From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754225AbdE0Ia4 (ORCPT ); Sat, 27 May 2017 04:30:56 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:43597 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754162AbdE0Iay (ORCPT ); Sat, 27 May 2017 04:30:54 -0400 Date: Sat, 27 May 2017 10:30:51 +0200 (CEST) From: Thomas Gleixner To: Jeffy Chen cc: linux-kernel@vger.kernel.org, briannorris@chromium.org, dianders@chromium.org, tfiga@chromium.org Subject: Re: [PATCH v2] genirq: Check irq disabled & masked states in irq_shutdown In-Reply-To: <1495860765-32399-1-git-send-email-jeffy.chen@rock-chips.com> Message-ID: References: <1495860765-32399-1-git-send-email-jeffy.chen@rock-chips.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 Sat, 27 May 2017, Jeffy Chen wrote: > If a irq is already disabled & masked, free_irq may cause a unbalanced > irq shutdown/disable/mask, for example: No, it's not. irq_shutdown/disable/mask are low level access functions which can be invoked at any given time. The only interface which has refcounting is disable/enable_irq(). > devm_request_irq->irq_startup->irq_enable > disable_irq <-- disabled and masked > devm_free_irq->irq_shutdown <-- try to disable it again > > This would confuse some pinctrl drivers which would control clk in > irq_enable/irq_disable, for example pinctrl-rockchip/pinctrl-nomadik. > > This patch add a state check in irq_shutdown to prevent that. Please read Documentation/process/SubmittingPatches and search for "this patch". > diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c > index 686be4b..816da03 100644 > --- a/kernel/irq/chip.c > +++ b/kernel/irq/chip.c > @@ -206,14 +206,20 @@ int irq_startup(struct irq_desc *desc, bool resend) > > void irq_shutdown(struct irq_desc *desc) > { > - irq_state_set_disabled(desc); > desc->depth = 1; > + > + if (unlikely(irqd_irq_disabled(&desc->irq_data) && > + irqd_irq_masked(&desc->irq_data))) > + goto out; This is just wrong. It's perfectly legit to call disable_irq() and then free_irq(). Still free_irq() has to be able to invoke chip->irq_shutdown(). Preventing that will leave some interrupt chips in a half initialized state. The irq core does not guarntee that the unmask/mask enable/disable startup/shutdown callbacks are perfectly balanced. irq_shutdown() is only one place where this can happen. This needs more thought than this 'works for me' hackery. Thanks, tglx