diff options
Diffstat (limited to 'kernel/cpu.c')
| -rw-r--r-- | kernel/cpu.c | 138 |
1 files changed, 118 insertions, 20 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index f230f9a..32c9662 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -21,6 +21,11 @@ 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 + */ +static int cpu_hotplug_disabled; + #ifdef CONFIG_HOTPLUG_CPU /* Crappy recursive lock-takers in cpufreq! Complain loudly about idiots */ @@ -108,30 +113,25 @@ 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; - mutex_lock(&cpu_add_remove_lock); - if (num_online_cpus() == 1) { - err = -EBUSY; - goto out; - } + if (num_online_cpus() == 1) + return -EBUSY; - if (!cpu_online(cpu)) { - err = -EINVAL; - goto out; - } + if (!cpu_online(cpu)) + return -EINVAL; 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; + return -EINVAL; } /* Ensure that we are not runnable on dying cpu */ @@ -179,22 +179,32 @@ out_thread: err = kthread_stop(p); out_allowed: set_cpus_allowed(current, old_allowed); -out: + 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 __devinit _cpu_up(unsigned int cpu) { int ret; void *hcpu = (void *)(long)cpu; - mutex_lock(&cpu_add_remove_lock); - if (cpu_online(cpu) || !cpu_present(cpu)) { - ret = -EINVAL; - goto out; - } + if (cpu_online(cpu) || !cpu_present(cpu)) + return -EINVAL; ret = blocking_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu); if (ret == NOTIFY_BAD) { @@ -219,7 +229,95 @@ out_notify: if (ret != 0) 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 ret; + 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 |