force offline the processor during hot-removal

The ACPI device node for the cpu has already been unregistered
when acpi_processor_handle_eject is called.
Thus we should offline the cpu and continue, rather than a failure here.
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>

drivers/acpi/processor_core.c

@@ -1014,9 +1014,9 @@ static acpi_status acpi_processor_hotadd_init(acpi_handle handle, int *p_cpu)
 
 static int acpi_processor_handle_eject(struct acpi_processor *pr)
 {
-	if (cpu_online(pr->id)) {
-		return (-EINVAL);
-	}
+	if (cpu_online(pr->id))
+		cpu_down(pr->id);
+
 	arch_unregister_cpu(pr->id);
 	acpi_unmap_lsapic(pr->id);
 	return (0);

kernel/cpu.c

@@ -299,6 +299,7 @@ int __ref cpu_down(unsigned int cpu)
 	cpu_maps_update_done();
 	return err;
 }
+EXPORT_SYMBOL(cpu_down);
 #endif /*CONFIG_HOTPLUG_CPU*/
 
 /* Requires cpu_add_remove_lock to be held */