1 files changed, 193 insertions, 0 deletions

diff --git a/kernel/cpu.c b/kernel/cpu.c
new file mode 100644
index 000000000000..628f4ccda127
--- /dev/null
+++ b/kernel/cpu.c
@@ -0,0 +1,193 @@
+/* CPU control.
+ * (C) 2001, 2002, 2003, 2004 Rusty Russell
+ *
+ * This code is licenced under the GPL.
+ */
+#include <linux/proc_fs.h>
+#include <linux/smp.h>
+#include <linux/init.h>
+#include <linux/notifier.h>
+#include <linux/sched.h>
+#include <linux/unistd.h>
+#include <linux/cpu.h>
+#include <linux/module.h>
+#include <linux/kthread.h>
+#include <linux/stop_machine.h>
+#include <asm/semaphore.h>
+
+/* This protects CPUs going up and down... */
+DECLARE_MUTEX(cpucontrol);
+
+static struct notifier_block *cpu_chain;
+
+/* Need to know about CPUs going up/down? */
+int register_cpu_notifier(struct notifier_block *nb)
+{
+        int ret;
+
+        if ((ret = down_interruptible(&cpucontrol)) != 0)
+                return ret;
+        ret = notifier_chain_register(&cpu_chain, nb);
+        up(&cpucontrol);
+        return ret;
+}
+EXPORT_SYMBOL(register_cpu_notifier);
+
+void unregister_cpu_notifier(struct notifier_block *nb)
+{
+        down(&cpucontrol);
+        notifier_chain_unregister(&cpu_chain, nb);
+        up(&cpucontrol);
+}
+EXPORT_SYMBOL(unregister_cpu_notifier);
+
+#ifdef CONFIG_HOTPLUG_CPU
+static inline void check_for_tasks(int cpu)
+{
+        struct task_struct *p;
+
+        write_lock_irq(&tasklist_lock);
+        for_each_process(p) {
+                if (task_cpu(p) == cpu &&
+                    (!cputime_eq(p->utime, cputime_zero) ||
+                     !cputime_eq(p->stime, cputime_zero)))
+                        printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d\
+                                (state = %ld, flags = %lx) \n",
+                                 p->comm, p->pid, cpu, p->state, p->flags);
+        }
+        write_unlock_irq(&tasklist_lock);
+}
+
+/* Take this CPU down. */
+static int take_cpu_down(void *unused)
+{
+        int err;
+
+        /* Take offline: makes arch_cpu_down somewhat easier. */
+        cpu_clear(smp_processor_id(), cpu_online_map);
+
+        /* Ensure this CPU doesn't handle any more interrupts. */
+        err = __cpu_disable();
+        if (err < 0)
+                cpu_set(smp_processor_id(), cpu_online_map);
+        else
+                /* Force idle task to run as soon as we yield: it should
+                   immediately notice cpu is offline and die quickly. */
+                sched_idle_next();
+
+        return err;
+}
+
+int cpu_down(unsigned int cpu)
+{
+        int err;
+        struct task_struct *p;
+        cpumask_t old_allowed, tmp;
+
+        if ((err = lock_cpu_hotplug_interruptible()) != 0)
+                return err;
+
+        if (num_online_cpus() == 1) {
+                err = -EBUSY;
+                goto out;
+        }
+
+        if (!cpu_online(cpu)) {
+                err = -EINVAL;
+                goto out;
+        }
+
+        err = notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE,
+                                                (void *)(long)cpu);
+        if (err == NOTIFY_BAD) {
+                printk("%s: attempt to take down CPU %u failed\n",
+                                __FUNCTION__, cpu);
+                err = -EINVAL;
+                goto out;
+        }
+
+        /* Ensure that we are not runnable on dying cpu */
+        old_allowed = current->cpus_allowed;
+        tmp = CPU_MASK_ALL;
+        cpu_clear(cpu, tmp);
+        set_cpus_allowed(current, tmp);
+
+        p = __stop_machine_run(take_cpu_down, NULL, cpu);
+        if (IS_ERR(p)) {
+                /* CPU didn't die: tell everyone.  Can't complain. */
+                if (notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED,
+                                (void *)(long)cpu) == NOTIFY_BAD)
+                        BUG();
+
+                err = PTR_ERR(p);
+                goto out_allowed;
+        }
+
+        if (cpu_online(cpu))
+                goto out_thread;
+
+        /* Wait for it to sleep (leaving idle task). */
+        while (!idle_cpu(cpu))
+                yield();
+
+        /* This actually kills the CPU. */
+        __cpu_die(cpu);
+
+        /* Move it here so it can run. */
+        kthread_bind(p, get_cpu());
+        put_cpu();
+
+        /* CPU is completely dead: tell everyone.  Too late to complain. */
+        if (notifier_call_chain(&cpu_chain, CPU_DEAD, (void *)(long)cpu)
+            == NOTIFY_BAD)
+                BUG();
+
+        check_for_tasks(cpu);
+
+out_thread:
+        err = kthread_stop(p);
+out_allowed:
+        set_cpus_allowed(current, old_allowed);
+out:
+        unlock_cpu_hotplug();
+        return err;
+}
+#endif /*CONFIG_HOTPLUG_CPU*/
+
+int __devinit cpu_up(unsigned int cpu)
+{
+        int ret;
+        void *hcpu = (void *)(long)cpu;
+
+        if ((ret = down_interruptible(&cpucontrol)) != 0)
+                return ret;
+
+        if (cpu_online(cpu) || !cpu_present(cpu)) {
+                ret = -EINVAL;
+                goto out;
+        }
+        ret = notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu);
+        if (ret == NOTIFY_BAD) {
+                printk("%s: attempt to bring up CPU %u failed\n",
+                                __FUNCTION__, cpu);
+                ret = -EINVAL;
+                goto out_notify;
+        }
+
+        /* Arch-specific enabling code. */
+        ret = __cpu_up(cpu);
+        if (ret != 0)
+                goto out_notify;
+        if (!cpu_online(cpu))
+                BUG();
+
+        /* Now call notifier in preparation. */
+        notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu);
+
+out_notify:
+        if (ret != 0)
+                notifier_call_chain(&cpu_chain, CPU_UP_CANCELED, hcpu);
+out:
+        up(&cpucontrol);
+        return ret;
+}