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- /* CPU control.
- * (C) 2001, 2002, 2003, 2004 Rusty Russell
- *
- * This code is licenced under the GPL.
- */
- #include <linux/proc_fs.h>
- #include <linux/smp.h>
- #include <linux/init.h>
- #include <linux/notifier.h>
- #include <linux/sched.h>
- #include <linux/unistd.h>
- #include <linux/cpu.h>
- #include <linux/module.h>
- #include <linux/kthread.h>
- #include <linux/stop_machine.h>
- #include <linux/mutex.h>
- /*
- * 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.
- */
- cpumask_t cpu_present_map __read_mostly;
- EXPORT_SYMBOL(cpu_present_map);
- #ifndef CONFIG_SMP
- /*
- * Represents all cpu's that are currently online.
- */
- cpumask_t cpu_online_map __read_mostly = CPU_MASK_ALL;
- EXPORT_SYMBOL(cpu_online_map);
- cpumask_t cpu_possible_map __read_mostly = CPU_MASK_ALL;
- EXPORT_SYMBOL(cpu_possible_map);
- #else /* CONFIG_SMP */
- /* Serializes the updates to cpu_online_map, cpu_present_map */
- static DEFINE_MUTEX(cpu_add_remove_lock);
- static __cpuinitdata RAW_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;
- static struct {
- struct task_struct *active_writer;
- struct mutex lock; /* Synchronizes accesses to refcount, */
- /*
- * Also blocks the new readers during
- * an ongoing cpu hotplug operation.
- */
- int refcount;
- } cpu_hotplug;
- void __init cpu_hotplug_init(void)
- {
- cpu_hotplug.active_writer = NULL;
- mutex_init(&cpu_hotplug.lock);
- cpu_hotplug.refcount = 0;
- }
- cpumask_t cpu_active_map;
- #ifdef CONFIG_HOTPLUG_CPU
- void get_online_cpus(void)
- {
- might_sleep();
- if (cpu_hotplug.active_writer == current)
- return;
- mutex_lock(&cpu_hotplug.lock);
- cpu_hotplug.refcount++;
- mutex_unlock(&cpu_hotplug.lock);
- }
- EXPORT_SYMBOL_GPL(get_online_cpus);
- void put_online_cpus(void)
- {
- if (cpu_hotplug.active_writer == current)
- return;
- mutex_lock(&cpu_hotplug.lock);
- if (!--cpu_hotplug.refcount && unlikely(cpu_hotplug.active_writer))
- wake_up_process(cpu_hotplug.active_writer);
- mutex_unlock(&cpu_hotplug.lock);
- }
- EXPORT_SYMBOL_GPL(put_online_cpus);
- #endif /* CONFIG_HOTPLUG_CPU */
- /*
- * The following two API's must be used when attempting
- * to serialize the updates to cpu_online_map, cpu_present_map.
- */
- void cpu_maps_update_begin(void)
- {
- mutex_lock(&cpu_add_remove_lock);
- }
- void cpu_maps_update_done(void)
- {
- mutex_unlock(&cpu_add_remove_lock);
- }
- /*
- * This ensures that the hotplug operation can begin only when the
- * refcount goes to zero.
- *
- * Note that during a cpu-hotplug operation, the new readers, if any,
- * will be blocked by the cpu_hotplug.lock
- *
- * 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
- * writer.
- * - Last reader unlocks the cpu_hotplug.lock.
- * - A new reader arrives at this moment, bumps up the refcount.
- * - The writer acquires the cpu_hotplug.lock finds the refcount
- * non zero and goes to sleep again.
- *
- * However, this is very difficult to achieve in practice since
- * get_online_cpus() not an api which is called all that often.
- *
- */
- static void cpu_hotplug_begin(void)
- {
- cpu_hotplug.active_writer = current;
- for (;;) {
- mutex_lock(&cpu_hotplug.lock);
- if (likely(!cpu_hotplug.refcount))
- break;
- __set_current_state(TASK_UNINTERRUPTIBLE);
- mutex_unlock(&cpu_hotplug.lock);
- schedule();
- }
- }
- static void cpu_hotplug_done(void)
- {
- cpu_hotplug.active_writer = NULL;
- mutex_unlock(&cpu_hotplug.lock);
- }
- /* Need to know about CPUs going up/down? */
- int __ref register_cpu_notifier(struct notifier_block *nb)
- {
- int ret;
- cpu_maps_update_begin();
- ret = raw_notifier_chain_register(&cpu_chain, nb);
- cpu_maps_update_done();
- return ret;
- }
- #ifdef CONFIG_HOTPLUG_CPU
- EXPORT_SYMBOL(register_cpu_notifier);
- void __ref unregister_cpu_notifier(struct notifier_block *nb)
- {
- cpu_maps_update_begin();
- raw_notifier_chain_unregister(&cpu_chain, nb);
- cpu_maps_update_done();
- }
- EXPORT_SYMBOL(unregister_cpu_notifier);
- 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 &&
- (!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 = %x) \n",
- p->comm, task_pid_nr(p), cpu,
- p->state, p->flags);
- }
- write_unlock_irq(&tasklist_lock);
- }
- struct take_cpu_down_param {
- unsigned long mod;
- void *hcpu;
- };
- /* Take this CPU down. */
- static int __ref take_cpu_down(void *_param)
- {
- struct take_cpu_down_param *param = _param;
- int err;
- raw_notifier_call_chain(&cpu_chain, CPU_DYING | param->mod,
- param->hcpu);
- /* Ensure this CPU doesn't handle any more interrupts. */
- err = __cpu_disable();
- if (err < 0)
- 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;
- }
- /* Requires cpu_add_remove_lock to be held */
- static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
- {
- int err, nr_calls = 0;
- struct task_struct *p;
- cpumask_t old_allowed, tmp;
- void *hcpu = (void *)(long)cpu;
- unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
- struct take_cpu_down_param tcd_param = {
- .mod = mod,
- .hcpu = hcpu,
- };
- if (num_online_cpus() == 1)
- return -EBUSY;
- if (!cpu_online(cpu))
- return -EINVAL;
- cpu_hotplug_begin();
- err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE | mod,
- hcpu, -1, &nr_calls);
- if (err == NOTIFY_BAD) {
- nr_calls--;
- __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
- hcpu, nr_calls, NULL);
- printk("%s: attempt to take down CPU %u failed\n",
- __func__, cpu);
- err = -EINVAL;
- goto out_release;
- }
- /* Ensure that we are not runnable on dying cpu */
- old_allowed = current->cpus_allowed;
- cpus_setall(tmp);
- cpu_clear(cpu, tmp);
- set_cpus_allowed_ptr(current, &tmp);
- p = __stop_machine_run(take_cpu_down, &tcd_param, cpu);
- if (IS_ERR(p) || cpu_online(cpu)) {
- /* CPU didn't die: tell everyone. Can't complain. */
- if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
- hcpu) == NOTIFY_BAD)
- BUG();
- 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))
- yield();
- /* This actually kills the CPU. */
- __cpu_die(cpu);
- /* CPU is completely dead: tell everyone. Too late to complain. */
- if (raw_notifier_call_chain(&cpu_chain, CPU_DEAD | mod,
- hcpu) == NOTIFY_BAD)
- BUG();
- check_for_tasks(cpu);
- out_thread:
- err = kthread_stop(p);
- out_allowed:
- set_cpus_allowed_ptr(current, &old_allowed);
- out_release:
- cpu_hotplug_done();
- if (!err) {
- if (raw_notifier_call_chain(&cpu_chain, CPU_POST_DEAD | mod,
- hcpu) == NOTIFY_BAD)
- BUG();
- }
- return err;
- }
- int __ref cpu_down(unsigned int cpu)
- {
- int err = 0;
- cpu_maps_update_begin();
- if (cpu_hotplug_disabled) {
- err = -EBUSY;
- goto out;
- }
- cpu_clear(cpu, cpu_active_map);
- /*
- * Make sure the all cpus did the reschedule and are not
- * using stale version of the cpu_active_map.
- * This is not strictly necessary becuase stop_machine()
- * that we run down the line already provides the required
- * synchronization. But it's really a side effect and we do not
- * want to depend on the innards of the stop_machine here.
- */
- synchronize_sched();
- err = _cpu_down(cpu, 0);
- if (cpu_online(cpu))
- cpu_set(cpu, cpu_active_map);
- out:
- cpu_maps_update_done();
- return err;
- }
- EXPORT_SYMBOL(cpu_down);
- #endif /*CONFIG_HOTPLUG_CPU*/
- /* Requires cpu_add_remove_lock to be held */
- static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
- {
- int ret, nr_calls = 0;
- void *hcpu = (void *)(long)cpu;
- unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
- if (cpu_online(cpu) || !cpu_present(cpu))
- return -EINVAL;
- cpu_hotplug_begin();
- ret = __raw_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE | mod, hcpu,
- -1, &nr_calls);
- if (ret == NOTIFY_BAD) {
- nr_calls--;
- printk("%s: attempt to bring up CPU %u failed\n",
- __func__, cpu);
- ret = -EINVAL;
- goto out_notify;
- }
- /* Arch-specific enabling code. */
- ret = __cpu_up(cpu);
- if (ret != 0)
- goto out_notify;
- BUG_ON(!cpu_online(cpu));
- /* Now call notifier in preparation. */
- raw_notifier_call_chain(&cpu_chain, CPU_ONLINE | mod, hcpu);
- out_notify:
- if (ret != 0)
- __raw_notifier_call_chain(&cpu_chain,
- CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
- cpu_hotplug_done();
- return ret;
- }
- int __cpuinit cpu_up(unsigned int cpu)
- {
- int err = 0;
- if (!cpu_isset(cpu, cpu_possible_map)) {
- printk(KERN_ERR "can't online cpu %d because it is not "
- "configured as may-hotadd at boot time\n", cpu);
- #if defined(CONFIG_IA64) || defined(CONFIG_X86_64) || defined(CONFIG_S390)
- printk(KERN_ERR "please check additional_cpus= boot "
- "parameter\n");
- #endif
- return -EINVAL;
- }
- cpu_maps_update_begin();
- if (cpu_hotplug_disabled) {
- err = -EBUSY;
- goto out;
- }
- err = _cpu_up(cpu, 0);
- if (cpu_online(cpu))
- cpu_set(cpu, cpu_active_map);
- out:
- cpu_maps_update_done();
- return err;
- }
- #ifdef CONFIG_PM_SLEEP_SMP
- static cpumask_t frozen_cpus;
- int disable_nonboot_cpus(void)
- {
- int cpu, first_cpu, error = 0;
- cpu_maps_update_begin();
- first_cpu = first_cpu(cpu_online_map);
- /* 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, 1);
- 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");
- }
- cpu_maps_update_done();
- return error;
- }
- void __ref enable_nonboot_cpus(void)
- {
- int cpu, error;
- /* Allow everyone to use the CPU hotplug again */
- cpu_maps_update_begin();
- cpu_hotplug_disabled = 0;
- if (cpus_empty(frozen_cpus))
- goto out;
- printk("Enabling non-boot CPUs ...\n");
- for_each_cpu_mask_nr(cpu, frozen_cpus) {
- error = _cpu_up(cpu, 1);
- 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);
- out:
- cpu_maps_update_done();
- }
- #endif /* CONFIG_PM_SLEEP_SMP */
- #endif /* CONFIG_SMP */
- /* 64 bits of zeros, for initializers. */
- #if BITS_PER_LONG == 32
- #define Z64 0, 0
- #else
- #define Z64 0
- #endif
- /* Initializer macros. */
- #define CMI0(n) { .bits = { 1UL << (n) } }
- #define CMI(n, ...) { .bits = { __VA_ARGS__, 1UL << ((n) % BITS_PER_LONG) } }
- #define CMI8(n, ...) \
- CMI((n), __VA_ARGS__), CMI((n)+1, __VA_ARGS__), \
- CMI((n)+2, __VA_ARGS__), CMI((n)+3, __VA_ARGS__), \
- CMI((n)+4, __VA_ARGS__), CMI((n)+5, __VA_ARGS__), \
- CMI((n)+6, __VA_ARGS__), CMI((n)+7, __VA_ARGS__)
- #if BITS_PER_LONG == 32
- #define CMI64(n, ...) \
- CMI8((n), __VA_ARGS__), CMI8((n)+8, __VA_ARGS__), \
- CMI8((n)+16, __VA_ARGS__), CMI8((n)+24, __VA_ARGS__), \
- CMI8((n)+32, 0, __VA_ARGS__), CMI8((n)+40, 0, __VA_ARGS__), \
- CMI8((n)+48, 0, __VA_ARGS__), CMI8((n)+56, 0, __VA_ARGS__)
- #else
- #define CMI64(n, ...) \
- CMI8((n), __VA_ARGS__), CMI8((n)+8, __VA_ARGS__), \
- CMI8((n)+16, __VA_ARGS__), CMI8((n)+24, __VA_ARGS__), \
- CMI8((n)+32, __VA_ARGS__), CMI8((n)+40, __VA_ARGS__), \
- CMI8((n)+48, __VA_ARGS__), CMI8((n)+56, __VA_ARGS__)
- #endif
- #define CMI256(n, ...) \
- CMI64((n), __VA_ARGS__), CMI64((n)+64, Z64, __VA_ARGS__), \
- CMI64((n)+128, Z64, Z64, __VA_ARGS__), \
- CMI64((n)+192, Z64, Z64, Z64, __VA_ARGS__)
- #define Z256 Z64, Z64, Z64, Z64
- #define CMI1024(n, ...) \
- CMI256((n), __VA_ARGS__), \
- CMI256((n)+256, Z256, __VA_ARGS__), \
- CMI256((n)+512, Z256, Z256, __VA_ARGS__), \
- CMI256((n)+768, Z256, Z256, Z256, __VA_ARGS__)
- #define Z1024 Z256, Z256, Z256, Z256
- /* We want this statically initialized, just to be safe. We try not
- * to waste too much space, either. */
- static const cpumask_t cpumask_map[]
- #ifdef CONFIG_HAVE_CPUMASK_OF_CPU_MAP
- __initdata
- #endif
- = {
- CMI0(0), CMI0(1), CMI0(2), CMI0(3),
- #if NR_CPUS > 4
- CMI0(4), CMI0(5), CMI0(6), CMI0(7),
- #endif
- #if NR_CPUS > 8
- CMI0(8), CMI0(9), CMI0(10), CMI0(11),
- CMI0(12), CMI0(13), CMI0(14), CMI0(15),
- #endif
- #if NR_CPUS > 16
- CMI0(16), CMI0(17), CMI0(18), CMI0(19),
- CMI0(20), CMI0(21), CMI0(22), CMI0(23),
- CMI0(24), CMI0(25), CMI0(26), CMI0(27),
- CMI0(28), CMI0(29), CMI0(30), CMI0(31),
- #endif
- #if NR_CPUS > 32
- #if BITS_PER_LONG == 32
- CMI(32, 0), CMI(33, 0), CMI(34, 0), CMI(35, 0),
- CMI(36, 0), CMI(37, 0), CMI(38, 0), CMI(39, 0),
- CMI(40, 0), CMI(41, 0), CMI(42, 0), CMI(43, 0),
- CMI(44, 0), CMI(45, 0), CMI(46, 0), CMI(47, 0),
- CMI(48, 0), CMI(49, 0), CMI(50, 0), CMI(51, 0),
- CMI(52, 0), CMI(53, 0), CMI(54, 0), CMI(55, 0),
- CMI(56, 0), CMI(57, 0), CMI(58, 0), CMI(59, 0),
- CMI(60, 0), CMI(61, 0), CMI(62, 0), CMI(63, 0),
- #else
- CMI0(32), CMI0(33), CMI0(34), CMI0(35),
- CMI0(36), CMI0(37), CMI0(38), CMI0(39),
- CMI0(40), CMI0(41), CMI0(42), CMI0(43),
- CMI0(44), CMI0(45), CMI0(46), CMI0(47),
- CMI0(48), CMI0(49), CMI0(50), CMI0(51),
- CMI0(52), CMI0(53), CMI0(54), CMI0(55),
- CMI0(56), CMI0(57), CMI0(58), CMI0(59),
- CMI0(60), CMI0(61), CMI0(62), CMI0(63),
- #endif /* BITS_PER_LONG == 64 */
- #endif
- #if NR_CPUS > 64
- CMI64(64, Z64),
- #endif
- #if NR_CPUS > 128
- CMI64(128, Z64, Z64), CMI64(192, Z64, Z64, Z64),
- #endif
- #if NR_CPUS > 256
- CMI256(256, Z256),
- #endif
- #if NR_CPUS > 512
- CMI256(512, Z256, Z256), CMI256(768, Z256, Z256, Z256),
- #endif
- #if NR_CPUS > 1024
- CMI1024(1024, Z1024),
- #endif
- #if NR_CPUS > 2048
- CMI1024(2048, Z1024, Z1024), CMI1024(3072, Z1024, Z1024, Z1024),
- #endif
- #if NR_CPUS > 4096
- #error NR_CPUS too big. Fix initializers or set CONFIG_HAVE_CPUMASK_OF_CPU_MAP
- #endif
- };
- const cpumask_t *cpumask_of_cpu_map = cpumask_map;
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