07:21:49 -0500 Received: from mx2.suse.de ([195.135.220.15]:57660 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751606AbbKPMVp (ORCPT ); Mon, 16 Nov 2015 07:21:45 -0500 Date: Mon, 16 Nov 2015 13:21:44 +0100 (CET) From: Miroslav Benes To: Jessica Yu cc: Josh Poimboeuf , Petr Mladek , Rusty Russell , Seth Jennings , Jiri Kosina , Vojtech Pavlik , linux-api@vger.kernel.org, live-patching@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: module: save load_info for livepatch modules In-Reply-To: <20151114020950.GA21414@packer-debian-8-amd64.digitalocean.com> Message-ID: References: <1447130755-17383-3-git-send-email-jeyu@redhat.com> <20151112053228.GD30025@packer-debian-8-amd64.digitalocean.com> <20151112102404.GL4431@pathway.suse.cz> <20151112150345.GT2599@pathway.suse.cz> <20151112170501.GD4038@treble.hsd1.ky.comcast.net> <20151112221750.GA13513@packer-debian-8-amd64.digitalocean.com> <20151114020950.GA21414@packer-debian-8-amd64.digitalocean.com> User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) 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 Content-Length: 2248 Lines: 55 On Fri, 13 Nov 2015, Jessica Yu wrote: > +++ Miroslav Benes [13/11/15 13:56 +0100]: > > On Fri, 13 Nov 2015, Miroslav Benes wrote: > > > > > I agree this seems like the best approach. So if we preserve > > > mod_arch_syminfo (in case of s390) we should free it not in > > > module_finalize, but somewhere in free_module... where > > > module_arch_cleanup() is called... and also module_arch_freeing_init() is > > > called there too. And what you find there for s390 is > > > > > > vfree(mod->arch.syminfo); > > > mod->arch.syminfo = NULL; > > > > > > Well, it does nothing here, because mod->arch.syminfo is already NULL. It > > > was freed in module_finalize. So we can even remove this code from > > > module_finalize and all should be fine. At least for s390. > > > > Which is not true because module_arch_freeing_init is also called from > > do_init_module, called from load_module. So we should move it to > > module_arch_cleanup. > > > > That code is like a maze without Ariadne's thread. > > Heh, I agree with that sentiment. > > I am slightly confused about the s390 code, and whether the authors > originally intended for that double vfree() to happen in both > module_finalize() and module_arch_freeing_init() (called from > do_init_module). Seems like a mistake. If module load succeeds, > do_init_module calls module_arch_freeing_init(). And if load_module > fails halfway through, both module_deallocate() and free_module() will > also call module_arch_freeing_init(). It seems like the authors are aware of this. At least the authors of general module code :). See comment in free_module() /* This may be NULL, but that's OK */ It is ok, because vfree checks if the pointer is NULL. > I feel like that vfree should > only happen once in module_arch_freeing_init() and not in > module_finalize(). If we can remove the double vfree() code from > module_finalize(), we can copy the mod_arch_specific safely before the > call to do_init_module(). Yes, I think so. Miroslav -- 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/