From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E20F3C65BAE for ; Thu, 13 Dec 2018 22:46:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6654020851 for ; Thu, 13 Dec 2018 22:46:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6654020851 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728304AbeLMWqd (ORCPT ); Thu, 13 Dec 2018 17:46:33 -0500 Received: from mx1.redhat.com ([209.132.183.28]:38646 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726457AbeLMWqc (ORCPT ); Thu, 13 Dec 2018 17:46:32 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 57392300207A; Thu, 13 Dec 2018 22:46:32 +0000 (UTC) Received: from treble (ovpn-120-195.rdu2.redhat.com [10.10.120.195]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D829760FE5; Thu, 13 Dec 2018 22:46:27 +0000 (UTC) Date: Thu, 13 Dec 2018 16:46:25 -0600 From: Josh Poimboeuf To: Petr Mladek Cc: Jiri Kosina , Miroslav Benes , Jason Baron , Joe Lawrence , Evgenii Shatokhin , live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v14 05/11] livepatch: Simplify API by removing registration step Message-ID: <20181213224625.65o77z75u4njocnp@treble> References: <20181129094431.7801-1-pmladek@suse.com> <20181129094431.7801-6-pmladek@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20181129094431.7801-6-pmladek@suse.com> User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.47]); Thu, 13 Dec 2018 22:46:32 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 29, 2018 at 10:44:25AM +0100, Petr Mladek wrote: > @@ -309,40 +297,33 @@ static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr, > > mutex_lock(&klp_mutex); > > - if (!klp_is_patch_registered(patch)) { > - /* > - * Module with the patch could either disappear meanwhile or is > - * not properly initialized yet. > - */ > - ret = -EINVAL; > - goto err; > - } > - > if (patch->enabled == enabled) { > /* already in requested state */ > ret = -EINVAL; > - goto err; > + goto out; > } > > - if (patch == klp_transition_patch) { > + /* > + * Allow to reverse a pending transition in both ways. It might be > + * necessary to complete the transition without forcing and breaking > + * the system integrity. > + * > + * Do not allow to re-enable a disabled patch because this interface > + * is being destroyed. > + */ > + if (patch == klp_transition_patch) > klp_reverse_transition(); > - } else if (enabled) { > - ret = __klp_enable_patch(patch); > - if (ret) > - goto err; > - } else { > + else if (!enabled) > ret = __klp_disable_patch(patch); > - if (ret) > - goto err; > - } > + else > + ret = -EINVAL; Now that we can't re-enable a patch, I wonder if we really need both the 'patch->enabled' and 'klp_target_state' variables? A patch is now always enabled, unless it's in transition, in which case its 'enabled' state is the same as 'klp_target_state'. For example I wonder if we could get rid of 'klp_target_state', since it should be the same as 'klp_transition_patch->enabled'. Or alternatively we could get rid of 'patch->enabled', since it should be the same as patch == klp_transition_patch ? klp_target_state : true Of course this could be a follow-on cleanup patch, which could be done in the future, so as not to hold up the merging of these patches anymore. -- Josh