From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932582AbaICMke (ORCPT ); Wed, 3 Sep 2014 08:40:34 -0400 Received: from fw-tnat.austin.arm.com ([217.140.110.23]:19264 "EHLO collaborate-mta1.arm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932220AbaICMkd (ORCPT ); Wed, 3 Sep 2014 08:40:33 -0400 Message-ID: <54070C3C.1050201@arm.com> Date: Wed, 03 Sep 2014 13:40:28 +0100 From: Marc Zyngier User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130330 Thunderbird/17.0.5 MIME-Version: 1.0 To: Jason Cooper CC: Thomas Gleixner , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-omap@vger.kernel.org" , "linux@arm.linux.org.uk" , "shawn.guo@freescale.com" , "kernel@pengutronix.de" , "tony@atomide.com" , Catalin Marinas , Will Deacon , "jonas@southpole.se" , "shc_work@mail.ru" , "baohua@kernel.org" , "maxime.ripard@free-electrons.com" , "khilman@linaro.org" , "sboyd@codeaurora.org" , Lorenzo Pieralisi , "larry.bassel@linaro.org" , Mark Rutland , Sudeep Holla , "stefan.kristiansson@saunalahti.fi" , "vkale@apm.com" , "schwidefsky@de.ibm.com" Subject: Re: [PATCH v2 00/26] genirq: fix use of irq_find_mapping outside of legal RCU context References: <1409047421-27649-1-git-send-email-marc.zyngier@arm.com> <87y4uap98n.fsf@approximate.cambridge.arm.com> <20140903120406.GK30467@titan.lakedaemon.net> <540707B3.4050305@arm.com> <20140903123729.GM30467@titan.lakedaemon.net> In-Reply-To: <20140903123729.GM30467@titan.lakedaemon.net> X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/09/14 13:37, Jason Cooper wrote: > On Wed, Sep 03, 2014 at 02:25:09PM +0200, Thomas Gleixner wrote: >> On Wed, 3 Sep 2014, Marc Zyngier wrote: >>> [Dropping linux@openrisc.net from the CC list] >>> >>> On 03/09/14 13:09, Thomas Gleixner wrote: >>>> On Wed, 3 Sep 2014, Jason Cooper wrote: >>>> >>>>> On Wed, Aug 27, 2014 at 10:33:44AM +0100, Marc Zyngier wrote: >>>>>> Hi Thomas, >>>>>> >>>>>> On Tue, Aug 26 2014 at 10:34:51 pm BST, Thomas Gleixner wrote: >>>>>>> On Tue, 26 Aug 2014, Marc Zyngier wrote: >>>>>>> >>>>>>>> A number of irqchip drivers are directly calling irq_find_mapping, >>>>>>>> which may use a rcu_read_lock call when walking the radix tree. >>>>>>>> >>>>>>>> Turns out that if you hit that point with CONFIG_PROVE_RCU enabled, >>>>>>>> the kernel will shout at you, as using RCU in this context may be >>>>>>>> illegal (specially if coming from the idle state, where RCU would be >>>>>>>> in a quiescent state). >>>>>>>> >>>>>>>> A possible fix would be to wrap calls to irq_find_mapping into a >>>>>>>> RCU_NONIDLE macro, but that really looks ugly. >>>>>>>> >>>>>>>> This patch series introduce another generic IRQ entry point >>>>>>>> (handle_domain_irq), which has the exact same behaviour as handle_IRQ >>>>>>>> (as defined on arm, arm64 and openrisc), except that it also takes a >>>>>>>> irq_domain pointer. This allows the logical IRQ lookup to be done >>>>>>>> inside the irq_{enter,exit} section, which contains a >>>>>>>> rcu_irq_{enter,exit}, making it safe. >>>>>>> >>>>>>> Looks good. Should this be routed to the genirq tree? >>>>>> >>>>>> I'm happy for you to take this series, provided the architecture >>>>>> maintainers agree on it (I'm still to hear from the openrisc guys, and >>>>>> their mailing-list seems to positively hate my guts). >>>>> >>>>> I think everyone's had a chance to look over it by now. Thomas, shall I >>>>> take the series? >>>> >>>> Yes please. >>> >>> Do you want a pull request? Or are you picking up the patches from the ML? >> >> Did you pick up the Acked/Reviewed/Ignored-by tags? > > Marc, unless you've already done it, I'll pull from the ml, since I need > to apply the Acked-bys and tweak the subject lines. If you're going to repaint the subject lines, then I'll leave you to it! ;-) M. -- Jazz is not dead. It just smells funny...