From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757271Ab0ELTbA (ORCPT ); Wed, 12 May 2010 15:31:00 -0400 Received: from mail-wy0-f174.google.com ([74.125.82.174]:39550 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757111Ab0ELTa5 (ORCPT ); Wed, 12 May 2010 15:30:57 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=xCKykjApqHXI+XnKD9b9TETTQO1aP0f9sDN4VRPAXO4dE5p9u8kUjZ5sC2Mr6EQKai MoIvMV8FiqYe2RWxOptlLZtfLE9RAujUfLrbcde+5hTNwyCeORtG5ksO408wY++tc+bF 4PNK+mUMCAThE5Mx2AstPFcPlqWsMtLHBfu8A= Date: Wed, 12 May 2010 23:30:50 +0400 From: Anton Vorontsov To: Kay Sievers Cc: Greg KH , 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: <20100512193050.GA14221@oksana.dev.rtsoft.ru> 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=utf-8 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. Thanks Kay. It seems the callback was added just a few months after the discussion above. ;-) And this commit looks especially cool: commit 0f4238958d28044b335644b69df6071cdb04b5ce Author: James Bottomley Date: Thu Mar 20 20:47:52 2008 -0500 [SCSI] sysfs: make group is_valid return a mode_t Daniel, I think that today we can just use the attribute group mechanism, it has all needed. Do you want me to prepare a patch to convert existing attributes, or do you to try it yourself? Just asking to not duplicate efforts. -- Anton Vorontsov email: cbouatmailru@gmail.com irc://irc.freenode.net/bd2