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=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 42F20C11D0C for ; Thu, 20 Feb 2020 19:51:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 252B8206F4 for ; Thu, 20 Feb 2020 19:51:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729011AbgBTTvw (ORCPT ); Thu, 20 Feb 2020 14:51:52 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:55785 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728448AbgBTTvw (ORCPT ); Thu, 20 Feb 2020 14:51:52 -0500 Received: from ip5f5bf7ec.dynamic.kabel-deutschland.de ([95.91.247.236] helo=wittgenstein) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1j4rrS-0006UR-54; Thu, 20 Feb 2020 19:51:50 +0000 Date: Thu, 20 Feb 2020 20:51:49 +0100 From: Christian Brauner To: Greg Kroah-Hartman 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 v3 2/9] sysfs: add sysfs_link_change_owner() Message-ID: <20200220195149.xha7jltmfzs3xs7g@wittgenstein> References: <20200218162943.2488012-1-christian.brauner@ubuntu.com> <20200218162943.2488012-3-christian.brauner@ubuntu.com> <20200220111443.GD3374196@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200220111443.GD3374196@kroah.com> Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Thu, Feb 20, 2020 at 12:14:43PM +0100, Greg Kroah-Hartman wrote: > On Tue, Feb 18, 2020 at 05:29:36PM +0100, Christian Brauner wrote: > > Add a helper to change the owner of a sysfs link. > > 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 > > --- > > /* v2 */ > > - Greg Kroah-Hartman : > > - Add comment how ownership of sysfs object is changed. > > > > /* v3 */ > > - Greg Kroah-Hartman : > > - Add explicit uid/gid parameters. > > --- > > fs/sysfs/file.c | 40 ++++++++++++++++++++++++++++++++++++++++ > > include/linux/sysfs.h | 10 ++++++++++ > > 2 files changed, 50 insertions(+) > > > > diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c > > index 32bb04b4d9d9..df5107d7b3fd 100644 > > --- a/fs/sysfs/file.c > > +++ b/fs/sysfs/file.c > > @@ -570,6 +570,46 @@ static int internal_change_owner(struct kernfs_node *kn, struct kobject *kobj, > > return kernfs_setattr(kn, &newattrs); > > } > > > > +/** > > + * sysfs_link_change_owner - change owner of a link. > > + * @kobj: object of the kernfs_node the symlink is located in. > > + * @targ: object of the kernfs_node the symlink points to. > > + * @name: name of the link. > > + * @kuid: new owner's kuid > > + * @kgid: new owner's kgid > > + */ > > +int sysfs_link_change_owner(struct kobject *kobj, struct kobject *targ, > > + const char *name, kuid_t kuid, kgid_t kgid) > > +{ > > + struct kernfs_node *parent, *kn = NULL; > > + int error; > > + > > + if (!kobj) > > + parent = sysfs_root_kn; > > + else > > + parent = kobj->sd; > > I don't understand this, why would (!kobj) ever be a valid situation? Yeah, a caller could just pass in "sysfs_root_kn" itself if they for some reason needed to. > > > + if (!targ->state_in_sysfs) > > + return -EINVAL; > > Should you also check kobj->state_in_sysfs as well? Probably. I'll take a closer look now. Thanks! Christian