From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754508AbdJSOIu (ORCPT ); Thu, 19 Oct 2017 10:08:50 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:33583 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754374AbdJSOIr (ORCPT ); Thu, 19 Oct 2017 10:08:47 -0400 Date: Thu, 19 Oct 2017 16:08:39 +0200 (CEST) From: Thomas Gleixner To: Paul Burton cc: Ralf Baechle , dianders@chromium.org, James Hogan , Brian Norris , Jason Cooper , jeffy.chen@rock-chips.com, Marc Zyngier , linux-kernel@vger.kernel.org, linux-mips@linux-mips.org, tfiga@chromium.org Subject: Re: [RFC PATCH v1 2/9] genirq: Support shared per_cpu_devid interrupts In-Reply-To: Message-ID: References: <1682867.tATABVWsV9@np-p-burton> <20170907232542.20589-1-paul.burton@imgtec.com> <20170907232542.20589-3-paul.burton@imgtec.com> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 26 Sep 2017, Thomas Gleixner wrote: > On Mon, 25 Sep 2017, Thomas Gleixner wrote: > > > On Thu, 7 Sep 2017, Paul Burton wrote: > > > Up until now per_cpu_devid interrupts have not supported sharing. On > > > MIPS we have some percpu interrupts which are shared in many systems - > > > a single CPU interrupt line may be used to indicate a timer interrupt, > > > performance counter interrupt or fast debug channel interrupt. We have > > > up until now supported this with a series of hacks, wherein drivers call > > > each other's interrupt handlers & our MIPS GIC irqchip driver includes a > > > hack which configures the interrupt(s) for all CPUs. In order to allow > > > this mess to be cleaned up, this patch introduces support for shared > > > per_cpu_devid interrupts. > > > > > > The major portion of this is supporting per_cpu_devid interrupts in > > > __handle_irq_event_percpu() and then making use of this, via > > > handle_irq_event_percpu(), from handler_percpu_devif_irq() to invoke the > > > handler for all actions associated with the shared interrupt. This does > > > have a few side effects worth noting: > > > > > > - per_cpu_devid interrupts will now add to the entropy pool via > > > add_interrupt_randomness(), where they previously did not. > > > > > > - per_cpu_devid interrupts will record timings when IRQS_TIMINGS is > > > set, via record_irq_time(), where they previously did not. > > > > > > - per_cpu_devid interrupts will handle an IRQ_WAKE_THREAD return from > > > their handlers to wake a thread, where they previously did not. > > > > That's broken because it lacks the magic synchronization which is described > > in the comment in __irq_wake_thread(). > > Aside of that to make that work at all would require per cpu threads and > not a single systemwide thread. also request_threaded_irq() will yell at you if you call it for a percpu interrupt. Care to rewrite the changelog and make that conditional: irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc, unsigned int *flags) { + bool percpu = irq_settings_is_per_cpu_devid(desc); irqreturn_t retval = IRQ_NONE; unsigned int irq = desc->irq_data.irq; struct irqaction *action; @@ -142,9 +143,15 @@ irqreturn_t __handle_irq_event_percpu(st for_each_action_of_desc(desc, action) { irqreturn_t res; + void *dev_id; + + if (!percpu)) + dev_id = action->dev_id; + else + dev_id = raw_cpu_ptr(action->percpu_dev_id); Thanks, tglx