Messages in this thread | | | Date | Thu, 29 Sep 2011 11:41:35 +0800 | From | "canquan.shen" <> | Subject | Re: [PATCH v5] acpi: Fix CPU hot removal problem |
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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 <n>) 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 <shencanquan@huawei.com> >> --- >> 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.
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