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 D2EC5C2BA83 for ; Wed, 12 Feb 2020 13:18:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A63C22073C for ; Wed, 12 Feb 2020 13:18:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581513492; bh=9lC0NLLMXRwM/8N7YwMQM48/0FD5N7I+tSFUZTrgg8w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=IHSsAIUwyAXQRTvpW/nGB0hxruwA4LCfd/IAZ/Q4mgYXwLU1miQ8JHBEJTPi3NWta uVYFzvcF1kPxRdjcyjqBT+zImx2FB/cW5Z2DVWKyBz+OtIVQRiHOP5laKH9bdyOgOQ AZ+aHA7xkeNGrTXe5zyg4k2nSDRL/i8NYNacZ/io= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728021AbgBLNSM (ORCPT ); Wed, 12 Feb 2020 08:18:12 -0500 Received: from mail.kernel.org ([198.145.29.99]:45204 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725887AbgBLNSL (ORCPT ); Wed, 12 Feb 2020 08:18:11 -0500 Received: from localhost (unknown [209.37.97.194]) (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 4B4EF2073C; Wed, 12 Feb 2020 13:18:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581513489; bh=9lC0NLLMXRwM/8N7YwMQM48/0FD5N7I+tSFUZTrgg8w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=veYP90b3VCLa7J6+E0JrAnlQXvFD1YCR9D+Bhuba8wyocvmCOc7o8LpPSS/PcU5Dh i4W3vx+L/ssQ9OE1/qNgOz9rdzzzikiotkNEUjNu1vKWZceXFl7sgUlhBhpA9o5dM7 PLd8FL6mj5lUvo8XqCiEjLnynBKXMyt/o9nnFI3k= Date: Wed, 12 Feb 2020 05:18:08 -0800 From: Greg Kroah-Hartman To: Christian Brauner Cc: "David S. Miller" , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, "Rafael J. Wysocki" , Pavel Machek , Jakub Kicinski , Eric Dumazet , Stephen Hemminger , linux-pm@vger.kernel.org Subject: Re: [PATCH net-next 05/10] sysfs: add sysfs_change_owner() Message-ID: <20200212131808.GA1789899@kroah.com> References: <20200212104321.43570-1-christian.brauner@ubuntu.com> <20200212104321.43570-6-christian.brauner@ubuntu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200212104321.43570-6-christian.brauner@ubuntu.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 12, 2020 at 11:43:16AM +0100, Christian Brauner wrote: > Add a helper to change the owner of sysfs objects. Seems sane, but: > The ownership of a sysfs object is determined based on the ownership of > the corresponding kobject, i.e. only if the ownership of a kobject is > changed will this function change the ownership of the corresponding > sysfs entry. A "sysfs object" is a kobject. So I don't understand this sentance, sorry. > This function will be used to correctly account for kobject ownership > changes, e.g. when moving network devices between network namespaces. > > Signed-off-by: Christian Brauner > --- > fs/sysfs/file.c | 35 +++++++++++++++++++++++++++++++++++ > include/linux/sysfs.h | 6 ++++++ > 2 files changed, 41 insertions(+) > > diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c > index 6239d9584f0b..6a0fe88061fd 100644 > --- a/fs/sysfs/file.c > +++ b/fs/sysfs/file.c > @@ -642,3 +642,38 @@ int sysfs_file_change_owner(struct kobject *kobj, const char *name) > return error; > } > EXPORT_SYMBOL_GPL(sysfs_file_change_owner); > + > +/** > + * sysfs_change_owner - change owner of the given object. > + * @kobj: object. > + */ > +int sysfs_change_owner(struct kobject *kobj) What does this change the owner of the given object _to_? > +{ > + int error; > + const struct kobj_type *ktype; > + > + if (!kobj->state_in_sysfs) > + return -EINVAL; > + > + error = sysfs_file_change_owner(kobj, NULL); It passes NULL? > + if (error) > + return error; > + > + ktype = get_ktype(kobj); > + if (ktype) { > + struct attribute **kattr; > + > + for (kattr = ktype->default_attrs; kattr && *kattr; kattr++) { > + error = sysfs_file_change_owner(kobj, (*kattr)->name); > + if (error) > + return error; > + } > + > + error = sysfs_groups_change_owner(kobj, ktype->default_groups); > + if (error) > + return error; > + } > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(sysfs_change_owner); I can understand wanting to change owners/groups/whatever of existing sysfs objects and their files, but I can't figure out how to call this function to set the attribute I want to change. With only one parameter, how does this work? It guesses? :) thanks, greg k-h