X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=kernel%2Fcpu.c;h=7406fe6966f908cb547fba3de5fcf5d566f831ea;hb=97bf2856c6014879bd04983a3e9dfcdac1e7fe85;hp=e882c6babf414854a53b615229e49005d3cc4d75;hpb=76828883507a47dae78837ab5dec5a5b4513c667;p=linux-2.6.git diff --git a/kernel/cpu.c b/kernel/cpu.c index e882c6bab..7406fe696 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -13,83 +13,80 @@ #include #include #include -#include +#include /* This protects CPUs going up and down... */ -static DECLARE_MUTEX(cpucontrol); +static DEFINE_MUTEX(cpu_add_remove_lock); +static DEFINE_MUTEX(cpu_bitmask_lock); -static struct notifier_block *cpu_chain; +static __cpuinitdata RAW_NOTIFIER_HEAD(cpu_chain); -#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 = 0; +/* If set, cpu_up and cpu_down will return -EBUSY and do nothing. + * Should always be manipulated under cpu_add_remove_lock + */ +static int cpu_hotplug_disabled; - if (lock_cpu_hotplug_owner != current) { - if (interruptible) - ret = down_interruptible(&cpucontrol); - else - down(&cpucontrol); - } +#ifdef CONFIG_HOTPLUG_CPU - /* - * Set only if we succeed in locking - */ - if (!ret) { - lock_cpu_hotplug_depth++; - lock_cpu_hotplug_owner = current; - } - - return ret; -} +/* Crappy recursive lock-takers in cpufreq! Complain loudly about idiots */ +static struct task_struct *recursive; +static int recursive_depth; void lock_cpu_hotplug(void) { - __lock_cpu_hotplug(0); + struct task_struct *tsk = current; + + if (tsk == recursive) { + static int warnings = 10; + if (warnings) { + printk(KERN_ERR "Lukewarm IQ detected in hotplug locking\n"); + WARN_ON(1); + warnings--; + } + recursive_depth++; + return; + } + mutex_lock(&cpu_bitmask_lock); + recursive = tsk; } EXPORT_SYMBOL_GPL(lock_cpu_hotplug); void unlock_cpu_hotplug(void) { - if (--lock_cpu_hotplug_depth == 0) { - lock_cpu_hotplug_owner = NULL; - up(&cpucontrol); + WARN_ON(recursive != current); + if (recursive_depth) { + recursive_depth--; + return; } + recursive = NULL; + mutex_unlock(&cpu_bitmask_lock); } 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) +int __cpuinit register_cpu_notifier(struct notifier_block *nb) { int ret; - - if ((ret = lock_cpu_hotplug_interruptible()) != 0) - return ret; - ret = notifier_chain_register(&cpu_chain, nb); - unlock_cpu_hotplug(); + mutex_lock(&cpu_add_remove_lock); + ret = raw_notifier_chain_register(&cpu_chain, nb); + mutex_unlock(&cpu_add_remove_lock); return ret; } + +#ifdef CONFIG_HOTPLUG_CPU + EXPORT_SYMBOL(register_cpu_notifier); void unregister_cpu_notifier(struct notifier_block *nb) { - lock_cpu_hotplug(); - notifier_chain_unregister(&cpu_chain, nb); - unlock_cpu_hotplug(); + mutex_lock(&cpu_add_remove_lock); + raw_notifier_chain_unregister(&cpu_chain, nb); + mutex_unlock(&cpu_add_remove_lock); } EXPORT_SYMBOL(unregister_cpu_notifier); -#ifdef CONFIG_HOTPLUG_CPU static inline void check_for_tasks(int cpu) { struct task_struct *p; @@ -122,32 +119,25 @@ static int take_cpu_down(void *unused) return 0; } -int cpu_down(unsigned int cpu) +/* Requires cpu_add_remove_lock to be held */ +static 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) + return -EBUSY; - if (num_online_cpus() == 1) { - err = -EBUSY; - goto out; - } - - if (!cpu_online(cpu)) { - err = -EINVAL; - goto out; - } + if (!cpu_online(cpu)) + return -EINVAL; - err = notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE, + err = raw_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; + return -EINVAL; } /* Ensure that we are not runnable on dying cpu */ @@ -156,19 +146,22 @@ int cpu_down(unsigned int cpu) cpu_clear(cpu, tmp); set_cpus_allowed(current, tmp); + mutex_lock(&cpu_bitmask_lock); p = __stop_machine_run(take_cpu_down, NULL, cpu); - if (IS_ERR(p)) { + mutex_unlock(&cpu_bitmask_lock); + + if (IS_ERR(p) || cpu_online(cpu)) { /* CPU didn't die: tell everyone. Can't complain. */ - if (notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED, + if (raw_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)) + if (IS_ERR(p)) { + err = PTR_ERR(p); + goto out_allowed; + } goto out_thread; + } /* Wait for it to sleep (leaving idle task). */ while (!idle_cpu(cpu)) @@ -182,8 +175,8 @@ int cpu_down(unsigned int 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 (raw_notifier_call_chain(&cpu_chain, CPU_DEAD, + (void *)(long)cpu) == NOTIFY_BAD) BUG(); check_for_tasks(cpu); @@ -192,26 +185,34 @@ out_thread: err = kthread_stop(p); out_allowed: set_cpus_allowed(current, old_allowed); -out: - unlock_cpu_hotplug(); + return err; +} + +int cpu_down(unsigned int cpu) +{ + int err = 0; + + mutex_lock(&cpu_add_remove_lock); + if (cpu_hotplug_disabled) + err = -EBUSY; + else + err = _cpu_down(cpu); + + mutex_unlock(&cpu_add_remove_lock); return err; } #endif /*CONFIG_HOTPLUG_CPU*/ -int __devinit cpu_up(unsigned int cpu) +/* Requires cpu_add_remove_lock to be held */ +static int __cpuinit _cpu_up(unsigned int cpu) { int ret; void *hcpu = (void *)(long)cpu; - if ((ret = lock_cpu_hotplug_interruptible()) != 0) - return ret; + if (cpu_online(cpu) || !cpu_present(cpu)) + return -EINVAL; - if (cpu_online(cpu) || !cpu_present(cpu)) { - ret = -EINVAL; - goto out; - } - - ret = notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu); + ret = raw_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); @@ -220,19 +221,105 @@ int __devinit cpu_up(unsigned int cpu) } /* Arch-specific enabling code. */ + mutex_lock(&cpu_bitmask_lock); ret = __cpu_up(cpu); + mutex_unlock(&cpu_bitmask_lock); 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); + raw_notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu); out_notify: if (ret != 0) - notifier_call_chain(&cpu_chain, CPU_UP_CANCELED, hcpu); -out: - unlock_cpu_hotplug(); + raw_notifier_call_chain(&cpu_chain, + CPU_UP_CANCELED, hcpu); + return ret; } + +int __cpuinit cpu_up(unsigned int cpu) +{ + int err = 0; + + mutex_lock(&cpu_add_remove_lock); + if (cpu_hotplug_disabled) + err = -EBUSY; + else + err = _cpu_up(cpu); + + mutex_unlock(&cpu_add_remove_lock); + return err; +} + +#ifdef CONFIG_SUSPEND_SMP +static cpumask_t frozen_cpus; + +int disable_nonboot_cpus(void) +{ + int cpu, first_cpu, error = 0; + + mutex_lock(&cpu_add_remove_lock); + first_cpu = first_cpu(cpu_present_map); + if (!cpu_online(first_cpu)) { + error = _cpu_up(first_cpu); + if (error) { + printk(KERN_ERR "Could not bring CPU%d up.\n", + first_cpu); + goto out; + } + } + + /* We take down all of the non-boot CPUs in one shot to avoid races + * with the userspace trying to use the CPU hotplug at the same time + */ + cpus_clear(frozen_cpus); + printk("Disabling non-boot CPUs ...\n"); + for_each_online_cpu(cpu) { + if (cpu == first_cpu) + continue; + error = _cpu_down(cpu); + if (!error) { + cpu_set(cpu, frozen_cpus); + printk("CPU%d is down\n", cpu); + } else { + printk(KERN_ERR "Error taking CPU%d down: %d\n", + cpu, error); + break; + } + } + if (!error) { + BUG_ON(num_online_cpus() > 1); + /* Make sure the CPUs won't be enabled by someone else */ + cpu_hotplug_disabled = 1; + } else { + printk(KERN_ERR "Non-boot CPUs are not disabled\n"); + } +out: + mutex_unlock(&cpu_add_remove_lock); + return error; +} + +void enable_nonboot_cpus(void) +{ + int cpu, error; + + /* Allow everyone to use the CPU hotplug again */ + mutex_lock(&cpu_add_remove_lock); + cpu_hotplug_disabled = 0; + mutex_unlock(&cpu_add_remove_lock); + + printk("Enabling non-boot CPUs ...\n"); + for_each_cpu_mask(cpu, frozen_cpus) { + error = cpu_up(cpu); + if (!error) { + printk("CPU%d is up\n", cpu); + continue; + } + printk(KERN_WARNING "Error taking CPU%d up: %d\n", + cpu, error); + } + cpus_clear(frozen_cpus); +} +#endif