Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
This commit is contained in:
Linus Torvalds
193
kernel/cpu.c
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193
kernel/cpu.c
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/* CPU control.
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* (C) 2001, 2002, 2003, 2004 Rusty Russell
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*
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* This code is licenced under the GPL.
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*/
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#include <linux/proc_fs.h>
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#include <linux/smp.h>
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#include <linux/init.h>
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#include <linux/notifier.h>
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#include <linux/sched.h>
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#include <linux/unistd.h>
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#include <linux/cpu.h>
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#include <linux/module.h>
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#include <linux/kthread.h>
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#include <linux/stop_machine.h>
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#include <asm/semaphore.h>
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/* This protects CPUs going up and down... */
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DECLARE_MUTEX(cpucontrol);
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static struct notifier_block *cpu_chain;
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/* Need to know about CPUs going up/down? */
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int register_cpu_notifier(struct notifier_block *nb)
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{
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int ret;
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if ((ret = down_interruptible(&cpucontrol)) != 0)
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return ret;
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ret = notifier_chain_register(&cpu_chain, nb);
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up(&cpucontrol);
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return ret;
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}
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EXPORT_SYMBOL(register_cpu_notifier);
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void unregister_cpu_notifier(struct notifier_block *nb)
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{
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down(&cpucontrol);
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notifier_chain_unregister(&cpu_chain, nb);
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up(&cpucontrol);
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}
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EXPORT_SYMBOL(unregister_cpu_notifier);
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#ifdef CONFIG_HOTPLUG_CPU
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static inline void check_for_tasks(int cpu)
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{
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struct task_struct *p;
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write_lock_irq(&tasklist_lock);
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for_each_process(p) {
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if (task_cpu(p) == cpu &&
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(!cputime_eq(p->utime, cputime_zero) ||
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!cputime_eq(p->stime, cputime_zero)))
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printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d\
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(state = %ld, flags = %lx) \n",
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p->comm, p->pid, cpu, p->state, p->flags);
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}
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write_unlock_irq(&tasklist_lock);
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}
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/* Take this CPU down. */
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static int take_cpu_down(void *unused)
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{
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int err;
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/* Take offline: makes arch_cpu_down somewhat easier. */
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cpu_clear(smp_processor_id(), cpu_online_map);
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/* Ensure this CPU doesn't handle any more interrupts. */
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err = __cpu_disable();
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if (err < 0)
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cpu_set(smp_processor_id(), cpu_online_map);
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else
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/* Force idle task to run as soon as we yield: it should
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immediately notice cpu is offline and die quickly. */
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sched_idle_next();
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return err;
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}
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int cpu_down(unsigned int cpu)
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{
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int err;
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struct task_struct *p;
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cpumask_t old_allowed, tmp;
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if ((err = lock_cpu_hotplug_interruptible()) != 0)
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return err;
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if (num_online_cpus() == 1) {
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err = -EBUSY;
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goto out;
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}
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if (!cpu_online(cpu)) {
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err = -EINVAL;
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goto out;
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}
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err = notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE,
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(void *)(long)cpu);
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if (err == NOTIFY_BAD) {
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printk("%s: attempt to take down CPU %u failed\n",
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__FUNCTION__, cpu);
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err = -EINVAL;
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goto out;
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}
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/* Ensure that we are not runnable on dying cpu */
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old_allowed = current->cpus_allowed;
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tmp = CPU_MASK_ALL;
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cpu_clear(cpu, tmp);
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set_cpus_allowed(current, tmp);
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p = __stop_machine_run(take_cpu_down, NULL, cpu);
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if (IS_ERR(p)) {
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/* CPU didn't die: tell everyone. Can't complain. */
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if (notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED,
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(void *)(long)cpu) == NOTIFY_BAD)
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BUG();
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err = PTR_ERR(p);
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goto out_allowed;
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}
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if (cpu_online(cpu))
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goto out_thread;
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/* Wait for it to sleep (leaving idle task). */
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while (!idle_cpu(cpu))
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yield();
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/* This actually kills the CPU. */
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__cpu_die(cpu);
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/* Move it here so it can run. */
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kthread_bind(p, get_cpu());
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put_cpu();
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/* CPU is completely dead: tell everyone. Too late to complain. */
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if (notifier_call_chain(&cpu_chain, CPU_DEAD, (void *)(long)cpu)
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== NOTIFY_BAD)
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BUG();
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check_for_tasks(cpu);
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out_thread:
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err = kthread_stop(p);
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out_allowed:
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set_cpus_allowed(current, old_allowed);
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out:
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unlock_cpu_hotplug();
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return err;
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}
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#endif /*CONFIG_HOTPLUG_CPU*/
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int __devinit cpu_up(unsigned int cpu)
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{
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int ret;
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void *hcpu = (void *)(long)cpu;
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if ((ret = down_interruptible(&cpucontrol)) != 0)
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return ret;
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if (cpu_online(cpu) || !cpu_present(cpu)) {
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ret = -EINVAL;
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goto out;
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}
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ret = notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu);
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if (ret == NOTIFY_BAD) {
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printk("%s: attempt to bring up CPU %u failed\n",
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__FUNCTION__, cpu);
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ret = -EINVAL;
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goto out_notify;
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}
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/* Arch-specific enabling code. */
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ret = __cpu_up(cpu);
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if (ret != 0)
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goto out_notify;
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if (!cpu_online(cpu))
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BUG();
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/* Now call notifier in preparation. */
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notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu);
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out_notify:
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if (ret != 0)
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notifier_call_chain(&cpu_chain, CPU_UP_CANCELED, hcpu);
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out:
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up(&cpucontrol);
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return ret;
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}
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