+++ /dev/null
-/* 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/kmod.h> /* for hotplug_path */
-#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 && (p->utime != 0 || p->stime != 0))
- 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);
-}
-
-/* Notify userspace when a cpu event occurs, by running '/sbin/hotplug
- * cpu' with certain environment variables set. */
-static int cpu_run_sbin_hotplug(unsigned int cpu, const char *action)
-{
- char *argv[3], *envp[5], cpu_str[12], action_str[32];
- int i;
-
- sprintf(cpu_str, "CPU=%d", cpu);
- sprintf(action_str, "ACTION=%s", action);
- /* FIXME: Add DEVPATH. --RR */
-
- i = 0;
- argv[i++] = hotplug_path;
- argv[i++] = "cpu";
- argv[i] = NULL;
-
- i = 0;
- /* minimal command environment */
- envp[i++] = "HOME=/";
- envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
- envp[i++] = cpu_str;
- envp[i++] = action_str;
- envp[i] = NULL;
-
- return call_usermodehelper(argv[0], argv, envp, 0);
-}
-
-/* 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;
- }
-
- /* 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)) {
- 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, smp_processor_id());
-
- /* 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);
-
- cpu_run_sbin_hotplug(cpu, "offline");
-
-out_thread:
- err = kthread_stop(p);
-out_allowed:
- set_cpus_allowed(current, old_allowed);
-out:
- unlock_cpu_hotplug();
- return err;
-}
-#else
-static inline int cpu_run_sbin_hotplug(unsigned int cpu, const char *action)
-{
- return 0;
-}
-#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;
-}