[PATCH] revert the "remove kernel_flag" patch

With CONFIG_SMP=n, CONFIG_PREEMPT=y, CONFIG_DEBUG_SPINLOCK=y we get many
undefined refs to kernel_flag.

This is because spinlock debugging works on uniprocessor kernels now, and it
stores state inside the spinlock structure to do this.

Having working spinlock debugging on UP kernels seems more important than
saving four bytes, so...

kernel/ksyms.c

@@ -485,6 +485,8 @@ EXPORT_SYMBOL(task_nice);
 EXPORT_SYMBOL_GPL(idle_cpu);
 #if CONFIG_SMP
 EXPORT_SYMBOL_GPL(set_cpus_allowed);
+#endif
+#if CONFIG_SMP || CONFIG_PREEMPT
 EXPORT_SYMBOL(kernel_flag);
 #endif
 EXPORT_SYMBOL(jiffies);

kernel/sched.c

@@ -2426,7 +2426,7 @@ __init int migration_init(void)
 
 #endif
 
-#if CONFIG_SMP
+#if CONFIG_SMP || CONFIG_PREEMPT
 /*
  * The 'big kernel lock'
  *