Merge branch 'linus' into core/rcu

1 files changed, 45 insertions, 0 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index f928f2a87b9..d4dc69ddebd 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -970,6 +970,51 @@ undo:
         return ret;
 }
 
+#ifdef CONFIG_SMP
+struct work_for_cpu {
+        struct work_struct work;
+        long (*fn)(void *);
+        void *arg;
+        long ret;
+};
+
+static void do_work_for_cpu(struct work_struct *w)
+{
+        struct work_for_cpu *wfc = container_of(w, struct work_for_cpu, work);
+
+        wfc->ret = wfc->fn(wfc->arg);
+}
+
+/**
+ * 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 */
+
 void __init init_workqueues(void)
 {
         cpu_populated_map = cpu_online_map;