1 files changed, 38 insertions, 1 deletions

diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
index aea2ce1145df..c1b11e8df60b 100644
--- a/arch/i386/kernel/process.c
+++ b/arch/i386/kernel/process.c
@@ -13,6 +13,7 @@
 
 #include <stdarg.h>
 
+#include <linux/cpu.h>
 #include <linux/errno.h>
 #include <linux/sched.h>
 #include <linux/fs.h>
@@ -55,6 +56,9 @@
 #include <linux/irq.h>
 #include <linux/err.h>
 
+#include <asm/tlbflush.h>
+#include <asm/cpu.h>
+
 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
 
 static int hlt_counter;
@@ -143,14 +147,44 @@ static void poll_idle (void)
         }
 }
 
+#ifdef CONFIG_HOTPLUG_CPU
+#include <asm/nmi.h>
+/* We don't actually take CPU down, just spin without interrupts. */
+static inline void play_dead(void)
+{
+        /* Ack it */
+        __get_cpu_var(cpu_state) = CPU_DEAD;
+
+        /* We shouldn't have to disable interrupts while dead, but
+         * some interrupts just don't seem to go away, and this makes
+         * it "work" for testing purposes. */
+        /* Death loop */
+        while (__get_cpu_var(cpu_state) != CPU_UP_PREPARE)
+                cpu_relax();
+
+        local_irq_disable();
+        __flush_tlb_all();
+        cpu_set(smp_processor_id(), cpu_online_map);
+        enable_APIC_timer();
+        local_irq_enable();
+}
+#else
+static inline void play_dead(void)
+{
+        BUG();
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
 /*
  * The idle thread. There's no useful work to be
  * done, so just try to conserve power and have a
  * low exit latency (ie sit in a loop waiting for
  * somebody to say that they'd like to reschedule)
  */
-void cpu_idle (void)
+void cpu_idle(void)
 {
+        int cpu = raw_smp_processor_id();
+
         /* endless idle loop with no priority at all */
         while (1) {
                 while (!need_resched()) {
@@ -165,6 +199,9 @@ void cpu_idle (void)
                         if (!idle)
                                 idle = default_idle;
 
+                        if (cpu_is_offline(cpu))
+                                play_dead();
+
                         __get_cpu_var(irq_stat).idle_timestamp = jiffies;
                         idle();
                 }