Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757514Ab2JDUxn (ORCPT ); Thu, 4 Oct 2012 16:53:43 -0400 Received: from mail-oa0-f46.google.com ([209.85.219.46]:35784 "EHLO mail-oa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756185Ab2JDUxl (ORCPT ); Thu, 4 Oct 2012 16:53:41 -0400 MIME-Version: 1.0 In-Reply-To: <506C0C53.60205@jp.fujitsu.com> References: <506C0AE8.40702@jp.fujitsu.com> <506C0C53.60205@jp.fujitsu.com> From: KOSAKI Motohiro Date: Thu, 4 Oct 2012 16:53:17 -0400 X-Google-Sender-Auth: Z-brJtr9ejgyLPFb6NuB5e5oSm4 Message-ID: Subject: Re: [PATCH 1/4] acpi,memory-hotplug : add memory offline code to acpi_memory_device_remove() To: Yasuaki Ishimatsu Cc: x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, rientjes@google.com, liuj97@gmail.com, len.brown@intel.com, cl@linux.com, minchan.kim@gmail.com, akpm@linux-foundation.org, wency@cn.fujitsu.com Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5350 Lines: 151 On Wed, Oct 3, 2012 at 5:58 AM, Yasuaki Ishimatsu wrote: > From: Yasuaki Ishimatsu > > The memory device can be removed by 2 ways: > 1. send eject request by SCI > 2. echo 1 >/sys/bus/pci/devices/PNP0C80:XX/eject > > In the 1st case, acpi_memory_disable_device() will be called. > In the 2nd case, acpi_memory_device_remove() will be called. > acpi_memory_device_remove() will also be called when we unbind the > memory device from the driver acpi_memhotplug. > > acpi_memory_disable_device() has already implemented a code which > offlines memory and releases acpi_memory_info struct . But > acpi_memory_device_remove() has not implemented it yet. > > So the patch implements acpi_memory_remove_memory() for offlining > memory and releasing acpi_memory_info struct. And it is used by both > acpi_memory_device_remove() and acpi_memory_disable_device(). > > Additionally, if the type is ACPI_BUS_REMOVAL_EJECT in > acpi_memory_device_remove() , it means that the user wants to eject > the memory device. In this case, acpi_memory_device_remove() calls > acpi_memory_remove_memory(). > > CC: David Rientjes > CC: Jiang Liu > CC: Len Brown > CC: Christoph Lameter > Cc: Minchan Kim > CC: Andrew Morton > CC: KOSAKI Motohiro > Signed-off-by: Yasuaki Ishimatsu > Signed-off-by: Wen Congyang > --- > drivers/acpi/acpi_memhotplug.c | 44 +++++++++++++++++++++++++++++++---------- > 1 file changed, 34 insertions(+), 10 deletions(-) > > Index: linux-3.6/drivers/acpi/acpi_memhotplug.c > =================================================================== > --- linux-3.6.orig/drivers/acpi/acpi_memhotplug.c 2012-10-03 18:55:33.386378909 +0900 > +++ linux-3.6/drivers/acpi/acpi_memhotplug.c 2012-10-03 18:55:58.624380688 +0900 > @@ -306,24 +306,37 @@ static int acpi_memory_powerdown_device( > return 0; > } > > -static int acpi_memory_disable_device(struct acpi_memory_device *mem_device) > +static int acpi_memory_remove_memory(struct acpi_memory_device *mem_device) > { > int result; > struct acpi_memory_info *info, *n; > > + list_for_each_entry_safe(info, n, &mem_device->res_list, list) { Which lock protect this loop? > + if (!info->enabled) > + return -EBUSY; > + > + result = remove_memory(info->start_addr, info->length); > + if (result) > + return result; I suspect you need to implement rollback code instead of just return. > + > + list_del(&info->list); > + kfree(info); > + } > + > + return 0; > +} > + > +static int acpi_memory_disable_device(struct acpi_memory_device *mem_device) > +{ > + int result; > > /* > * Ask the VM to offline this memory range. > * Note: Assume that this function returns zero on success > */ Write function comment instead of this silly comment. > - list_for_each_entry_safe(info, n, &mem_device->res_list, list) { > - if (info->enabled) { > - result = remove_memory(info->start_addr, info->length); > - if (result) > - return result; > - } > - kfree(info); > - } > + result = acpi_memory_remove_memory(mem_device); > + if (result) > + return result; > > /* Power-off and eject the device */ > result = acpi_memory_powerdown_device(mem_device); This patch move acpi_memory_powerdown_device() from ACPI_NOTIFY_EJECT_REQUEST to release callback, but don't explain why. > @@ -473,12 +486,23 @@ static int acpi_memory_device_add(struct > static int acpi_memory_device_remove(struct acpi_device *device, int type) > { > struct acpi_memory_device *mem_device = NULL; > - > + int result; > > if (!device || !acpi_driver_data(device)) > return -EINVAL; > > mem_device = acpi_driver_data(device); > + > + if (type == ACPI_BUS_REMOVAL_EJECT) { > + /* > + * offline and remove memory only when the memory device is > + * ejected. > + */ This comment explain nothing. A comment should describe _why_ should we do. e.g. Why REMOVAL_NORMAL and REMOVEL_EJECT should be ignored. Why we need remove memory here instead of ACPI_NOTIFY_EJECT_REQUEST. > + result = acpi_memory_remove_memory(mem_device); > + if (result) > + return result; > + } > + > kfree(mem_device); > > return 0; > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org -- 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/