X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=kernel%2Fcpu.c;h=fe2b8d0bfe4ce3c76403b623b74307661a1a151f;hb=9464c7cf61b9433057924c36e6e02f303a00e768;hp=fcbb0d5d2817ea5451b60431f66344500095b3d8;hpb=daddc0d38b3571bed170afa273a49a0eba090c1e;p=linux-2.6.git diff --git a/kernel/cpu.c b/kernel/cpu.c index fcbb0d5d2..fe2b8d0bf 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -11,101 +11,114 @@ #include #include #include -#include /* for hotplug_path */ #include #include #include /* This protects CPUs going up and down... */ -DECLARE_MUTEX(cpucontrol); +static DECLARE_MUTEX(cpucontrol); -static struct notifier_block *cpu_chain; +static BLOCKING_NOTIFIER_HEAD(cpu_chain); -/* Need to know about CPUs going up/down? */ -int register_cpu_notifier(struct notifier_block *nb) +#ifdef CONFIG_HOTPLUG_CPU +static struct task_struct *lock_cpu_hotplug_owner; +static int lock_cpu_hotplug_depth; + +static int __lock_cpu_hotplug(int interruptible) { - int ret; + int ret = 0; + + if (lock_cpu_hotplug_owner != current) { + if (interruptible) + ret = down_interruptible(&cpucontrol); + else + down(&cpucontrol); + } + + /* + * Set only if we succeed in locking + */ + if (!ret) { + lock_cpu_hotplug_depth++; + lock_cpu_hotplug_owner = current; + } - if ((ret = down_interruptible(&cpucontrol)) != 0) - return ret; - ret = notifier_chain_register(&cpu_chain, nb); - up(&cpucontrol); return ret; } + +void lock_cpu_hotplug(void) +{ + __lock_cpu_hotplug(0); +} +EXPORT_SYMBOL_GPL(lock_cpu_hotplug); + +void unlock_cpu_hotplug(void) +{ + if (--lock_cpu_hotplug_depth == 0) { + lock_cpu_hotplug_owner = NULL; + up(&cpucontrol); + } +} +EXPORT_SYMBOL_GPL(unlock_cpu_hotplug); + +int lock_cpu_hotplug_interruptible(void) +{ + return __lock_cpu_hotplug(1); +} +EXPORT_SYMBOL_GPL(lock_cpu_hotplug_interruptible); +#endif /* CONFIG_HOTPLUG_CPU */ + +/* Need to know about CPUs going up/down? */ +int register_cpu_notifier(struct notifier_block *nb) +{ + return blocking_notifier_chain_register(&cpu_chain, nb); +} EXPORT_SYMBOL(register_cpu_notifier); void unregister_cpu_notifier(struct notifier_block *nb) { - down(&cpucontrol); - notifier_chain_unregister(&cpu_chain, nb); - up(&cpucontrol); + blocking_notifier_chain_unregister(&cpu_chain, nb); } EXPORT_SYMBOL(unregister_cpu_notifier); #ifdef CONFIG_HOTPLUG_CPU -static inline void check_for_tasks(int cpu, struct task_struct *k) +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 != k) - printk(KERN_WARNING "Task %s is on cpu %d\n", - p->comm, cpu); + 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); } -/* 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 - /* Everyone else gets kicked off. */ - migrate_all_tasks(); + return err; - return err; + /* Force idle task to run as soon as we yield: it should + immediately notice cpu is offline and die quickly. */ + sched_idle_next(); + return 0; } 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; @@ -120,17 +133,35 @@ int cpu_down(unsigned int cpu) goto out; } + err = blocking_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 (blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED, + (void *)(long)cpu) == NOTIFY_BAD) + BUG(); + err = PTR_ERR(p); - goto out; + goto out_allowed; } if (cpu_online(cpu)) goto out_thread; - check_for_tasks(cpu, p); - /* Wait for it to sleep (leaving idle task). */ while (!idle_cpu(cpu)) yield(); @@ -139,26 +170,24 @@ int cpu_down(unsigned int cpu) __cpu_die(cpu); /* Move it here so it can run. */ - kthread_bind(p, smp_processor_id()); + 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) + if (blocking_notifier_call_chain(&cpu_chain, CPU_DEAD, + (void *)(long)cpu) == NOTIFY_BAD) BUG(); - cpu_run_sbin_hotplug(cpu, "offline"); + check_for_tasks(cpu); 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) @@ -166,14 +195,15 @@ int __devinit cpu_up(unsigned int cpu) int ret; void *hcpu = (void *)(long)cpu; - if ((ret = down_interruptible(&cpucontrol)) != 0) + if ((ret = lock_cpu_hotplug_interruptible()) != 0) return ret; - if (cpu_online(cpu)) { + if (cpu_online(cpu) || !cpu_present(cpu)) { ret = -EINVAL; goto out; } - ret = notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu); + + ret = blocking_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); @@ -185,16 +215,16 @@ int __devinit cpu_up(unsigned int cpu) ret = __cpu_up(cpu); if (ret != 0) goto out_notify; - if (!cpu_online(cpu)) - BUG(); + BUG_ON(!cpu_online(cpu)); /* Now call notifier in preparation. */ - notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu); + blocking_notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu); out_notify: if (ret != 0) - notifier_call_chain(&cpu_chain, CPU_UP_CANCELED, hcpu); + blocking_notifier_call_chain(&cpu_chain, + CPU_UP_CANCELED, hcpu); out: - up(&cpucontrol); + unlock_cpu_hotplug(); return ret; }