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=-24.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 D5B60C43332 for ; Wed, 30 Dec 2020 13:05:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BD4B022227 for ; Wed, 30 Dec 2020 13:05:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727648AbgL3NFt (ORCPT ); Wed, 30 Dec 2020 08:05:49 -0500 Received: from mail.kernel.org ([198.145.29.99]:54530 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727543AbgL3NFm (ORCPT ); Wed, 30 Dec 2020 08:05:42 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id C6E3C22472; Wed, 30 Dec 2020 13:04:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1609333493; bh=N18w8azLFE3tES6PO7GvY6OxDdr+XvQtTPp93v2Z9CU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bjYppR8LBB0D10FMQbUGOagGZMkoax92Nt/rFbxFN2pwuujr3W2UlHL0r8O4vZOPk 8wU+E2dyyNoaahPGWAqt8mZFcYMMTNhfDftnZbDGLqA4UArSHZCZ+Nppd1Jl2W1pdZ anjempBkHy2GaAWpp92j421O7N4iYC3bkFBqC5j7EdYZ47R9wQEqzWjTydjjIA8nap e+zXCE1yMh3pFczFYY7iRgfusrOIXCc1aco0ipuBb5Q6vjgb3ZyuSPEvcLFWbwJKFr Py7QcvKs5xzyBVB8mC80/VGqD6f7BdXBPXIazKj1ueoCDW5C0HFvHocyHAn5hPEOhz OBWMeNU2hQZ9A== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Jessica Yu , Greg Kroah-Hartman , Nicolas Morey-Chaisemartin , Sasha Levin Subject: [PATCH AUTOSEL 4.9 5/5] module: delay kobject uevent until after module init call Date: Wed, 30 Dec 2020 08:04:47 -0500 Message-Id: <20201230130447.3637694-5-sashal@kernel.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20201230130447.3637694-1-sashal@kernel.org> References: <20201230130447.3637694-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jessica Yu [ Upstream commit 38dc717e97153e46375ee21797aa54777e5498f3 ] Apparently there has been a longstanding race between udev/systemd and the module loader. Currently, the module loader sends a uevent right after sysfs initialization, but before the module calls its init function. However, some udev rules expect that the module has initialized already upon receiving the uevent. This race has been triggered recently (see link in references) in some systemd mount unit files. For instance, the configfs module creates the /sys/kernel/config mount point in its init function, however the module loader issues the uevent before this happens. sys-kernel-config.mount expects to be able to mount /sys/kernel/config upon receipt of the module loading uevent, but if the configfs module has not called its init function yet, then this directory will not exist and the mount unit fails. A similar situation exists for sys-fs-fuse-connections.mount, as the fuse sysfs mount point is created during the fuse module's init function. If udev is faster than module initialization then the mount unit would fail in a similar fashion. To fix this race, delay the module KOBJ_ADD uevent until after the module has finished calling its init routine. References: https://github.com/systemd/systemd/issues/17586 Reviewed-by: Greg Kroah-Hartman Tested-By: Nicolas Morey-Chaisemartin Signed-off-by: Jessica Yu Signed-off-by: Sasha Levin --- kernel/module.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index a106801f1582b..0219301b6109c 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -1762,7 +1762,6 @@ static int mod_sysfs_init(struct module *mod) if (err) mod_kobject_put(mod); - /* delay uevent until full sysfs population */ out: return err; } @@ -1796,7 +1795,6 @@ static int mod_sysfs_setup(struct module *mod, add_sect_attrs(mod, info); add_notes_attrs(mod, info); - kobject_uevent(&mod->mkobj.kobj, KOBJ_ADD); return 0; out_unreg_param: @@ -3427,6 +3425,9 @@ static noinline int do_init_module(struct module *mod) blocking_notifier_call_chain(&module_notify_list, MODULE_STATE_LIVE, mod); + /* Delay uevent until module has finished its init routine */ + kobject_uevent(&mod->mkobj.kobj, KOBJ_ADD); + /* * We need to finish all async code before the module init sequence * is done. This has potential to deadlock. For example, a newly -- 2.27.0