From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756712AbbFPTZa (ORCPT ); Tue, 16 Jun 2015 15:25:30 -0400 Received: from www.linutronix.de ([62.245.132.108]:46322 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754725AbbFPTZW (ORCPT ); Tue, 16 Jun 2015 15:25:22 -0400 Date: Tue, 16 Jun 2015 21:25:20 +0200 (CEST) From: Thomas Gleixner To: Vikas Shivappa cc: Vikas Shivappa , linux-kernel@vger.kernel.org, x86@kernel.org, hpa@zytor.com, mingo@kernel.org, peterz@infradead.org, matt.fleming@intel.com, will.auld@intel.com, linux-rdt@eclists.intel.com Subject: Re: [PATCH 09/10] x86/intel_rdt: Hot cpu support for Cache Allocation In-Reply-To: Message-ID: References: <1434133037-25189-1-git-send-email-vikas.shivappa@linux.intel.com> <1434133037-25189-10-git-send-email-vikas.shivappa@linux.intel.com> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII 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 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 16 Jun 2015, Vikas Shivappa wrote: > On Tue, 16 Jun 2015, Thomas Gleixner wrote: > > > On Fri, 12 Jun 2015, Vikas Shivappa wrote: > > > +static inline void intel_rdt_cpu_start(int cpu) > > > +{ > > > + struct intel_pqr_state *state = &per_cpu(pqr_state, cpu); > > > + > > > + state->closid = 0; > > > + mutex_lock(&rdt_group_mutex); > > > > This is called from CPU_STARTING, which runs on the starting cpu with > > interrupts disabled. Clearly never tested with any of the mandatory > > debug configs enabled. > > But this can race with cbm_update_all calling on_each_cpu_mask ? or in other > words the lock helps on_each_cpu_mask not race with hot cpu code updating the > rdt_cpumask since the on_each_cpu_mask is also called with the lock always. > > Its tested on the 0 day build which should include the debug config. Will add > a tested tag. And that tag gives you special permission to take a mutex in irq disabled context on a cpu which cannot schedule, right? Thanks, tglx