From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751786AbbAPWVk (ORCPT ); Fri, 16 Jan 2015 17:21:40 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:47942 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750968AbbAPWVk (ORCPT ); Fri, 16 Jan 2015 17:21:40 -0500 Date: Fri, 16 Jan 2015 14:21:39 -0800 From: Greg Kroah-Hartman To: Vivien Didelot Cc: linux-kernel@vger.kernel.org, kernel@savoirfairelinux.com Subject: Re: [PATCH] sysfs: group: allow is_visible to drop permissions Message-ID: <20150116222139.GB512@kroah.com> References: <1421443750-12935-1-git-send-email-vivien.didelot@savoirfairelinux.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1421443750-12935-1-git-send-email-vivien.didelot@savoirfairelinux.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 16, 2015 at 04:29:10PM -0500, Vivien Didelot wrote: > Using the optional is_visible function, it is actually possible to > either hide an attribute, or add a new permission, but not remove one. What code wants to remove attributes? > This commit uses all the UGO bits returned by is_visible instead of > OR'ing them with the default attribute mode. > > Concretely, this allows a driver to use macros like DEVICE_ATTR_RW to > set the attribute show and store functions and remove the S_IWUSR > permission in is_visible if the implementation doesn't provide a setter. What bus wants to do this? > Signed-off-by: Vivien Didelot > --- > fs/sysfs/group.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) > > diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c > index 7d2a860..a8cfe03 100644 > --- a/fs/sysfs/group.c > +++ b/fs/sysfs/group.c > @@ -41,7 +41,7 @@ static int create_files(struct kernfs_node *parent, struct kobject *kobj, > > if (grp->attrs) { > for (i = 0, attr = grp->attrs; *attr && !error; i++, attr++) { > - umode_t mode = 0; > + umode_t mode = (*attr)->mode; > > /* > * In update mode, we're changing the permissions or > @@ -51,13 +51,15 @@ static int create_files(struct kernfs_node *parent, struct kobject *kobj, > if (update) > kernfs_remove_by_name(parent, (*attr)->name); > if (grp->is_visible) { > - mode = grp->is_visible(kobj, *attr, i); > - if (!mode) > + umode_t ugo = grp->is_visible(kobj, *attr, i); > + > + if (!(ugo & S_IRWXUGO)) > continue; > + > + mode = (mode & ~S_IRWXUGO) | (ugo & S_IRWXUGO); Please document what you are doing here in the code, it's not obvious at first glance. > } > error = sysfs_add_file_mode_ns(parent, *attr, false, > - (*attr)->mode | mode, > - NULL); > + mode, NULL); Any chance this is going to break existing code that isn't expecting this type of change in functionality? thanks, greg k-h