create sysfs link from acpi device to sysdev for cpu

Sys I/F under acpi device node and sysdev device node are both
needed for cpu hot-removal. User space need this link so that
they know they are poking the sys I/F for the same cpu.
http://bugzilla.kernel.org/show_bug.cgi?id=9772

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c
index 1c0008edccda..feddc8ed870a 100644
--- a/drivers/acpi/processor_core.c
+++ b/drivers/acpi/processor_core.c
@@ -621,7 +621,7 @@ static int __cpuinit acpi_processor_start(struct acpi_device *device)
         int result = 0;
         acpi_status status = AE_OK;
         struct acpi_processor *pr;
-
+        struct sys_device *sysdev;
 
         pr = acpi_driver_data(device);
 
@@ -652,6 +652,10 @@ static int __cpuinit acpi_processor_start(struct acpi_device *device)
         if (result)
                 goto end;
 
+        sysdev = get_cpu_sysdev(pr->id);
+        if (sysfs_create_link(&device->dev.kobj, &sysdev->kobj, "sysdev"))
+                return -EFAULT;
+
         status = acpi_install_notify_handler(pr->handle, ACPI_DEVICE_NOTIFY,
                                              acpi_processor_notify, pr);
 
@@ -810,6 +814,8 @@ static int acpi_processor_remove(struct acpi_device *device, int type)
         status = acpi_remove_notify_handler(pr->handle, ACPI_DEVICE_NOTIFY,
                                             acpi_processor_notify);
 
+        sysfs_remove_link(&device->dev.kobj, "sysdev");
+
         acpi_processor_remove_fs(device);
 
         if (pr->cdev) {