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=-3.0 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 0339EC43219 for ; Tue, 30 Apr 2019 15:08:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D1F5820835 for ; Tue, 30 Apr 2019 15:08:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726909AbfD3PIP (ORCPT ); Tue, 30 Apr 2019 11:08:15 -0400 Received: from mx2.suse.de ([195.135.220.15]:58536 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726050AbfD3PIN (ORCPT ); Tue, 30 Apr 2019 11:08:13 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 2AA3DAD31; Tue, 30 Apr 2019 15:08:12 +0000 (UTC) Date: Tue, 30 Apr 2019 17:08:11 +0200 From: Petr Mladek To: "Tobin C. Harding" Cc: Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Greg Kroah-Hartman , Joe Lawrence , live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] livepatch: Use correct kobject cleanup function Message-ID: <20190430150811.4hzhtz4w46o6numh@pathway.suse.cz> References: <20190430001534.26246-1-tobin@kernel.org> <20190430001534.26246-3-tobin@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190430001534.26246-3-tobin@kernel.org> User-Agent: NeoMutt/20170912 (1.9.0) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 2019-04-30 10:15:34, Tobin C. Harding wrote: > The correct cleanup function after a call to kobject_init_and_add() has > succeeded is kobject_del() _not_ kobject_put(). kobject_del() calls > kobject_put(). Really? I see only kobject_put(kobj->parent) in kobject_del. It decreases a reference of the _parent_ object and not the given one. Also the section "Kobject removal" in Documentation/kobject.txt says that kobject_del() is for two-stage removal. kobject_put() still needs to get called at a later time. IMHO, this patch causes that kobject_put() would never get called. That said, we could probably make the removal a bit cleaner by using kobject_del() in klp_free_patch_start() and kobject_put() in klp_free_patch_finish(). But I have to think more about it. Best Regards, Petr