X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=kernel%2Fcpu.c;h=32c96628463eb46bab59ff81928d44e573711170;hb=44f96dd971be982b16be51945bf21e9e1ea4b467;hp=72b984c67eb32ddf78733e56025951eef4a84dc0;hpb=bc77d24c47b89f1e0efed0b8e4be5f8aad102883;p=linux-2.6.git diff --git a/kernel/cpu.c b/kernel/cpu.c index 72b984c67..32c966284 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -11,53 +11,85 @@ #include #include #include -#include /* for hotplug_path */ #include #include -#include +#include /* This protects CPUs going up and down... */ -DECLARE_MUTEX(cpucontrol); - -static struct notifier_block *cpu_chain; -/* - * Represents all cpu's present in the system - * In systems capable of hotplug, this map could dynamically grow - * as new cpu's are detected in the system via any platform specific - * method, such as ACPI for e.g. +static DEFINE_MUTEX(cpu_add_remove_lock); +static DEFINE_MUTEX(cpu_bitmask_lock); + +static __cpuinitdata BLOCKING_NOTIFIER_HEAD(cpu_chain); + +/* If set, cpu_up and cpu_down will return -EBUSY and do nothing. + * Should always be manipulated under cpu_add_remove_lock */ -cpumask_t cpu_present_map; -EXPORT_SYMBOL(cpu_present_map); +static int cpu_hotplug_disabled; -/* Need to know about CPUs going up/down? */ -int register_cpu_notifier(struct notifier_block *nb) +#ifdef CONFIG_HOTPLUG_CPU + +/* Crappy recursive lock-takers in cpufreq! Complain loudly about idiots */ +static struct task_struct *recursive; +static int recursive_depth; + +void lock_cpu_hotplug(void) { - int ret; + 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); - if ((ret = down_interruptible(&cpucontrol)) != 0) - return ret; - ret = notifier_chain_register(&cpu_chain, nb); - up(&cpucontrol); - return ret; +void unlock_cpu_hotplug(void) +{ + WARN_ON(recursive != current); + if (recursive_depth) { + recursive_depth--; + return; + } + mutex_unlock(&cpu_bitmask_lock); + recursive = NULL; +} +EXPORT_SYMBOL_GPL(unlock_cpu_hotplug); + +#endif /* CONFIG_HOTPLUG_CPU */ + +/* Need to know about CPUs going up/down? */ +int __cpuinit register_cpu_notifier(struct notifier_block *nb) +{ + return blocking_notifier_chain_register(&cpu_chain, nb); } + +#ifdef CONFIG_HOTPLUG_CPU + 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 *p; write_lock_irq(&tasklist_lock); for_each_process(p) { - if (task_cpu(p) == cpu && (p->utime != 0 || p->stime != 0)) + 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); @@ -65,70 +97,41 @@ static inline void check_for_tasks(int cpu) 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; - 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) +/* 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)) + return -EINVAL; - if (!cpu_online(cpu)) { - err = -EINVAL; - 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); + return -EINVAL; } /* Ensure that we are not runnable on dying cpu */ @@ -137,8 +140,16 @@ 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); + mutex_unlock(&cpu_bitmask_lock); + 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_allowed; } @@ -154,45 +165,48 @@ 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(); 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) + +int cpu_down(unsigned int cpu) { - return 0; + 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 __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)) + return -EINVAL; - 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); @@ -201,19 +215,109 @@ 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); + blocking_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); + blocking_notifier_call_chain(&cpu_chain, + CPU_UP_CANCELED, hcpu); + return ret; } + +int __devinit 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; + + 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; + } + } + error = set_cpus_allowed(current, cpumask_of_cpu(first_cpu)); + if (error) { + printk(KERN_ERR "Could not run on CPU%d\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"); + } +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