diff options
Diffstat (limited to 'kernel/cpu.c')
| -rw-r--r-- | kernel/cpu.c | 44 |
1 files changed, 17 insertions, 27 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index 2011ad8d2697..c77bc3a1c722 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -33,17 +33,13 @@ static struct { * an ongoing cpu hotplug operation. */ int refcount; - wait_queue_head_t writer_queue; } cpu_hotplug; -#define writer_exists() (cpu_hotplug.active_writer != NULL) - void __init cpu_hotplug_init(void) { cpu_hotplug.active_writer = NULL; mutex_init(&cpu_hotplug.lock); cpu_hotplug.refcount = 0; - init_waitqueue_head(&cpu_hotplug.writer_queue); } #ifdef CONFIG_HOTPLUG_CPU @@ -65,11 +61,8 @@ void put_online_cpus(void) if (cpu_hotplug.active_writer == current) return; mutex_lock(&cpu_hotplug.lock); - cpu_hotplug.refcount--; - - if (unlikely(writer_exists()) && !cpu_hotplug.refcount) - wake_up(&cpu_hotplug.writer_queue); - + if (!--cpu_hotplug.refcount && unlikely(cpu_hotplug.active_writer)) + wake_up_process(cpu_hotplug.active_writer); mutex_unlock(&cpu_hotplug.lock); } @@ -98,8 +91,8 @@ void cpu_maps_update_done(void) * Note that during a cpu-hotplug operation, the new readers, if any, * will be blocked by the cpu_hotplug.lock * - * Since cpu_maps_update_begin is always called after invoking - * cpu_maps_update_begin, we can be sure that only one writer is active. + * Since cpu_hotplug_begin() is always called after invoking + * cpu_maps_update_begin(), we can be sure that only one writer is active. * * Note that theoretically, there is a possibility of a livelock: * - Refcount goes to zero, last reader wakes up the sleeping @@ -115,19 +108,16 @@ void cpu_maps_update_done(void) */ static void cpu_hotplug_begin(void) { - DECLARE_WAITQUEUE(wait, current); - - mutex_lock(&cpu_hotplug.lock); - cpu_hotplug.active_writer = current; - add_wait_queue_exclusive(&cpu_hotplug.writer_queue, &wait); - while (cpu_hotplug.refcount) { - set_current_state(TASK_UNINTERRUPTIBLE); + + for (;;) { + mutex_lock(&cpu_hotplug.lock); + if (likely(!cpu_hotplug.refcount)) + break; + __set_current_state(TASK_UNINTERRUPTIBLE); mutex_unlock(&cpu_hotplug.lock); schedule(); - mutex_lock(&cpu_hotplug.lock); } - remove_wait_queue_locked(&cpu_hotplug.writer_queue, &wait); } static void cpu_hotplug_done(void) @@ -136,7 +126,7 @@ static void cpu_hotplug_done(void) mutex_unlock(&cpu_hotplug.lock); } /* Need to know about CPUs going up/down? */ -int __cpuinit register_cpu_notifier(struct notifier_block *nb) +int __ref register_cpu_notifier(struct notifier_block *nb) { int ret; cpu_maps_update_begin(); @@ -149,7 +139,7 @@ int __cpuinit register_cpu_notifier(struct notifier_block *nb) EXPORT_SYMBOL(register_cpu_notifier); -void unregister_cpu_notifier(struct notifier_block *nb) +void __ref unregister_cpu_notifier(struct notifier_block *nb) { cpu_maps_update_begin(); raw_notifier_chain_unregister(&cpu_chain, nb); @@ -180,7 +170,7 @@ struct take_cpu_down_param { }; /* Take this CPU down. */ -static int take_cpu_down(void *_param) +static int __ref take_cpu_down(void *_param) { struct take_cpu_down_param *param = _param; int err; @@ -199,7 +189,7 @@ static int take_cpu_down(void *_param) } /* Requires cpu_add_remove_lock to be held */ -static int _cpu_down(unsigned int cpu, int tasks_frozen) +static int __ref _cpu_down(unsigned int cpu, int tasks_frozen) { int err, nr_calls = 0; struct task_struct *p; @@ -225,7 +215,7 @@ static int _cpu_down(unsigned int cpu, int tasks_frozen) __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod, hcpu, nr_calls, NULL); printk("%s: attempt to take down CPU %u failed\n", - __FUNCTION__, cpu); + __func__, cpu); err = -EINVAL; goto out_release; } @@ -274,7 +264,7 @@ out_release: return err; } -int cpu_down(unsigned int cpu) +int __ref cpu_down(unsigned int cpu) { int err = 0; @@ -305,7 +295,7 @@ static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen) if (ret == NOTIFY_BAD) { nr_calls--; printk("%s: attempt to bring up CPU %u failed\n", - __FUNCTION__, cpu); + __func__, cpu); ret = -EINVAL; goto out_notify; } |