From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262838AbTLUMk7 (ORCPT ); Sun, 21 Dec 2003 07:40:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262882AbTLUMk7 (ORCPT ); Sun, 21 Dec 2003 07:40:59 -0500 Received: from dbl.q-ag.de ([80.146.160.66]:12770 "EHLO dbl.q-ag.de") by vger.kernel.org with ESMTP id S262838AbTLUMk5 (ORCPT ); Sun, 21 Dec 2003 07:40:57 -0500 Message-ID: <3FE594D0.8000807@colorfullife.com> Date: Sun, 21 Dec 2003 13:40:48 +0100 From: Manfred Spraul User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.4) Gecko/20030624 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Jamie Lokier CC: lse-tech@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [RFC,PATCH] use rcu for fasync_lock References: <3FE492EF.2090202@colorfullife.com> <20031221113640.GF3438@mail.shareable.org> In-Reply-To: <20031221113640.GF3438@mail.shareable.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Jamie Lokier wrote: >Manfred Spraul wrote: > > >>What about switching to rcu? >> >> > >What about killing fasync_helper altogether and using the method that >epoll uses to register "listeners" which send a signal when the poll >state of a device changes? > I think it would be a step in the wrong direction: poll should go away from a simple wake-up to an interface that transfers the band info (POLL_IN, POLL_OUT, etc). Right now at least two passes over the f_poll functions are necessary, because the info which event actually triggered is lost. kill_fasync transfers the band info, thus I don't want to remove it. > >That would trim off code all over the place, make the fast paths a >little bit faster (in the case that there aren't any listeners), and >most importantly make SIGIO reliable for every kind of file descriptor, >instead of the pot luck you get now. > >Just an idea :) > It's a good idea, but requires lots of changes - perhaps it will be necessary to change the pollwait and f_poll prototypes. -- Manfred