diff options
Diffstat (limited to 'kernel/cpu.c')
| -rw-r--r-- | kernel/cpu.c | 193 |
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; +} |