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=-6.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 C58E6C43441 for ; Sun, 11 Nov 2018 23:21:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 879D020869 for ; Sun, 11 Nov 2018 23:21:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="XA39mrdg" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 879D020869 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org 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 S2389751AbeKLJLf (ORCPT ); Mon, 12 Nov 2018 04:11:35 -0500 Received: from mail.kernel.org ([198.145.29.99]:47890 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389441AbeKLIVO (ORCPT ); Mon, 12 Nov 2018 03:21:14 -0500 Received: from localhost (unknown [206.108.79.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 729AD2154B; Sun, 11 Nov 2018 22:31:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541975476; bh=NQ/7Yx61gej25bFU3J4iukZNm8fxgwrW+I6VR9X8GKE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XA39mrdgICPCW4hxDRVdYdtuTuLpdHoQ29uGFlWGx9eTDmNAI0vUE21mZYotbIQkE JCsg6GJtY/2qruHJPZJpl3KpaViuJiCeWc/Lqyi5BOIbP899WWq32bRggkH7QEtmem 6N6MooMVvwZun85GIwEJkNeNch1UrhYT+RsKdAwo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lukas Wunner , Thomas Gleixner , Mathias Duckeck , Akshay Bhat , Casey Fitzpatrick Subject: [PATCH 4.18 260/350] genirq: Fix race on spurious interrupt detection Date: Sun, 11 Nov 2018 14:22:04 -0800 Message-Id: <20181111221718.890768988@linuxfoundation.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181111221707.043394111@linuxfoundation.org> References: <20181111221707.043394111@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lukas Wunner commit 746a923b863a1065ef77324e1e43f19b1a3eab5c upstream. 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 Signed-off-by: Greg Kroah-Hartman --- kernel/irq/manage.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -920,6 +920,9 @@ irq_forced_thread_fn(struct irq_desc *de 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; @@ -936,6 +939,9 @@ static irqreturn_t irq_thread_fn(struct 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; } @@ -1013,8 +1019,6 @@ 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);