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,URIBL_BLOCKED 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 09557C433E1 for ; Tue, 16 Jun 2020 17:11:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E240720C09 for ; Tue, 16 Jun 2020 17:11:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592327476; bh=F3Z7ZE9ciwRV9Oco1l7sAqIS7v5q6e0MfPYwzEMo3oA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=egOz8opdhwd3yjhPcONBKXLMU51+r7HLE9yDjd98c+RjhUNxWxI7aEvDYQ26uTiU+ ScSlglMoeIcN9hpYHSOd5SNKyOnTEYJ9h5tq1Miqu1g3feorzHxq2eyE37ZjtxGq1s lziKHbAT3F8b3OuBxYJzULJZM2kwIs7NnxHhYK5U= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730729AbgFPRLP (ORCPT ); Tue, 16 Jun 2020 13:11:15 -0400 Received: from mail.kernel.org ([198.145.29.99]:59758 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730125AbgFPRLP (ORCPT ); Tue, 16 Jun 2020 13:11:15 -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 1F1D720B1F; Tue, 16 Jun 2020 17:11:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592327474; bh=F3Z7ZE9ciwRV9Oco1l7sAqIS7v5q6e0MfPYwzEMo3oA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=AQuWzJsxKgUuhQ/SRB2PZTHlF0nzNvYpQB8XpTvKbePZRm7KW9ISv3Mveuy03LCDV n1gJY2bwLucKXXAydX3WGBQgp1UqvppOfTMW8HN3qa8iU5SsJg6OvTLbPDs+rqFIii KC1nNTMP7Z9r9c3zQXfU4rZE3FsD2nJRR+KAvXeE= Date: Tue, 16 Jun 2020 19:11:07 +0200 From: Greg Kroah-Hartman To: "Rafael J. Wysocki" Cc: Linux Kernel Mailing List , Stable , Naresh Kamboju , kernel test robot , Heikki Krogerus , "Rafael J. Wysocki" , Brendan Higgins , Randy Dunlap , Sasha Levin Subject: Re: [PATCH 5.6 041/161] kobject: Make sure the parent does not get released before its children Message-ID: <20200616171107.GA4161772@kroah.com> References: <20200616153106.402291280@linuxfoundation.org> <20200616153108.333633206@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 16, 2020 at 07:05:44PM +0200, Rafael J. Wysocki wrote: > On Tue, Jun 16, 2020 at 5:50 PM Greg Kroah-Hartman > wrote: > > > > From: Heikki Krogerus > > > > [ Upstream commit 4ef12f7198023c09ad6d25b652bd8748c965c7fa ] > > > > 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 > > Link: https://lore.kernel.org/r/20200513151840.36400-1-heikki.krogerus@linux.intel.com > > Cc: stable > > Signed-off-by: Greg Kroah-Hartman > > Signed-off-by: Sasha Levin > > --- > > lib/kobject.c | 30 ++++++++++++++++++++---------- > > 1 file changed, 20 insertions(+), 10 deletions(-) > > > > diff --git a/lib/kobject.c b/lib/kobject.c > > index 83198cb37d8d..2bd631460e18 100644 > > --- a/lib/kobject.c > > +++ b/lib/kobject.c > > @@ -599,14 +599,7 @@ int kobject_move(struct kobject *kobj, struct kobject *new_parent) > > } > > EXPORT_SYMBOL_GPL(kobject_move); > > > > -/** > > - * kobject_del() - Unlink kobject from hierarchy. > > - * @kobj: object. > > - * > > - * This is the function that should be called to delete an object > > - * successfully added via kobject_add(). > > - */ > > -void kobject_del(struct kobject *kobj) > > +static void __kobject_del(struct kobject *kobj) > > { > > struct kernfs_node *sd; > > const struct kobj_type *ktype; > > @@ -625,9 +618,23 @@ void kobject_del(struct kobject *kobj) > > > > kobj->state_in_sysfs = 0; > > kobj_kset_leave(kobj); > > - kobject_put(kobj->parent); > > kobj->parent = NULL; > > } > > + > > +/** > > + * kobject_del() - Unlink kobject from hierarchy. > > + * @kobj: object. > > + * > > + * This is the function that should be called to delete an object > > + * successfully added via kobject_add(). > > + */ > > +void kobject_del(struct kobject *kobj) > > +{ > > + struct kobject *parent = kobj->parent; > > + > > + __kobject_del(kobj); > > + kobject_put(parent); > > +} > > EXPORT_SYMBOL(kobject_del); > > > > /** > > @@ -663,6 +670,7 @@ EXPORT_SYMBOL(kobject_get_unless_zero); > > */ > > static void kobject_cleanup(struct kobject *kobj) > > { > > + struct kobject *parent = kobj->parent; > > struct kobj_type *t = get_ktype(kobj); > > const char *name = kobj->name; > > > > @@ -684,7 +692,7 @@ static void kobject_cleanup(struct kobject *kobj) > > if (kobj->state_in_sysfs) { > > pr_debug("kobject: '%s' (%p): auto cleanup kobject_del\n", > > kobject_name(kobj), kobj); > > - kobject_del(kobj); > > + __kobject_del(kobj); > > } > > > > if (t && t->release) { > > @@ -698,6 +706,8 @@ static void kobject_cleanup(struct kobject *kobj) > > pr_debug("kobject: '%s': free name\n", name); > > kfree_const(name); > > } > > + > > + kobject_put(parent); > > This is known incorrect, because that should only be done if the > __kobject_del() above has run. > > Also this commit has been reverted from the mainline. Argh, I should have caught this, my fault, sorry, I'll go drop it. > I have posted a fixed replacement for it with no response whatever so far: > > https://lore.kernel.org/lkml/1908555.IiAGLGrh1Z@kreacher/ It's been the merge window, I couldn't do anything until Monday :) It's in my queue, give me a chance to catch up... thanks, greg k-h