Fix SMP boot for kernels without CONFIG_HOTPLUG_CPU.

The function cpu_is_allowed() appears that it should return a boolean
but in fact returns zero on success and an errno on failure. Thus
rename it to the more vague cpu_up_check(), in line with its return
value and thge fact it has unspecified side effects.

Fix the macro definition of cpu_up_check() when building non-hotplug
kernel to return zero rather than one (which always failed secondary
cpu bringup!).

Signed-off-by: Keir Fraser <keir@xensource.com>

linux-2.6-xen-sparse/drivers/xen/core/cpu_hotplug.c

@@ -160,7 +160,7 @@ void smp_resume(void)
 		vcpu_hotplug(cpu);
 }
 
-int cpu_up_is_allowed(unsigned int cpu)
+int cpu_up_check(unsigned int cpu)
 {
 	int rc = 0;
 

linux-2.6-xen-sparse/drivers/xen/core/smpboot.c

@@ -400,7 +400,7 @@ int __devinit __cpu_up(unsigned int cpu)
 {
 	int rc;
 
-	rc = cpu_up_is_allowed(cpu);
+	rc = cpu_up_check(cpu);
 	if (rc)
 		return rc;
 

linux-2.6-xen-sparse/include/xen/cpu_hotplug.h

@@ -13,14 +13,14 @@ void cpu_initialize_context(unsigned int cpu);
 #define cpu_initialize_context(cpu)	((void)0)
 #endif
 
-int cpu_up_is_allowed(unsigned int cpu);
+int cpu_up_check(unsigned int cpu);
 void init_xenbus_allowed_cpumask(void);
 int smp_suspend(void);
 void smp_resume(void);
 
 #else /* !defined(CONFIG_HOTPLUG_CPU) */
 
-#define cpu_up_is_allowed(cpu)		(1)
+#define cpu_up_check(cpu)		(0)
 #define init_xenbus_allowed_cpumask()	((void)0)
 
 static inline int smp_suspend(void)