From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757173AbbCCTma (ORCPT ); Tue, 3 Mar 2015 14:42:30 -0500 Received: from e39.co.us.ibm.com ([32.97.110.160]:39960 "EHLO e39.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755208AbbCCTm3 (ORCPT ); Tue, 3 Mar 2015 14:42:29 -0500 Date: Tue, 3 Mar 2015 11:42:23 -0800 From: "Paul E. McKenney" To: Boris Ostrovsky Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, x86@kernel.org, Konrad Rzeszutek Wilk , David Vrabel , xen-devel@lists.xenproject.org Subject: Re: [PATCH tip/core/rcu 02/20] x86: Use common outgoing-CPU-notification code Message-ID: <20150303194223.GR15405@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20150303174144.GA13139@linux.vnet.ibm.com> <1425404595-17816-1-git-send-email-paulmck@linux.vnet.ibm.com> <1425404595-17816-2-git-send-email-paulmck@linux.vnet.ibm.com> <54F608C4.40405@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <54F608C4.40405@oracle.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15030319-0033-0000-0000-000003D9F2FA Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 03, 2015 at 02:17:24PM -0500, Boris Ostrovsky wrote: > On 03/03/2015 12:42 PM, Paul E. McKenney wrote: > > } > >@@ -511,7 +508,8 @@ static void xen_cpu_die(unsigned int cpu) > > schedule_timeout(HZ/10); > > } > >- cpu_die_common(cpu); > >+ (void)cpu_wait_death(cpu, 5); > >+ /* FIXME: Are the below calls really safe in case of timeout? */ > > > Not for HVM guests (PV guests will only reach this point after > target cpu has been marked as down by the hypervisor). > > We need at least to have a message similar to what native_cpu_die() > prints on cpu_wait_death() failure. And I think we should not call > the two routines below (three, actually --- there is also > xen_teardown_timer() below, which is not part of the diff). > > -boris > > > > xen_smp_intr_free(cpu); > > xen_uninit_lock_cpu(cpu); So something like this, then? if (cpu_wait_death(cpu, 5)) { xen_smp_intr_free(cpu); xen_uninit_lock_cpu(cpu); xen_teardown_timer(cpu); } Easy change for me to make if so! Or do I need some other check for HVM-vs.-PV guests, and, if so, what would that check be? And also if so, is it OK to online a PV guest's CPU that timed out during its previous offline? Thanx, Paul