From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757177Ab0ELTV0 (ORCPT ); Wed, 12 May 2010 15:21:26 -0400 Received: from cantor2.suse.de ([195.135.220.15]:51186 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757040Ab0ELTVZ (ORCPT ); Wed, 12 May 2010 15:21:25 -0400 Date: Wed, 12 May 2010 12:19:55 -0700 From: Greg KH To: Kay Sievers Cc: Anton Vorontsov , Daniel Mack , linux-kernel@vger.kernel.org, David Woodhouse , Alexey Starikovskiy , Len Brown , Mark Brown , Matt Reimer , Evgeniy Polyakov , Tejun Heo Subject: Re: [PATCH] Introduce {sysfs,device}_create_file_mode Message-ID: <20100512191955.GA30861@suse.de> References: <1273595926-26249-1-git-send-email-daniel@caiaq.de> <20100511174708.GA26777@oksana.dev.rtsoft.ru> <20100511175812.GH30801@buzzloop.caiaq.de> <20100511182347.GA31831@oksana.dev.rtsoft.ru> <20100511222825.GJ30801@buzzloop.caiaq.de> <20100512181546.GA4804@oksana.dev.rtsoft.ru> <20100512183806.GA28658@suse.de> <20100512190814.GA9674@oksana.dev.rtsoft.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 12, 2010 at 09:12:46PM +0200, Kay Sievers wrote: > On Wed, May 12, 2010 at 21:08, Anton Vorontsov wrote: > > On Wed, May 12, 2010 at 11:38:06AM -0700, Greg KH wrote: > >> On Wed, May 12, 2010 at 10:15:46PM +0400, Anton Vorontsov wrote: > >> > We need to create attributes with different modes across devices. > >> > We can do this by modifying attr.mode between device_create_file > >> > invocations, but that is racy in case of globally defined attrs. > >> > > >> > Luckily, there's sysfs_add_file_mode() function that seems to do > >> > exactly what we want, and if we use it, we don't need any locks > >> > to avoid races. Though, it isn't exposed via device-drivers core > >> > API. > >> > >> But you race the creation of the device notifying userspace, and then > >> the file being created, right? > > > > Yep, you've raised that question once, like 3 years ago. :-) > > > > http://lkml.org/lkml/2007/4/11/452 > > http://lkml.org/lkml/2007/4/12/144 > > > > In short: we can't use attr groups since the attributes creation > > is conditional. And we especially don't want to use the attr groups > > for attrs with different modes. But it's not a problem, because... > > Groups have a filter callback for every member, to decide if the > attribute should be created or not. Yeah, that's how we solved that issue a long time ago :) Can you please switch to using attribute groups now, so that userspace doesn't have to handle 'change' events? thanks, greg k-h