Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932188Ab0FIKVL (ORCPT ); Wed, 9 Jun 2010 06:21:11 -0400 Received: from ist.d-labs.de ([213.239.218.44]:42937 "EHLO mx01.d-labs.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754218Ab0FIKVJ (ORCPT ); Wed, 9 Jun 2010 06:21:09 -0400 Date: Wed, 9 Jun 2010 12:20:50 +0200 From: Florian Mickler To: Johannes Berg Cc: pm list , james.bottomley@suse.de, markgross@thegnar.org, mgross@linux.intel.com, "John W. Linville" , "David S. Miller" , Javier Cardona , Jouni Malinen , Rui Paulo , Kalle Valo , linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Thomas Gleixner Subject: Re: [RFC PATCH 1/2] mac80211: make max_network_latency notifier atomic safe Message-ID: <20100609122050.1dd18132@schatten.dmk.lab> In-Reply-To: <1276076287.3727.15.camel@jlt3.sipsolutions.net> References: <1276074915-26879-1-git-send-email-florian@mickler.org> <1276076287.3727.15.camel@jlt3.sipsolutions.net> X-Mailer: Claws Mail 3.7.6 (GTK+ 2.18.9; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1820 Lines: 43 On Wed, 09 Jun 2010 11:38:07 +0200 Johannes Berg wrote: > On Wed, 2010-06-09 at 11:15 +0200, florian@mickler.org wrote: > > In order to have the pm_qos framework be callable from interrupt > > context, all listeners have to also be callable in that context. > > That makes no sense at all. Why add work structs _everywhere_ in the > callees and make the API harder to use and easy to get wrong completely, > instead of just adding a single work struct that will be queued from the > caller and dealing with the locking complexity etc. just once. > > johannes Just to defend this approach, but I'm certainly not married to it (hence RFC): There are only two listeners at the moment. I suspect that most future uses of the framework need to be atomic, as the driver that requests a specific quality of service probably doesn't want to get into races with the provider of that service(listener). So i suspected the network listener to be the special case. The race between service-provider and qos-requester for non-atomic contextes is already there, isn't it? so, locking complexity shouldn't be worse than before. But my first approach to this is seen here: https://lists.linux-foundation.org/pipermail/linux-pm/2010-June/026902.html A third possibility would be to make it dependent on the type of the constraint, if blocking notifiers are allowed or not. But that would sacrifice API consistency (update_request for one constraint is allowed to be called in interrupt context and update_request for another would be not). Cheers, Flo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/