Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756289Ab2FOBxj (ORCPT ); Thu, 14 Jun 2012 21:53:39 -0400 Received: from mail-pz0-f46.google.com ([209.85.210.46]:40414 "EHLO mail-pz0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755537Ab2FOBxi (ORCPT ); Thu, 14 Jun 2012 21:53:38 -0400 Date: Fri, 15 Jun 2012 10:53:31 +0900 From: Tejun Heo To: Peter Zijlstra Cc: Thomas Gleixner , "Paul E. McKenney" , LKML , Ingo Molnar , "Srivatsa S. Bhat" , Rusty Russell Subject: Re: [RFC patch 2/5] smpboot: Provide infrastructure for percpu hotplug threads Message-ID: <20120615015331.GC12624@mtj.dyndns.org> References: <20120613102823.373180763@linutronix.de> <20120613105815.206105518@linutronix.de> <20120613183301.GE2427@linux.vnet.ibm.com> <1339661331.2559.5.camel@twins> <1339661848.2559.7.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1339661848.2559.7.camel@twins> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1327 Lines: 37 On Thu, Jun 14, 2012 at 10:17:28AM +0200, Peter Zijlstra wrote: > On Thu, 2012-06-14 at 10:08 +0200, Peter Zijlstra wrote: > > On Wed, 2012-06-13 at 20:56 +0200, Thomas Gleixner wrote: > > > If it's just a spurious wakeup then it goes back to sleep right away > > > as nothing cleared the park bit. > > > > Your spurious wakeup will have destroyed the binding though. So you need > > to be careful. > > We should probably do something like the below.. > > TJ does this wreck workqueues? Its somewhat 'creative' in that regard > and really wants fixing. > > --- > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -5018,6 +5018,8 @@ void do_set_cpus_allowed(struct task_str > > cpumask_copy(&p->cpus_allowed, new_mask); > p->nr_cpus_allowed = cpumask_weight(new_mask); > + if (p->nr_cpus_allowed != 1) > + p->flags &= ~PF_THREAD_BOUND; The only reason wq workers use PF_THREAD_BOUND is to prevent userland from mucking with cpus_allowed, so the above wouldn't break anything in itself although userland would be able to wreck it afterwards. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/