From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Cooper Subject: Re: [PATCH v2 00/26] genirq: fix use of irq_find_mapping outside of legal RCU context Date: Wed, 3 Sep 2014 08:04:06 -0400 Message-ID: <20140903120406.GK30467@titan.lakedaemon.net> References: <1409047421-27649-1-git-send-email-marc.zyngier@arm.com> <87y4uap98n.fsf@approximate.cambridge.arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mho-02-ewr.mailhop.org ([204.13.248.72]:40736 "EHLO mho-02-ewr.mailhop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755478AbaICMFA (ORCPT ); Wed, 3 Sep 2014 08:05:00 -0400 Content-Disposition: inline In-Reply-To: <87y4uap98n.fsf@approximate.cambridge.arm.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Marc Zyngier Cc: Thomas Gleixner , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-omap@vger.kernel.org" , "linux@openrisc.net" , "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 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? thx, Jason.