From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751949Ab2GUIGz (ORCPT ); Sat, 21 Jul 2012 04:06:55 -0400 Received: from 93-97-173-237.zone5.bethere.co.uk ([93.97.173.237]:51332 "EHLO tim.rpsys.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751119Ab2GUIGt (ORCPT ); Sat, 21 Jul 2012 04:06:49 -0400 X-Greylist: delayed 1987 seconds by postgrey-1.27 at vger.kernel.org; Sat, 21 Jul 2012 04:06:49 EDT Message-ID: <1342856010.21788.47.camel@ted> Subject: Re: sysfs permissions on dynamic attributes (led delay_on and delay_off) From: Richard Purdie To: Greg KH Cc: Colin Cross , lkml , Bryan Wu Date: Sat, 21 Jul 2012 08:33:30 +0100 In-Reply-To: <20120721040816.GA7313@kroah.com> References: <20120721040816.GA7313@kroah.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.2- Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2012-07-20 at 21:08 -0700, Greg KH wrote: > On Fri, Jul 20, 2012 at 05:46:14PM -0700, Colin Cross wrote: > > I'm trying to use the standard ledtrig-timer.c code to handle led > > blinking for notifications on an Android device, and I'm hitting some > > issues with setting permissions on the dynamically created delay_on > > and delay_off attributes. For most sysfs files, we have userspace > > uevent parser that watches for device add notifications and > > chowns/chmods attributes. This doesn't work for delay_on and > > delay_off, because they are created later, when "timer" is written to > > the trigger attribute. There is no uevent when the new files are > > created, and sysfs doesn't support inotify, so I don't see any way to > > receive an event to set the permissions. This issue exists any time > > that device_create_file is called after device_add. > > > > What is the appropriate way to get an event to set the permissions? > > Add inotify support for sysfs file creation? Send a KOBJ_CHANGE > > uevent in device_create_file? > > No. > > > Send a KOBJ_CHANGE uevent from the driver after calling > > device_create_file? > > Yes. > > > Dynamically create a timer device under /sys/class/leds/ so a new > > add uevent gets sent? > > Ick. > > > Promote blinking to be a core led feature instead of a trigger, so the > > files are always present? > > That's the best thing, why not just do that? This implies we should make every trigger a core led feature and effectively do away with triggers. I'm not sure that makes sense. Cheers, Richard