From patchwork Sun May 17 05:19:34 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 6422331 Return-Path: X-Original-To: patchwork-linux-pm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 8D160C0432 for ; Sun, 17 May 2015 05:20:08 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id E762C2052C for ; Sun, 17 May 2015 05:20:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 345162051A for ; Sun, 17 May 2015 05:20:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750879AbbEQFTv (ORCPT ); Sun, 17 May 2015 01:19:51 -0400 Received: from cantor2.suse.de ([195.135.220.15]:45841 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750787AbbEQFTv (ORCPT ); Sun, 17 May 2015 01:19:51 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 20CF7AAC7; Sun, 17 May 2015 05:19:49 +0000 (UTC) Date: Sun, 17 May 2015 15:19:34 +1000 From: NeilBrown To: Thomas Gleixner , Peter Zijlstra , "Rafael J. Wysocki" Cc: linux-kernel@vger.kernel.org, GTA04 owners , linux-pm@vger.kernel.org, Kalle Jokiniemi Subject: [PATCH - RE-RESEND] IRQ: don't suspend nested_thread irqs over system suspend. Message-ID: <20150517151934.2393e8f8@notabene.brown> X-Mailer: Claws Mail 3.10.1-162-g4d0ed6 (GTK+ 2.24.25; x86_64-suse-linux-gnu) MIME-Version: 1.0 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, T_TVD_MIME_EPI, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Nested IRQs can only fire when the parent irq fires. So when the parent is suspended, there is no need to suspend the child irq. Suspending nested irqs can cause a problem is they are suspended or resumed in the wrong order. If an interrupt fires while the parent is active but the child is suspended, then the interrupt will not be acknowledged properly and so an interrupt storm can result. This is particularly likely if the parent is resumed before the child, and the interrupt was raised during suspend. Ensuring correct ordering would be possible, but it is simpler to just never suspend nested interrupts. Signed-off-by: NeilBrown Acked-by: Peter Zijlstra (Intel) --- At Rafael's request I'm resending this. No response last time (except from Rafael), no change in the code. This change will fix a bug so that the work-around introduced by 8b41669ceba0 ("mfd: twl4030: Fix chained irq handling on resume from suspend") can be reverted. This work-around misuses the IRQF_EARLY_RESUME flag, and triggers a warning on resume: [ 56.095825] WARNING: CPU: 0 PID: 3 at ../kernel/irq/manage.c:661 irq_nested_primary_handler+0x18/0x28() (though the line number might have changed). NeilBrown diff --git a/kernel/irq/pm.c b/kernel/irq/pm.c index 5204a6d1b985..d22786a6dbde 100644 --- a/kernel/irq/pm.c +++ b/kernel/irq/pm.c @@ -123,6 +123,8 @@ void suspend_device_irqs(void) unsigned long flags; bool sync; + if (irq_settings_is_nested_thread(desc)) + continue; raw_spin_lock_irqsave(&desc->lock, flags); sync = suspend_device_irq(desc, irq); raw_spin_unlock_irqrestore(&desc->lock, flags); @@ -163,6 +165,8 @@ static void resume_irqs(bool want_early) if (!is_early && want_early) continue; + if (irq_settings_is_nested_thread(desc)) + continue; raw_spin_lock_irqsave(&desc->lock, flags); resume_irq(desc, irq);