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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 C4B43C433DF for ; Sun, 24 May 2020 13:28:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 95AE720823 for ; Sun, 24 May 2020 13:28:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590326896; bh=gJTSLYRW+2rx99s8hbfszTFJABJKrpxA1GXRlTnBwO0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=d9TCJeLDcMBhloBsPiQoutCBkEdU0HsJdzrFAiMB0WseERE2VjKdNL3BS85LMID4q 6DqhlQXbMGa/XJtoxRWnjhD1NxwNba5ztv6z/ZpME1l86nebUyiECPQpkwNsQhPIPx bVoAFNbzdHZFE6heeK8piGR0t5nAExOIXAAzIzzM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729361AbgEXN2Q (ORCPT ); Sun, 24 May 2020 09:28:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:32806 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725873AbgEXN2P (ORCPT ); Sun, 24 May 2020 09:28:15 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 32C04207FB; Sun, 24 May 2020 13:28:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590326894; bh=gJTSLYRW+2rx99s8hbfszTFJABJKrpxA1GXRlTnBwO0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=epBMyA7oX3D69xEByPAPRLqnjd6WkI6JmL87hss1ZCnPkhShoIXJvJmYB85YRxAYF P4gztPr99Aniu3f7+9vw84T5xLqRkIo+QQwbkq+nxCVRKLmbPmmWEFDXtfEexq4VRC n3RzXD+qUgTvOZWpGfjhQA9ikYAWRS8ogiL1ivZw= Date: Sun, 24 May 2020 15:28:12 +0200 From: Greg Kroah-Hartman To: Randy Dunlap Cc: Heikki Krogerus , linux-kernel@vger.kernel.org, Naresh Kamboju , kernel test robot , Brendan Higgins , "Rafael J. Wysocki" Subject: Re: [PATCH] kobject: Make sure the parent does not get released before its children Message-ID: <20200524132812.GA2401@kroah.com> References: <20200513151840.36400-1-heikki.krogerus@linux.intel.com> <20200523153643.GA226270@kroah.com> <7a5e4740-8099-ef70-776f-0d92ce84ab3d@infradead.org> <20200524125727.GA2430@kroah.com> <20200524131405.GA24073@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200524131405.GA24073@kroah.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, May 24, 2020 at 03:14:05PM +0200, Greg Kroah-Hartman wrote: > On Sun, May 24, 2020 at 02:57:27PM +0200, Greg Kroah-Hartman wrote: > > On Sat, May 23, 2020 at 08:44:06AM -0700, Randy Dunlap wrote: > > > On 5/23/20 8:36 AM, Greg Kroah-Hartman wrote: > > > > On Wed, May 13, 2020 at 06:18:40PM +0300, Heikki Krogerus wrote: > > > >> In the function kobject_cleanup(), kobject_del(kobj) is > > > >> called before the kobj->release(). That makes it possible to > > > >> release the parent of the kobject before the kobject itself. > > > >> > > > >> To fix that, adding function __kboject_del() that does > > > >> everything that kobject_del() does except release the parent > > > >> reference. kobject_cleanup() then calls __kobject_del() > > > >> instead of kobject_del(), and separately decrements the > > > >> reference count of the parent kobject after kobj->release() > > > >> has been called. > > > >> > > > >> Reported-by: Naresh Kamboju > > > >> Reported-by: kernel test robot > > > >> Fixes: 7589238a8cf3 ("Revert "software node: Simplify software_node_release() function"") > > > >> Suggested-by: "Rafael J. Wysocki" > > > >> Signed-off-by: Heikki Krogerus > > > >> Reviewed-by: Rafael J. Wysocki > > > >> Reviewed-by: Brendan Higgins > > > >> Tested-by: Brendan Higgins > > > >> Acked-by: Randy Dunlap > > > >> --- > > > >> lib/kobject.c | 30 ++++++++++++++++++++---------- > > > >> 1 file changed, 20 insertions(+), 10 deletions(-) > > > > > > > > Stepping back, now that it turns out this patch causes more problems > > > > than it fixes, how is everyone reproducing the original crash here? > > > > > > Just load lib/test_printf.ko and boom! > > > > Thanks, that helps. > > > > Ok, in messing around with the kobject core more, originally we thought > > this was an issue of the kobject uevent happening for the parent pointer > > (when the parent was invalid). so, moving things around some more, and > > now I'm crashing in software_node_release() when we are trying to access > > swnode->parent->child_ids as parent is invalid there. > > > > So I feel like this is a swnode bug, or a use of swnode in a way it > > shouldn't be that the testing framework is exposing somehow. > > > > Let me dig deeper... > > Ah, ick, static software nodes trying to be cleaned up in the totally > wrong order. You can't just try to randomly clean up a kobject anywhere > in the middle of the hierarchy, that's flat out not going to work > properly. let me unwind it... Ok, the patch below fixes the test, there's not really anything wrong with the kobject core, except maybe the kobject uevent for removal, which I'll send a patch for. I'll write these up as a real set of patches after a bit. thanks, greg k-h diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c index de8d3543e8fe..34bc2bbb3ada 100644 --- a/drivers/base/swnode.c +++ b/drivers/base/swnode.c @@ -715,14 +715,10 @@ EXPORT_SYMBOL_GPL(software_node_register_nodes); */ void software_node_unregister_nodes(const struct software_node *nodes) { - struct swnode *swnode; int i; - for (i = 0; nodes[i].name; i++) { - swnode = software_node_to_swnode(&nodes[i]); - if (swnode) - fwnode_remove_software_node(&swnode->fwnode); - } + for (i = 0; nodes[i].name; i++) + software_node_unregister(&nodes[i]); } EXPORT_SYMBOL_GPL(software_node_unregister_nodes); @@ -741,6 +737,20 @@ int software_node_register(const struct software_node *node) } EXPORT_SYMBOL_GPL(software_node_register); +/** + * software_node_unregister - Unregister static software node + * @node: The software node to be unregistered + */ +void software_node_unregister(const struct software_node *node) +{ + struct swnode *swnode; + + swnode = software_node_to_swnode(node); + if (swnode) + fwnode_remove_software_node(&swnode->fwnode); +} +EXPORT_SYMBOL_GPL(software_node_unregister); + struct fwnode_handle * fwnode_create_software_node(const struct property_entry *properties, const struct fwnode_handle *parent) diff --git a/include/linux/property.h b/include/linux/property.h index d86de017c689..0d4099b4ce1f 100644 --- a/include/linux/property.h +++ b/include/linux/property.h @@ -441,6 +441,7 @@ int software_node_register_nodes(const struct software_node *nodes); void software_node_unregister_nodes(const struct software_node *nodes); int software_node_register(const struct software_node *node); +void software_node_unregister(const struct software_node *node); int software_node_notify(struct device *dev, unsigned long action); diff --git a/lib/test_printf.c b/lib/test_printf.c index 6b1622f4d7c2..b320c733af70 100644 --- a/lib/test_printf.c +++ b/lib/test_printf.c @@ -637,7 +637,9 @@ static void __init fwnode_pointer(void) test(second_name, "%pfwP", software_node_fwnode(&softnodes[1])); test(third_name, "%pfwP", software_node_fwnode(&softnodes[2])); - software_node_unregister_nodes(softnodes); + software_node_unregister(&softnodes[2]); + software_node_unregister(&softnodes[1]); + software_node_unregister(&softnodes[0]); } static void __init