+/**
+ * work_on_cpu - run a function in user context on a particular cpu
+ * @cpu: the cpu to run on
+ * @fn: the function to run
+ * @arg: the function arg
+ *
+ * This will return -EINVAL in the cpu is not online, or the return value
+ * of @fn otherwise.
+ */
+long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
+{
+ struct work_for_cpu wfc;
+
+ INIT_WORK(&wfc.work, do_work_for_cpu);
+ wfc.fn = fn;
+ wfc.arg = arg;
+ get_online_cpus();
+ if (unlikely(!cpu_online(cpu)))
+ wfc.ret = -EINVAL;
+ else {
+ schedule_work_on(cpu, &wfc.work);
+ flush_work(&wfc.work);
+ }
+ put_online_cpus();
+
+ return wfc.ret;
+}
+EXPORT_SYMBOL_GPL(work_on_cpu);
+#endif /* CONFIG_SMP */
+