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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 12E66C433DB for ; Mon, 11 Jan 2021 14:21:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DEAF822473 for ; Mon, 11 Jan 2021 14:21:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731265AbhAKOVe (ORCPT ); Mon, 11 Jan 2021 09:21:34 -0500 Received: from mail.kernel.org ([198.145.29.99]:36558 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727240AbhAKOVd (ORCPT ); Mon, 11 Jan 2021 09:21:33 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9DC5A2242A; Mon, 11 Jan 2021 14:20:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1610374852; bh=lRhzRu5y4+MceKt6vK/qDXTv1oaK7iwXlndeq3cc600=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=SFji115mDcl1gtX+XC2CFqcklpyblJlnLg+sAOKBIybrr5ATHHjfg0hOlH8GzVpHA /aOkR5ICzC35xufnLjxzu15zrIPs/jbwmvSSr9quMYAUHIluDaWAnnGxdK+Nh5tbpm H4z5KvSLtFKg4J0kv/2o3RPFs7XcNe6Kfot//k7/pfDPgittnqfYxacFfTsX9qVzNH rGV8CBpEaZ7aQHgnT5VLYxjfRQ3DsKHnJYKEDORm7D2N6Ospcmv0V++YAZe42FaFcG KIdOgaEEAS+G22dVfnYFAYiBAjiOZb6EsPRfU4Mi70ce/c7sXpSZxC9eTOxyYf9HAT hUQ/RuFVFha4Q== Date: Mon, 11 Jan 2021 15:20:48 +0100 From: Jessica Yu To: Adam Zabrocki Cc: Nicolas Morey-Chaisemartin , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Solar Designer Subject: Re: Linux Kernel module notification bug Message-ID: <20210111142048.GA27038@linux-8ccs> References: <20210110175401.GB32505@pi3.com.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20210110175401.GB32505@pi3.com.pl> X-OS: Linux linux-8ccs 4.12.14-lp150.12.28-default x86_64 User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org +++ Adam Zabrocki [10/01/21 18:54 +0100]: >Hello, > >I believe that the following commit does introduce a gentle "functionality >bug": > >"module: delay kobject uevent until after module init call": >https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/kernel/module.c?id=38dc717e97153e46375ee21797aa54777e5498f3 > >The official Linux Kernel API for the kernel module activities notification has >been divided based on the readiness 'stage' for such module. We have the >following stages: > > MODULE_STATE_LIVE, /* Normal state. */ > MODULE_STATE_COMING, /* Full formed, running module_init. */ > MODULE_STATE_GOING, /* Going away. */ > MODULE_STATE_UNFORMED, /* Still setting it up. */ > >LIVE means that the kernel module is correctly running and all initialization >work has been already done. Otherwise, we have event 'COMING' or 'UNFORMED'. > >In the described commit, creation of the KOBJECT has been moved after invoking >a notficiation of the newly formed kernel module state (LIVE). That's somehow >inconsistent from my understanding of the kernel modules notifiers logic. >Creation of the new objects (like KOBJ) should be done before notification of >the stage LIVE is invoked. I'm confused. We're not creating any kobjects here. That is all done in mod_sysfs_setup(), which is called while the module is still COMING. What that commit does is delay telling userspace about the module (specifically, systemd/udev) until the module is basically ready. Systemd was basically receiving the uevent too early, before the module has initialized, hence we decided to delay the uevent [1]. >This commit breaks some of the projects that rely on the LIVE notification to >monitor when the newly loaded module is ready. Hm, could you please explain specifically what is the issue you're seeing? What projects is it breaking? Thanks, Jessica [1] https://github.com/systemd/systemd/issues/17586