From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A58C9ECDE43 for ; Fri, 19 Oct 2018 15:34:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 74DA92083E for ; Fri, 19 Oct 2018 15:34:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 74DA92083E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zytor.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727528AbeJSXkg (ORCPT ); Fri, 19 Oct 2018 19:40:36 -0400 Received: from terminus.zytor.com ([198.137.202.136]:39577 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726465AbeJSXkg (ORCPT ); Fri, 19 Oct 2018 19:40:36 -0400 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id w9JFXo0C1288783 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Fri, 19 Oct 2018 08:33:50 -0700 Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id w9JFXoI51288780; Fri, 19 Oct 2018 08:33:50 -0700 Date: Fri, 19 Oct 2018 08:33:50 -0700 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Lukas Wunner Message-ID: Cc: mingo@kernel.org, casey.fitzpatrick@timesys.com, lukas@wunner.de, akshay.bhat@timesys.com, hpa@zytor.com, linux-kernel@vger.kernel.org, m.duckeck@kunbus.de, tglx@linutronix.de Reply-To: casey.fitzpatrick@timesys.com, lukas@wunner.de, mingo@kernel.org, tglx@linutronix.de, m.duckeck@kunbus.de, hpa@zytor.com, akshay.bhat@timesys.com, linux-kernel@vger.kernel.org In-Reply-To: <1dfd8bbd16163940648045495e3e9698e63b50ad.1539867047.git.lukas@wunner.de> References: <1dfd8bbd16163940648045495e3e9698e63b50ad.1539867047.git.lukas@wunner.de> To: linux-tip-commits@vger.kernel.org Subject: [tip:irq/core] genirq: Fix race on spurious interrupt detection Git-Commit-ID: 746a923b863a1065ef77324e1e43f19b1a3eab5c X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 746a923b863a1065ef77324e1e43f19b1a3eab5c Gitweb: https://git.kernel.org/tip/746a923b863a1065ef77324e1e43f19b1a3eab5c Author: Lukas Wunner AuthorDate: Thu, 18 Oct 2018 15:15:05 +0200 Committer: Thomas Gleixner CommitDate: Fri, 19 Oct 2018 17:31:00 +0200 genirq: Fix race on spurious interrupt detection Commit 1e77d0a1ed74 ("genirq: Sanitize spurious interrupt detection of threaded irqs") made detection of spurious interrupts work for threaded handlers by: a) incrementing a counter every time the thread returns IRQ_HANDLED, and b) checking whether that counter has increased every time the thread is woken. However for oneshot interrupts, the commit unmasks the interrupt before incrementing the counter. If another interrupt occurs right after unmasking but before the counter is incremented, that interrupt is incorrectly considered spurious: time | irq_thread() | irq_thread_fn() | action->thread_fn() | irq_finalize_oneshot() | unmask_threaded_irq() /* interrupt is unmasked */ | | /* interrupt fires, incorrectly deemed spurious */ | | atomic_inc(&desc->threads_handled); /* counter is incremented */ v This is observed with a hi3110 CAN controller receiving data at high volume (from a separate machine sending with "cangen -g 0 -i -x"): The controller signals a huge number of interrupts (hundreds of millions per day) and every second there are about a dozen which are deemed spurious. In theory with high CPU load and the presence of higher priority tasks, the number of incorrectly detected spurious interrupts might increase beyond the 99,900 threshold and cause disablement of the interrupt. In practice it just increments the spurious interrupt count. But that can cause people to waste time investigating it over and over. Fix it by moving the accounting before the invocation of irq_finalize_oneshot(). [ tglx: Folded change log update ] Fixes: 1e77d0a1ed74 ("genirq: Sanitize spurious interrupt detection of threaded irqs") Signed-off-by: Lukas Wunner Signed-off-by: Thomas Gleixner Cc: Mathias Duckeck Cc: Akshay Bhat Cc: Casey Fitzpatrick Cc: stable@vger.kernel.org # v3.16+ Link: https://lkml.kernel.org/r/1dfd8bbd16163940648045495e3e9698e63b50ad.1539867047.git.lukas@wunner.de --- kernel/irq/manage.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index fb86146037a7..9dbdccab3b6a 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -927,6 +927,9 @@ irq_forced_thread_fn(struct irq_desc *desc, struct irqaction *action) local_bh_disable(); ret = action->thread_fn(action->irq, action->dev_id); + if (ret == IRQ_HANDLED) + atomic_inc(&desc->threads_handled); + irq_finalize_oneshot(desc, action); local_bh_enable(); return ret; @@ -943,6 +946,9 @@ static irqreturn_t irq_thread_fn(struct irq_desc *desc, irqreturn_t ret; ret = action->thread_fn(action->irq, action->dev_id); + if (ret == IRQ_HANDLED) + atomic_inc(&desc->threads_handled); + irq_finalize_oneshot(desc, action); return ret; } @@ -1020,8 +1026,6 @@ static int irq_thread(void *data) irq_thread_check_affinity(desc, action); action_ret = handler_fn(desc, action); - if (action_ret == IRQ_HANDLED) - atomic_inc(&desc->threads_handled); if (action_ret == IRQ_WAKE_THREAD) irq_wake_secondary(desc, action);