[PATCH] make smp_prepare_cpu to a weak function

I really wish smp_prepare_cpu() would disappear eventually.  In the interim
this is ideally a weak function, so we dont end up changing several places
to define this dummy in headers.

Today since the dummy declaration is done only in drivers/base/cpu.c but
the function is called in kernel/power/smp.c i get undefined reference in
my cpu hotplug code for x86_64 under development.

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 6 insertions, 7 deletions

diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index bdd7e9f55c81..0bf2dc11cdb8 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -16,9 +16,10 @@ struct sysdev_class cpu_sysdev_class = {
 EXPORT_SYMBOL(cpu_sysdev_class);
 
 #ifdef CONFIG_HOTPLUG_CPU
-#ifndef __HAVE_ARCH_SMP_PREPARE_CPU
-#define smp_prepare_cpu(cpu) (0)
-#endif
+int __attribute__((weak)) smp_prepare_cpu (int cpu)
+{
+        return 0;
+}
 
 static ssize_t show_online(struct sys_device *dev, char *buf)
 {
@@ -41,7 +42,7 @@ static ssize_t store_online(struct sys_device *dev, const char *buf,
                 break;
         case '1':
                 ret = smp_prepare_cpu(cpu->sysdev.id);
-                if (ret == 0)
+                if (!ret)
                         ret = cpu_up(cpu->sysdev.id);
                 break;
         default:
diff --git a/include/asm-i386/smp.h b/include/asm-i386/smp.h
index c9996eda5408..edad9b4712fa 100644
--- a/include/asm-i386/smp.h
+++ b/include/asm-i386/smp.h
@@ -51,9 +51,6 @@ extern u8 x86_cpu_to_apicid[];
 #ifdef CONFIG_HOTPLUG_CPU
 extern void cpu_exit_clear(void);
 extern void cpu_uninit(void);
-
-#define __HAVE_ARCH_SMP_PREPARE_CPU
-extern int smp_prepare_cpu(int cpu);
 #endif
 
 /*
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index fe0298e5dae1..e8904c0da686 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -69,6 +69,7 @@ extern struct semaphore cpucontrol;
         register_cpu_notifier(&fn##_nb);                        \
 }
 int cpu_down(unsigned int cpu);
+extern int __attribute__((weak)) smp_prepare_cpu(int cpu);
 #define cpu_is_offline(cpu) unlikely(!cpu_online(cpu))
 #else
 #define lock_cpu_hotplug()      do { } while (0)