From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753500AbdDKLbm (ORCPT ); Tue, 11 Apr 2017 07:31:42 -0400 Received: from mx2.suse.de ([195.135.220.15]:36209 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752291AbdDKLbi (ORCPT ); Tue, 11 Apr 2017 07:31:38 -0400 Date: Tue, 11 Apr 2017 13:31:33 +0200 (CEST) From: Miroslav Benes To: Petr Mladek cc: Josh Poimboeuf , Jessica Yu , Jiri Kosina , linux-kernel@vger.kernel.org, live-patching@vger.kernel.org Subject: Re: [PATCH] livepatch: Cancel transition a safe way for immediate patches In-Reply-To: <1491908868-27766-1-git-send-email-pmladek@suse.com> Message-ID: References: <1491908868-27766-1-git-send-email-pmladek@suse.com> User-Agent: Alpine 2.20 (LSU 67 2015-01-07) 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, 11 Apr 2017, Petr Mladek wrote: > klp_init_transition() does not set func->transition for immediate patches. > Then klp_ftrace_handler() could use the new code immediately. As a result, > it is not safe to put the livepatch module in klp_cancel_transition(). > > This patch reverts most of the last minute changes klp_cancel_transition(). > It keeps the warning about a misuse because it still makes sense. > > Signed-off-by: Petr Mladek > --- > Hi, > > I am afraid that Mirek was not right in the mail > https://lkml.kernel.org/r/alpine.LSU.2.20.1702161504020.16310@pobox.suse.cz > IMHO, it is not safe to put the module when the immediate > patch cannot be applied. > > Best Regards, > Petr You're right, Petr. Thanks for fixing my fault. If needed, we could still follow the idea - set func->transition even for immediate patches/funcs. But for now, removing the code is the best. Acked-by: Miroslav Benes Jiri, this (obviously) needs to go to 4.12 with the patch set... Miroslav > kernel/livepatch/transition.c | 20 -------------------- > 1 file changed, 20 deletions(-) > > diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c > index 2de09e0c4e5c..adc0cc64aa4b 100644 > --- a/kernel/livepatch/transition.c > +++ b/kernel/livepatch/transition.c > @@ -120,31 +120,11 @@ static void klp_complete_transition(void) > */ > void klp_cancel_transition(void) > { > - struct klp_patch *patch = klp_transition_patch; > - struct klp_object *obj; > - struct klp_func *func; > - bool immediate_func = false; > - > if (WARN_ON_ONCE(klp_target_state != KLP_PATCHED)) > return; > > klp_target_state = KLP_UNPATCHED; > klp_complete_transition(); > - > - /* > - * In the enable error path, even immediate patches can be safely > - * removed because the transition hasn't been started yet. > - * > - * klp_complete_transition() doesn't have a module_put() for immediate > - * patches, so do it here. > - */ > - klp_for_each_object(patch, obj) > - klp_for_each_func(obj, func) > - if (func->immediate) > - immediate_func = true; > - > - if (patch->immediate || immediate_func) > - module_put(patch->mod); > } > > /* > -- > 1.8.5.6 >