From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752708AbbCEVUt (ORCPT ); Thu, 5 Mar 2015 16:20:49 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:46578 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751693AbbCEVUs (ORCPT ); Thu, 5 Mar 2015 16:20:48 -0500 Message-ID: <54F8C807.5070103@oracle.com> Date: Thu, 05 Mar 2015 16:17:59 -0500 From: Boris Ostrovsky User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: paulmck@linux.vnet.ibm.com 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 References: <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> <20150303194223.GR15405@linux.vnet.ibm.com> <54F615D3.2040802@oracle.com> <20150303212647.GZ15405@linux.vnet.ibm.com> <54F6307A.8040003@oracle.com> <20150303223151.GC15405@linux.vnet.ibm.com> <20150304144336.GA8225@linux.vnet.ibm.com> <54F71CCF.9050509@oracle.com> <20150304152515.GL15405@linux.vnet.ibm.com> In-Reply-To: <20150304152515.GL15405@linux.vnet.ibm.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: acsinet22.oracle.com [141.146.126.238] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/04/2015 10:25 AM, Paul E. McKenney wrote: > On Wed, Mar 04, 2015 at 09:55:11AM -0500, Boris Ostrovsky wrote: >> The simple solution is to stop calling native_cpu_die() above but >> I'd like to use common code in native_cpu_die(). I'll see if I can >> carve it out without too much damage to x86. > > Very good, thank you! I look forward to seeing your patch. How about something like this, on top of your original 02/20 patch (this is copy-paste but hopefully it can be applied): arch/x86/include/asm/smp.h | 1 + arch/x86/kernel/smpboot.c | 12 +++++++++++- arch/x86/xen/smp.c | 34 ++++++++++++++++++++-------------- 3 files changed, 32 insertions(+), 15 deletions(-) diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h index 8cd27e0..a5cb4f6 100644 --- a/arch/x86/include/asm/smp.h +++ b/arch/x86/include/asm/smp.h @@ -155,6 +155,7 @@ void native_smp_prepare_cpus(unsigned int max_cpus); void native_smp_cpus_done(unsigned int max_cpus); int native_cpu_up(unsigned int cpunum, struct task_struct *tidle); int native_cpu_disable(void); +int common_cpu_die(unsigned int cpu); void native_cpu_die(unsigned int cpu); void native_play_dead(void); void play_dead_common(void); diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index ff24fbd..c8fa349 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1345,8 +1345,10 @@ int native_cpu_disable(void) return 0; } -void native_cpu_die(unsigned int cpu) +int common_cpu_die(unsigned int cpu) { + int ret = 0; + /* We don't do anything here: idle task is faking death itself. */ /* They ack this in play_dead() by setting CPU_DEAD */ @@ -1355,7 +1357,15 @@ void native_cpu_die(unsigned int cpu) pr_info("CPU %u is now offline\n", cpu); } else { pr_err("CPU %u didn't die...\n", cpu); + ret = -1; } + + return ret; +} + +void native_cpu_die(unsigned int cpu) +{ + common_cpu_die(cpu); } void play_dead_common(void) diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c index e2c7389..1c5e760 100644 --- a/arch/x86/xen/smp.c +++ b/arch/x86/xen/smp.c @@ -455,7 +455,10 @@ static int xen_cpu_up(unsigned int cpu, struct task_struct *idle) xen_setup_timer(cpu); xen_init_lock_cpu(cpu); - /* Xen outgoing CPUs need help cleaning up, so -EBUSY is an error. */ + /* + * PV VCPUs are always successfully taken down (see 'while' loop + * in xen_cpu_die()), so -EBUSY is an error. + */ rc = cpu_check_up_prepare(cpu); if (rc) return rc; @@ -508,12 +511,11 @@ static void xen_cpu_die(unsigned int cpu) schedule_timeout(HZ/10); } - (void)cpu_wait_death(cpu, 5); - /* FIXME: Are the below calls really safe in case of timeout? */ - - xen_smp_intr_free(cpu); - xen_uninit_lock_cpu(cpu); - xen_teardown_timer(cpu); + if (common_cpu_die(cpu) == 0) { + xen_smp_intr_free(cpu); + xen_uninit_lock_cpu(cpu); + xen_teardown_timer(cpu); + } } static void xen_play_dead(void) /* used only with HOTPLUG_CPU */ @@ -745,6 +747,16 @@ static void __init xen_hvm_smp_prepare_cpus(unsigned int max_cpus) static int xen_hvm_cpu_up(unsigned int cpu, struct task_struct *tidle) { int rc; + + /* + * This can happen if CPU was offlined earlier and + * offlining timed out in common_cpu_die(). + */ + if (cpu_report_state(cpu) == CPU_DEAD_FROZEN) { + xen_smp_intr_free(cpu); + xen_uninit_lock_cpu(cpu); + } + /* * xen_smp_intr_init() needs to run before native_cpu_up() * so that IPI vectors are set up on the booting CPU before @@ -766,12 +778,6 @@ static int xen_hvm_cpu_up(unsigned int cpu, struct task_struct *tidle) return rc; } -static void xen_hvm_cpu_die(unsigned int cpu) -{ - xen_cpu_die(cpu); - native_cpu_die(cpu); -} - void __init xen_hvm_smp_init(void) { if (!xen_have_vector_callback) @@ -779,7 +785,7 @@ void __init xen_hvm_smp_init(void) smp_ops.smp_prepare_cpus = xen_hvm_smp_prepare_cpus; smp_ops.smp_send_reschedule = xen_smp_send_reschedule; smp_ops.cpu_up = xen_hvm_cpu_up; - smp_ops.cpu_die = xen_hvm_cpu_die; + smp_ops.cpu_die = xen_cpu_die; smp_ops.send_call_func_ipi = xen_smp_send_call_function_ipi; smp_ops.send_call_func_single_ipi = xen_smp_send_call_function_single_ipi; smp_ops.smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu; -- 1.7.7.6