From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752930AbbGERNJ (ORCPT ); Sun, 5 Jul 2015 13:13:09 -0400 Received: from www.linutronix.de ([62.245.132.108]:52094 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752087AbbGERMj (ORCPT ); Sun, 5 Jul 2015 13:12:39 -0400 Message-Id: <20150705171102.331320612@linutronix.de> User-Agent: quilt/0.63-1 Date: Sun, 05 Jul 2015 17:12:35 -0000 From: Thomas Gleixner To: LKML Cc: Ingo Molnar , Peter Zijlstra , Peter Anvin , xiao jin , Joerg Roedel , Borislav Petkov , Yanmin Zhang Subject: [patch 4/4] x86/irq: Retrieve irq data after locking irq_desc References: <20150705170530.849428850@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Disposition: inline; filename=x86-irq-protect-fixup-irqs.patch X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001,URIBL_BLOCKED=0.001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org irq_data is protected by irq_desc->lock, so retrieving the irq chip from irq_data outside the lock is racy vs. an concurrent update. Move it into the lock held region. While at it add a comment why the vector walk does not require vector_lock. Signed-off-by: Thomas Gleixner --- arch/x86/kernel/irq.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) Index: tip/arch/x86/kernel/irq.c =================================================================== --- tip.orig/arch/x86/kernel/irq.c +++ tip/arch/x86/kernel/irq.c @@ -497,6 +497,11 @@ void fixup_irqs(void) */ mdelay(1); + /* + * We can walk the vector array of this cpu without holding + * vector_lock because the cpu is already marked !online, so + * nothing else will touch it. + */ for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) { unsigned int irr; @@ -508,9 +513,9 @@ void fixup_irqs(void) irq = __this_cpu_read(vector_irq[vector]); desc = irq_to_desc(irq); + raw_spin_lock(&desc->lock); data = irq_desc_get_irq_data(desc); chip = irq_data_get_irq_chip(data); - raw_spin_lock(&desc->lock); if (chip->irq_retrigger) { chip->irq_retrigger(data); __this_cpu_write(vector_irq[vector], VECTOR_RETRIGGERED);