From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753741AbdF2VpZ (ORCPT ); Thu, 29 Jun 2017 17:45:25 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:59321 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752728AbdF2VpT (ORCPT ); Thu, 29 Jun 2017 17:45:19 -0400 Message-Id: <20170629214344.117028181@linutronix.de> User-Agent: quilt/0.63-1 Date: Thu, 29 Jun 2017 23:33:38 +0200 From: Thomas Gleixner To: LKML Cc: Marc Zyngier , Linus Walleij , Brian Norris , Heiko Stuebner , linux-rockchip@lists.infradead.org, Julia Cartwright , linux-gpio@vger.kernel.org, John Keeping , Doug Anderson Subject: [patch 4/5] genirq: Move irq resource handling out of spinlocked region References: <20170629213334.375848050@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Disposition: inline; filename=genirq--Move-irq-resource-handling-out-of-spinlocked-region.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Aside of being conceptually wrong, there is also an actual (hard to trigger and mostly theoretical) problem. CPU0 CPU1 free_irq(X) interrupt X spin_lock(desc->lock) wake irq thread() spin_unlock(desc->lock) spin_lock(desc->lock) remove action() shutdown_irq() release_resources() thread_handler() spin_unlock(desc->lock) access released resources. synchronize_irq() Move the release resources invocation after synchronize_irq() so it's guaranteed that the threaded handler has finished. Move the resource request call out of the desc->lock held region as well, so the invocation context is the same for both request and release. This solves the problems with those functions on RT as well. Signed-off-by: Thomas Gleixner --- kernel/irq/manage.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -1168,6 +1168,14 @@ static int new->flags &= ~IRQF_ONESHOT; mutex_lock(&desc->request_mutex); + if (!desc->action) { + ret = irq_request_resources(desc); + if (ret) { + pr_err("Failed to request resources for %s (irq %d) on irqchip %s\n", + new->name, irq, desc->irq_data.chip->name); + goto out_mutex; + } + } chip_bus_lock(desc); @@ -1271,13 +1279,6 @@ static int } if (!shared) { - ret = irq_request_resources(desc); - if (ret) { - pr_err("Failed to request resources for %s (irq %d) on irqchip %s\n", - new->name, irq, desc->irq_data.chip->name); - goto out_unlock; - } - init_waitqueue_head(&desc->wait_for_threads); /* Setup the type (level, edge polarity) if configured: */ @@ -1386,6 +1387,10 @@ static int chip_bus_sync_unlock(desc); + if (!desc->action) + irq_release_resources(desc); + +out_mutex: mutex_unlock(&desc->request_mutex); out_thread: @@ -1484,7 +1489,6 @@ static struct irqaction *__free_irq(unsi if (!desc->action) { irq_settings_clr_disable_unlazy(desc); irq_shutdown(desc); - irq_release_resources(desc); irq_remove_timings(desc); } @@ -1527,6 +1531,9 @@ static struct irqaction *__free_irq(unsi } } + if (!desc->action) + irq_release_resources(desc); + mutex_unlock(&desc->request_mutex); irq_chip_pm_put(&desc->irq_data);