From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763802AbXGZJA1 (ORCPT ); Thu, 26 Jul 2007 05:00:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756966AbXGZJAT (ORCPT ); Thu, 26 Jul 2007 05:00:19 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:60480 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756417AbXGZJAS (ORCPT ); Thu, 26 Jul 2007 05:00:18 -0400 Date: Thu, 26 Jul 2007 11:00:12 +0200 From: Ingo Molnar To: Andrew Morton Cc: linux-kernel@vger.kernel.org Subject: [patch] sched: make cpu_clock() not use the rq clock Message-ID: <20070726090012.GA5287@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.14 (2007-02-12) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.0.3 -1.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Subject: sched: make cpu_clock() not use the rq clock From: Ingo Molnar it is enough to disable interrupts to get the precise rq-clock of the local CPU. this also solves an NMI watchdog regression: the NMI watchdog calls touch_softlockup_watchdog(), which might deadlock on rq->lock if the NMI hits an rq-locked critical section. Signed-off-by: Ingo Molnar --- kernel/sched.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) Index: linux-rt-rebase.q/kernel/sched.c =================================================================== --- linux-rt-rebase.q.orig/kernel/sched.c +++ linux-rt-rebase.q/kernel/sched.c @@ -446,13 +446,12 @@ static inline unsigned long long rq_cloc */ unsigned long long cpu_clock(int cpu) { - struct rq *rq = cpu_rq(cpu); unsigned long long now; unsigned long flags; - spin_lock_irqsave(&rq->lock, flags); - now = rq_clock(rq); - spin_unlock_irqrestore(&rq->lock, flags); + local_irq_save(flags); + now = rq_clock(cpu_rq(cpu)); + local_irq_restore(flags); return now; }