this warning:
  kernel/hrtimer.c: In function ‘hrtimer_cpu_notify’:
  kernel/hrtimer.c:1574: warning: unused variable ‘dcpu’
is caused because 'dcpu' is only used in the CONFIG_HOTPLUG_CPU case.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
 static int __cpuinit hrtimer_cpu_notify(struct notifier_block *self,
                                        unsigned long action, void *hcpu)
 {
-       int dcpu, scpu = (long)hcpu;
+       int scpu = (long)hcpu;
 
        switch (action) {
 
 #ifdef CONFIG_HOTPLUG_CPU
        case CPU_DEAD:
        case CPU_DEAD_FROZEN:
+       {
+               int dcpu;
+
                clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DEAD, &scpu);
                dcpu = migrate_hrtimers(scpu);
                smp_call_function_single(dcpu, tickle_timers, NULL, 0);
                break;
+       }
 #endif
 
        default: