1 files changed, 93 insertions, 5 deletions

diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c
index c20d96d5c15c..ad74a46e9ef0 100644
--- a/arch/i386/kernel/smpboot.c
+++ b/arch/i386/kernel/smpboot.c
@@ -44,6 +44,9 @@
 #include <linux/smp_lock.h>
 #include <linux/irq.h>
 #include <linux/bootmem.h>
+#include <linux/notifier.h>
+#include <linux/cpu.h>
+#include <linux/percpu.h>
 
 #include <linux/delay.h>
 #include <linux/mc146818rtc.h>
@@ -96,6 +99,9 @@ static int trampoline_exec;
 
 static void map_cpu_to_logical_apicid(void);
 
+/* State of each CPU. */
+DEFINE_PER_CPU(int, cpu_state) = { 0 };
+
 /*
  * Currently trivial. Write the real->protected mode
  * bootstrap into the page concerned. The caller
@@ -1119,6 +1125,9 @@ static void __init smp_boot_cpus(unsigned int max_cpus)
    who understands all this stuff should rewrite it properly. --RR 15/Jul/02 */
 void __init smp_prepare_cpus(unsigned int max_cpus)
 {
+        smp_commenced_mask = cpumask_of_cpu(0);
+        cpu_callin_map = cpumask_of_cpu(0);
+        mb();
         smp_boot_cpus(max_cpus);
 }
 
@@ -1128,20 +1137,99 @@ void __devinit smp_prepare_boot_cpu(void)
         cpu_set(smp_processor_id(), cpu_callout_map);
 }
 
-int __devinit __cpu_up(unsigned int cpu)
+#ifdef CONFIG_HOTPLUG_CPU
+
+/* must be called with the cpucontrol mutex held */
+static int __devinit cpu_enable(unsigned int cpu)
 {
-        /* This only works at boot for x86.  See "rewrite" above. */
-        if (cpu_isset(cpu, smp_commenced_mask)) {
-                local_irq_enable();
-                return -ENOSYS;
+        /* get the target out of its holding state */
+        per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
+        wmb();
+
+        /* wait for the processor to ack it. timeout? */
+        while (!cpu_online(cpu))
+                cpu_relax();
+
+        fixup_irqs(cpu_online_map);
+        /* counter the disable in fixup_irqs() */
+        local_irq_enable();
+        return 0;
+}
+
+int __cpu_disable(void)
+{
+        cpumask_t map = cpu_online_map;
+        int cpu = smp_processor_id();
+
+        /*
+         * Perhaps use cpufreq to drop frequency, but that could go
+         * into generic code.
+         *
+         * We won't take down the boot processor on i386 due to some
+         * interrupts only being able to be serviced by the BSP.
+         * Especially so if we're not using an IOAPIC   -zwane
+         */
+        if (cpu == 0)
+                return -EBUSY;
+
+        /* We enable the timer again on the exit path of the death loop */
+        disable_APIC_timer();
+        /* Allow any queued timer interrupts to get serviced */
+        local_irq_enable();
+        mdelay(1);
+        local_irq_disable();
+
+        cpu_clear(cpu, map);
+        fixup_irqs(map);
+        /* It's now safe to remove this processor from the online map */
+        cpu_clear(cpu, cpu_online_map);
+        return 0;
+}
+
+void __cpu_die(unsigned int cpu)
+{
+        /* We don't do anything here: idle task is faking death itself. */
+        unsigned int i;
+
+        for (i = 0; i < 10; i++) {
+                /* They ack this in play_dead by setting CPU_DEAD */
+                if (per_cpu(cpu_state, cpu) == CPU_DEAD)
+                        return;
+                current->state = TASK_UNINTERRUPTIBLE;
+                schedule_timeout(HZ/10);
         }
+        printk(KERN_ERR "CPU %u didn't die...\n", cpu);
+}
+#else /* ... !CONFIG_HOTPLUG_CPU */
+int __cpu_disable(void)
+{
+        return -ENOSYS;
+}
 
+void __cpu_die(unsigned int cpu)
+{
+        /* We said "no" in __cpu_disable */
+        BUG();
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
+int __devinit __cpu_up(unsigned int cpu)
+{
         /* In case one didn't come up */
         if (!cpu_isset(cpu, cpu_callin_map)) {
+                printk(KERN_DEBUG "skipping cpu%d, didn't come online\n", cpu);
                 local_irq_enable();
                 return -EIO;
         }
 
+#ifdef CONFIG_HOTPLUG_CPU
+        /* Already up, and in cpu_quiescent now? */
+        if (cpu_isset(cpu, smp_commenced_mask)) {
+                cpu_enable(cpu);
+                return 0;
+        }
+#endif
+
         local_irq_enable();
         /* Unleash the CPU! */
         cpu_set(cpu, smp_commenced_mask);