1 files changed, 62 insertions, 0 deletions

diff --git a/kernel/smpboot.c b/kernel/smpboot.c
new file mode 100644
index 000000000000..e1a797e028a3
--- /dev/null
+++ b/kernel/smpboot.c
@@ -0,0 +1,62 @@
+/*
+ * Common SMP CPU bringup/teardown functions
+ */
+#include <linux/err.h>
+#include <linux/smp.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/percpu.h>
+
+#include "smpboot.h"
+
+#ifdef CONFIG_GENERIC_SMP_IDLE_THREAD
+/*
+ * For the hotplug case we keep the task structs around and reuse
+ * them.
+ */
+static DEFINE_PER_CPU(struct task_struct *, idle_threads);
+
+struct task_struct * __cpuinit idle_thread_get(unsigned int cpu)
+{
+        struct task_struct *tsk = per_cpu(idle_threads, cpu);
+
+        if (!tsk)
+                return ERR_PTR(-ENOMEM);
+        init_idle(tsk, cpu);
+        return tsk;
+}
+
+void __init idle_thread_set_boot_cpu(void)
+{
+        per_cpu(idle_threads, smp_processor_id()) = current;
+}
+
+static inline void idle_init(unsigned int cpu)
+{
+        struct task_struct *tsk = per_cpu(idle_threads, cpu);
+
+        if (!tsk) {
+                tsk = fork_idle(cpu);
+                if (IS_ERR(tsk))
+                        pr_err("SMP: fork_idle() failed for CPU %u\n", cpu);
+                else
+                        per_cpu(idle_threads, cpu) = tsk;
+        }
+}
+
+/**
+ * idle_thread_init - Initialize the idle thread for a cpu
+ * @cpu:        The cpu for which the idle thread should be initialized
+ *
+ * Creates the thread if it does not exist.
+ */
+void __init idle_threads_init(void)
+{
+        unsigned int cpu;
+
+        for_each_possible_cpu(cpu) {
+                if (cpu != smp_processor_id())
+                        idle_init(cpu);
+        }
+}
+#endif