From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S944732AbdEZTti (ORCPT ); Fri, 26 May 2017 15:49:38 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:42560 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933961AbdEZTtf (ORCPT ); Fri, 26 May 2017 15:49:35 -0400 Date: Fri, 26 May 2017 21:49:29 +0200 (CEST) From: Thomas Gleixner To: Haris Okanovic cc: Anna-Maria Gleixner , Sebastian Andrzej Siewior , linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org, julia.cartwright@ni.com, gratian.crisan@ni.com Subject: Re: [PATCH] Revert "timers: Don't wake ktimersoftd on every tick" In-Reply-To: Message-ID: References: <20170203165151.qbpjothhaqctuzx5@linutronix.de> <20170203182112.18053-1-haris.okanovic@ni.com> <20170210170207.3kzfqyfa4ueh7mih@linutronix.de> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 26 May 2017, Haris Okanovic wrote: > Anna-Maria, > > Look-ahead is implemented by tick_find_expired() and expiry by __run_timers(), > both of which hold timer_base::lock (raw spin lock) while running. Those two > routines shouldn't be able to run simultaneously on the same timer_base. Are > you sure the race isn't in another code path? It happens when softirq runs and drops the spinlock to call the timer function. And from there stuff goes down the drain. Anna-Maria will send you the test case on monday. Thanks, tglx