From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755825Ab1I2Dnh (ORCPT ); Wed, 28 Sep 2011 23:43:37 -0400 Received: from szxga03-in.huawei.com ([119.145.14.66]:64433 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754478Ab1I2Dng (ORCPT ); Wed, 28 Sep 2011 23:43:36 -0400 Date: Thu, 29 Sep 2011 11:41:35 +0800 From: "canquan.shen" Subject: Re: [PATCH v5] acpi: Fix CPU hot removal problem In-reply-to: <4E83E27E.5090608@linux.intel.com> X-Originating-IP: [10.166.80.130] To: Chen Gong Cc: len.brown@intel.com, Bjorn Helgaas , "shemminger@vyatta.com" , "yakui.zhao@intel.com" , "xiaowei.yang@huawei.com" , hanweidong , linqiangmin@huawei.com, "linux-kernel@vger.kernel.org" , "linux-acpi@vger.kernel.org" , khalid.aziz@hp.com Message-id: <4E83E8EF.30806@huawei.com> MIME-version: 1.0 Content-type: text/plain; charset=UTF-8; format=flowed Content-transfer-encoding: 8BIT User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:7.0) Gecko/20110922 Thunderbird/7.0 X-CFilter-Loop: Reflected References: <4E7D7468.4040506@huawei.com> <4E83E27E.5090608@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2011/9/29 11:14, Chen Gong wrote: > 于 2011/9/24 14:10, canquan.shen 写道: >> We run linux as a guest in Xen environment. When we used the xen tools >> (xm vcpu-set ) to hot add and remove vcpu to and from the guest, we >> encountered the failure on vcpu removal. We found the reason is that it >> did't go to really remove cpu in the cpu removal code path. >> >> This patch adds acpi_bus_hot_remove_device in >> acpi_process_hotplug_notify to >> fix this issue. With this patch, it works fine for us. >> >> Signed-off-by: Canquan Shen >> --- >> drivers/acpi/processor_driver.c | 13 +------------ >> drivers/acpi/scan.c | 4 ++-- >> include/acpi/acpi_bus.h | 1 + >> 3 files changed, 4 insertions(+), 14 deletions(-) >> >> diff --git a/drivers/acpi/processor_driver.c >> b/drivers/acpi/processor_driver.c >> index a4e0f1b..8429688 100644 >> --- a/drivers/acpi/processor_driver.c >> +++ b/drivers/acpi/processor_driver.c >> @@ -665,18 +665,7 @@ static void >> acpi_processor_hotplug_notify(acpi_handle handle, >> case ACPI_NOTIFY_EJECT_REQUEST: >> ACPI_DEBUG_PRINT((ACPI_DB_INFO, >> "received ACPI_NOTIFY_EJECT_REQUEST\n")); >> - >> - if (acpi_bus_get_device(handle, &device)) { >> - printk(KERN_ERR PREFIX >> - "Device don't exist, dropping EJECT\n"); >> - break; >> - } >> - pr = acpi_driver_data(device); >> - if (!pr) { >> - printk(KERN_ERR PREFIX >> - "Driver data is NULL, dropping EJECT\n"); >> - return; >> - } >> + acpi_bus_hot_remove_device(handle); > > As the description in __acpi_os_execute(in acpi_os_hotplug_execute), > /* > * We can't run hotplug code in keventd_wq/kacpid_wq/kacpid_notify_wq > * because the hotplug code may call driver .remove() functions, > * which invoke flush_scheduled_work/acpi_os_wait_events_complete > * to flush these workqueues. > */ > If so, why not using following call: > > acpi_os_hotplug_execute(acpi_bus_hot_remove_device, acpi_device->handle); > > It is ok if using the acpi_os_hotplug_execute. but it is complex and more time for removal cpu because it is add to queue and some time the work will be called. I think that it is clear to call directly acpi_bus_hot_remove_device function in acpi_processor_hotplug_notify. > -- > 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/ > > . >