/* CPU control. * (C) 2001, 2002, 2003, 2004 Rusty Russell * * This code is licenced under the GPL. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define CREATE_TRACE_POINTS #include #include "smpboot.h" /** * cpuhp_cpu_state - Per cpu hotplug state storage * @state: The current cpu state * @target: The target state */ struct cpuhp_cpu_state { enum cpuhp_state state; enum cpuhp_state target; }; static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state); /** * cpuhp_step - Hotplug state machine step * @name: Name of the step * @startup: Startup function of the step * @teardown: Teardown function of the step * @skip_onerr: Do not invoke the functions on error rollback * Will go away once the notifiers are gone */ struct cpuhp_step { const char *name; int (*startup)(unsigned int cpu); int (*teardown)(unsigned int cpu); bool skip_onerr; }; static struct cpuhp_step cpuhp_bp_states[]; /** * cpuhp_invoke_callback _ Invoke the callbacks for a given state * @cpu: The cpu for which the callback should be invoked * @step: The step in the state machine * @cb: The callback function to invoke * * Called from cpu hotplug and from the state register machinery */ static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state step, int (*cb)(unsigned int)) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); int ret = 0; if (cb) { trace_cpuhp_enter(cpu, st->target, step, cb); ret = cb(cpu); trace_cpuhp_exit(cpu, st->state, step, ret); } return ret; } #ifdef CONFIG_SMP /* Serializes the updates to cpu_online_mask, cpu_present_mask */ static DEFINE_MUTEX(cpu_add_remove_lock); bool cpuhp_tasks_frozen; EXPORT_SYMBOL_GPL(cpuhp_tasks_frozen); /* * The following two APIs (cpu_maps_update_begin/done) must be used when * attempting to serialize the updates to cpu_online_mask & cpu_present_mask. * The APIs cpu_notifier_register_begin/done() must be used to protect CPU * hotplug callback (un)registration performed using __register_cpu_notifier() * or __unregister_cpu_notifier(). */ void cpu_maps_update_begin(void) { mutex_lock(&cpu_add_remove_lock); } EXPORT_SYMBOL(cpu_notifier_register_begin); void cpu_maps_update_done(void) { mutex_unlock(&cpu_add_remove_lock); } EXPORT_SYMBOL(cpu_notifier_register_done); static 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; #ifdef CONFIG_HOTPLUG_CPU static struct { struct task_struct *active_writer; /* wait queue to wake up the active_writer */ wait_queue_head_t wq; /* verifies that no writer will get active while readers are active */ struct mutex lock; /* * Also blocks the new readers during * an ongoing cpu hotplug operation. */ atomic_t refcount; #ifdef CONFIG_DEBUG_LOCK_ALLOC struct lockdep_map dep_map; #endif } cpu_hotplug = { .active_writer = NULL, .wq = __WAIT_QUEUE_HEAD_INITIALIZER(cpu_hotplug.wq), .lock = __MUTEX_INITIALIZER(cpu_hotplug.lock), #ifdef CONFIG_DEBUG_LOCK_ALLOC .dep_map = {.name = "cpu_hotplug.lock" }, #endif }; /* Lockdep annotations for get/put_online_cpus() and cpu_hotplug_begin/end() */ #define cpuhp_lock_acquire_read() lock_map_acquire_read(&cpu_hotplug.dep_map) #define cpuhp_lock_acquire_tryread() \ lock_map_acquire_tryread(&cpu_hotplug.dep_map) #define cpuhp_lock_acquire() lock_map_acquire(&cpu_hotplug.dep_map) #define cpuhp_lock_release() lock_map_release(&cpu_hotplug.dep_map) void get_online_cpus(void) { might_sleep(); if (cpu_hotplug.active_writer == current) return; cpuhp_lock_acquire_read(); mutex_lock(&cpu_hotplug.lock); atomic_inc(&cpu_hotplug.refcount); mutex_unlock(&cpu_hotplug.lock); } EXPORT_SYMBOL_GPL(get_online_cpus); void put_online_cpus(void) { int refcount; if (cpu_hotplug.active_writer == current) return; refcount = atomic_dec_return(&cpu_hotplug.refcount); if (WARN_ON(refcount < 0)) /* try to fix things up */ atomic_inc(&cpu_hotplug.refcount); if (refcount <= 0 && waitqueue_active(&cpu_hotplug.wq)) wake_up(&cpu_hotplug.wq); cpuhp_lock_release(); } EXPORT_SYMBOL_GPL(put_online_cpus); /* * 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. * */ void cpu_hotplug_begin(void) { DEFINE_WAIT(wait); cpu_hotplug.active_writer = current; cpuhp_lock_acquire(); for (;;) { mutex_lock(&cpu_hotplug.lock); prepare_to_wait(&cpu_hotplug.wq, &wait, TASK_UNINTERRUPTIBLE); if (likely(!atomic_read(&cpu_hotplug.refcount))) break; mutex_unlock(&cpu_hotplug.lock); schedule(); } finish_wait(&cpu_hotplug.wq, &wait); } void cpu_hotplug_done(void) { cpu_hotplug.active_writer = NULL; mutex_unlock(&cpu_hotplug.lock); cpuhp_lock_release(); } /* * Wait for currently running CPU hotplug operations to complete (if any) and * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the * hotplug path before performing hotplug operations. So acquiring that lock * guarantees mutual exclusion from any currently running hotplug operations. */ void cpu_hotplug_disable(void) { cpu_maps_update_begin(); cpu_hotplug_disabled++; cpu_maps_update_done(); } EXPORT_SYMBOL_GPL(cpu_hotplug_disable); void cpu_hotplug_enable(void) { cpu_maps_update_begin(); WARN_ON(--cpu_hotplug_disabled < 0); cpu_maps_update_done(); } EXPORT_SYMBOL_GPL(cpu_hotplug_enable); #endif /* CONFIG_HOTPLUG_CPU */ /* Need to know about CPUs going up/down? */ int 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; } int __register_cpu_notifier(struct notifier_block *nb) { return raw_notifier_chain_register(&cpu_chain, nb); } static int __cpu_notify(unsigned long val, unsigned int cpu, int nr_to_call, int *nr_calls) { unsigned long mod = cpuhp_tasks_frozen ? CPU_TASKS_FROZEN : 0; void *hcpu = (void *)(long)cpu; int ret; ret = __raw_notifier_call_chain(&cpu_chain, val | mod, hcpu, nr_to_call, nr_calls); return notifier_to_errno(ret); } static int cpu_notify(unsigned long val, unsigned int cpu) { return __cpu_notify(val, cpu, -1, NULL); } /* Notifier wrappers for transitioning to state machine */ static int notify_prepare(unsigned int cpu) { int nr_calls = 0; int ret; ret = __cpu_notify(CPU_UP_PREPARE, cpu, -1, &nr_calls); if (ret) { nr_calls--; printk(KERN_WARNING "%s: attempt to bring up CPU %u failed\n", __func__, cpu); __cpu_notify(CPU_UP_CANCELED, cpu, nr_calls, NULL); } return ret; } static int notify_online(unsigned int cpu) { cpu_notify(CPU_ONLINE, cpu); return 0; } static int bringup_cpu(unsigned int cpu) { struct task_struct *idle = idle_thread_get(cpu); int ret; /* Arch-specific enabling code. */ ret = __cpu_up(cpu, idle); if (ret) { cpu_notify(CPU_UP_CANCELED, cpu); return ret; } BUG_ON(!cpu_online(cpu)); return 0; } #ifdef CONFIG_HOTPLUG_CPU EXPORT_SYMBOL(register_cpu_notifier); EXPORT_SYMBOL(__register_cpu_notifier); void 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); void __unregister_cpu_notifier(struct notifier_block *nb) { raw_notifier_chain_unregister(&cpu_chain, nb); } EXPORT_SYMBOL(__unregister_cpu_notifier); /** * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU * @cpu: a CPU id * * This function walks all processes, finds a valid mm struct for each one and * then clears a corresponding bit in mm's cpumask. While this all sounds * trivial, there are various non-obvious corner cases, which this function * tries to solve in a safe manner. * * Also note that the function uses a somewhat relaxed locking scheme, so it may * be called only for an already offlined CPU. */ void clear_tasks_mm_cpumask(int cpu) { struct task_struct *p; /* * This function is called after the cpu is taken down and marked * offline, so its not like new tasks will ever get this cpu set in * their mm mask. -- Peter Zijlstra * Thus, we may use rcu_read_lock() here, instead of grabbing * full-fledged tasklist_lock. */ WARN_ON(cpu_online(cpu)); rcu_read_lock(); for_each_process(p) { struct task_struct *t; /* * Main thread might exit, but other threads may still have * a valid mm. Find one. */ t = find_lock_task_mm(p); if (!t) continue; cpumask_clear_cpu(cpu, mm_cpumask(t->mm)); task_unlock(t); } rcu_read_unlock(); } static inline void check_for_tasks(int dead_cpu) { struct task_struct *g, *p; read_lock(&tasklist_lock); for_each_process_thread(g, p) { if (!p->on_rq) continue; /* * We do the check with unlocked task_rq(p)->lock. * Order the reading to do not warn about a task, * which was running on this cpu in the past, and * it's just been woken on another cpu. */ rmb(); if (task_cpu(p) != dead_cpu) continue; pr_warn("Task %s (pid=%d) is on cpu %d (state=%ld, flags=%x)\n", p->comm, task_pid_nr(p), dead_cpu, p->state, p->flags); } read_unlock(&tasklist_lock); } static void cpu_notify_nofail(unsigned long val, unsigned int cpu) { BUG_ON(cpu_notify(val, cpu)); } static int notify_down_prepare(unsigned int cpu) { int err, nr_calls = 0; err = __cpu_notify(CPU_DOWN_PREPARE, cpu, -1, &nr_calls); if (err) { nr_calls--; __cpu_notify(CPU_DOWN_FAILED, cpu, nr_calls, NULL); pr_warn("%s: attempt to take down CPU %u failed\n", __func__, cpu); } return err; } /* Take this CPU down. */ static int take_cpu_down(void *_param) { int err, cpu = smp_processor_id(); /* Ensure this CPU doesn't handle any more interrupts. */ err = __cpu_disable(); if (err < 0) return err; cpu_notify(CPU_DYING, cpu); /* Give up timekeeping duties */ tick_handover_do_timer(); /* Park the stopper thread */ stop_machine_park(cpu); return 0; } static int takedown_cpu(unsigned int cpu) { int err; /* * By now we've cleared cpu_active_mask, wait for all preempt-disabled * and RCU users of this state to go away such that all new such users * will observe it. * * For CONFIG_PREEMPT we have preemptible RCU and its sync_rcu() might * not imply sync_sched(), so wait for both. * * Do sync before park smpboot threads to take care the rcu boost case. */ if (IS_ENABLED(CONFIG_PREEMPT)) synchronize_rcu_mult(call_rcu, call_rcu_sched); else synchronize_rcu(); smpboot_park_threads(cpu); /* * Prevent irq alloc/free while the dying cpu reorganizes the * interrupt affinities. */ irq_lock_sparse(); /* * So now all preempt/rcu users must observe !cpu_active(). */ err = stop_machine(take_cpu_down, NULL, cpumask_of(cpu)); if (err) { /* CPU didn't die: tell everyone. Can't complain. */ cpu_notify_nofail(CPU_DOWN_FAILED, cpu); irq_unlock_sparse(); return err; } BUG_ON(cpu_online(cpu)); /* * The migration_call() CPU_DYING callback will have removed all * runnable tasks from the cpu, there's only the idle task left now * that the migration thread is done doing the stop_machine thing. * * Wait for the stop thread to go away. */ while (!per_cpu(cpu_dead_idle, cpu)) cpu_relax(); smp_mb(); /* Read from cpu_dead_idle before __cpu_die(). */ per_cpu(cpu_dead_idle, cpu) = false; /* Interrupts are moved away from the dying cpu, reenable alloc/free */ irq_unlock_sparse(); hotplug_cpu__broadcast_tick_pull(cpu); /* This actually kills the CPU. */ __cpu_die(cpu); tick_cleanup_dead_cpu(cpu); return 0; } static int notify_dead(unsigned int cpu) { cpu_notify_nofail(CPU_DEAD, cpu); check_for_tasks(cpu); return 0; } #else #define notify_down_prepare NULL #define takedown_cpu NULL #define notify_dead NULL #endif #ifdef CONFIG_HOTPLUG_CPU static void undo_cpu_down(unsigned int cpu, struct cpuhp_cpu_state *st) { for (st->state++; st->state < st->target; st->state++) { struct cpuhp_step *step = cpuhp_bp_states + st->state; if (!step->skip_onerr) cpuhp_invoke_callback(cpu, st->state, step->startup); } } /* Requires cpu_add_remove_lock to be held */ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); int prev_state, ret = 0; bool hasdied = false; if (num_online_cpus() == 1) return -EBUSY; if (!cpu_online(cpu)) return -EINVAL; cpu_hotplug_begin(); cpuhp_tasks_frozen = tasks_frozen; prev_state = st->state; st->target = CPUHP_OFFLINE; for (; st->state > st->target; st->state--) { struct cpuhp_step *step = cpuhp_bp_states + st->state; ret = cpuhp_invoke_callback(cpu, st->state, step->teardown); if (ret) { st->target = prev_state; undo_cpu_down(cpu, st); break; } } hasdied = prev_state != st->state && st->state == CPUHP_OFFLINE; cpu_hotplug_done(); /* This post dead nonsense must die */ if (!ret && hasdied) cpu_notify_nofail(CPU_POST_DEAD, cpu); return ret; } int cpu_down(unsigned int cpu) { int err; cpu_maps_update_begin(); if (cpu_hotplug_disabled) { err = -EBUSY; goto out; } err = _cpu_down(cpu, 0); out: cpu_maps_update_done(); return err; } EXPORT_SYMBOL(cpu_down); #endif /*CONFIG_HOTPLUG_CPU*/ /* * Unpark per-CPU smpboot kthreads at CPU-online time. */ static int smpboot_thread_call(struct notifier_block *nfb, unsigned long action, void *hcpu) { int cpu = (long)hcpu; switch (action & ~CPU_TASKS_FROZEN) { case CPU_DOWN_FAILED: case CPU_ONLINE: smpboot_unpark_threads(cpu); break; default: break; } return NOTIFY_OK; } static struct notifier_block smpboot_thread_notifier = { .notifier_call = smpboot_thread_call, .priority = CPU_PRI_SMPBOOT, }; void smpboot_thread_init(void) { register_cpu_notifier(&smpboot_thread_notifier); } static void undo_cpu_up(unsigned int cpu, struct cpuhp_cpu_state *st) { for (st->state--; st->state > st->target; st->state--) { struct cpuhp_step *step = cpuhp_bp_states + st->state; if (!step->skip_onerr) cpuhp_invoke_callback(cpu, st->state, step->teardown); } } /* Requires cpu_add_remove_lock to be held */ static int _cpu_up(unsigned int cpu, int tasks_frozen) { struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); struct task_struct *idle; int prev_state, ret = 0; cpu_hotplug_begin(); if (cpu_online(cpu) || !cpu_present(cpu)) { ret = -EINVAL; goto out; } /* Let it fail before we try to bring the cpu up */ idle = idle_thread_get(cpu); if (IS_ERR(idle)) { ret = PTR_ERR(idle); goto out; } cpuhp_tasks_frozen = tasks_frozen; prev_state = st->state; st->target = CPUHP_ONLINE; while (st->state < st->target) { struct cpuhp_step *step; st->state++; step = cpuhp_bp_states + st->state; ret = cpuhp_invoke_callback(cpu, st->state, step->startup); if (ret) { st->target = prev_state; undo_cpu_up(cpu, st); break; } } out: cpu_hotplug_done(); return ret; } int cpu_up(unsigned int cpu) { int err = 0; if (!cpu_possible(cpu)) { pr_err("can't online cpu %d because it is not configured as may-hotadd at boot time\n", cpu); #if defined(CONFIG_IA64) pr_err("please check additional_cpus= boot parameter\n"); #endif return -EINVAL; } err = try_online_node(cpu_to_node(cpu)); if (err) return err; cpu_maps_update_begin(); if (cpu_hotplug_disabled) { err = -EBUSY; goto out; } err = _cpu_up(cpu, 0); out: cpu_maps_update_done(); return err; } EXPORT_SYMBOL_GPL(cpu_up); #ifdef CONFIG_PM_SLEEP_SMP static cpumask_var_t frozen_cpus; int disable_nonboot_cpus(void) { int cpu, first_cpu, error = 0; cpu_maps_update_begin(); first_cpu = cpumask_first(cpu_online_mask); /* * 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 */ cpumask_clear(frozen_cpus); pr_info("Disabling non-boot CPUs ...\n"); for_each_online_cpu(cpu) { if (cpu == first_cpu) continue; trace_suspend_resume(TPS("CPU_OFF"), cpu, true); error = _cpu_down(cpu, 1); trace_suspend_resume(TPS("CPU_OFF"), cpu, false); if (!error) cpumask_set_cpu(cpu, frozen_cpus); else { pr_err("Error taking CPU%d down: %d\n", cpu, error); break; } } if (!error) BUG_ON(num_online_cpus() > 1); else pr_err("Non-boot CPUs are not disabled\n"); /* * Make sure the CPUs won't be enabled by someone else. We need to do * this even in case of failure as all disable_nonboot_cpus() users are * supposed to do enable_nonboot_cpus() on the failure path. */ cpu_hotplug_disabled++; cpu_maps_update_done(); return error; } void __weak arch_enable_nonboot_cpus_begin(void) { } void __weak arch_enable_nonboot_cpus_end(void) { } void enable_nonboot_cpus(void) { int cpu, error; /* Allow everyone to use the CPU hotplug again */ cpu_maps_update_begin(); WARN_ON(--cpu_hotplug_disabled < 0); if (cpumask_empty(frozen_cpus)) goto out; pr_info("Enabling non-boot CPUs ...\n"); arch_enable_nonboot_cpus_begin(); for_each_cpu(cpu, frozen_cpus) { trace_suspend_resume(TPS("CPU_ON"), cpu, true); error = _cpu_up(cpu, 1); trace_suspend_resume(TPS("CPU_ON"), cpu, false); if (!error) { pr_info("CPU%d is up\n", cpu); continue; } pr_warn("Error taking CPU%d up: %d\n", cpu, error); } arch_enable_nonboot_cpus_end(); cpumask_clear(frozen_cpus); out: cpu_maps_update_done(); } static int __init alloc_frozen_cpus(void) { if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO)) return -ENOMEM; return 0; } core_initcall(alloc_frozen_cpus); /* * When callbacks for CPU hotplug notifications are being executed, we must * ensure that the state of the system with respect to the tasks being frozen * or not, as reported by the notification, remains unchanged *throughout the * duration* of the execution of the callbacks. * Hence we need to prevent the freezer from racing with regular CPU hotplug. * * This synchronization is implemented by mutually excluding regular CPU * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/ * Hibernate notifications. */ static int cpu_hotplug_pm_callback(struct notifier_block *nb, unsigned long action, void *ptr) { switch (action) { case PM_SUSPEND_PREPARE: case PM_HIBERNATION_PREPARE: cpu_hotplug_disable(); break; case PM_POST_SUSPEND: case PM_POST_HIBERNATION: cpu_hotplug_enable(); break; default: return NOTIFY_DONE; } return NOTIFY_OK; } static int __init cpu_hotplug_pm_sync_init(void) { /* * cpu_hotplug_pm_callback has higher priority than x86 * bsp_pm_callback which depends on cpu_hotplug_pm_callback * to disable cpu hotplug to avoid cpu hotplug race. */ pm_notifier(cpu_hotplug_pm_callback, 0); return 0; } core_initcall(cpu_hotplug_pm_sync_init); #endif /* CONFIG_PM_SLEEP_SMP */ /** * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers * @cpu: cpu that just started * * This function calls the cpu_chain notifiers with CPU_STARTING. * It must be called by the arch code on the new cpu, before the new cpu * enables interrupts and before the "boot" cpu returns from __cpu_up(). */ void notify_cpu_starting(unsigned int cpu) { cpu_notify(CPU_STARTING, cpu); } #endif /* CONFIG_SMP */ /* Boot processor state steps */ static struct cpuhp_step cpuhp_bp_states[] = { [CPUHP_OFFLINE] = { .name = "offline", .startup = NULL, .teardown = NULL, }, #ifdef CONFIG_SMP [CPUHP_CREATE_THREADS]= { .name = "threads:create", .startup = smpboot_create_threads, .teardown = NULL, }, [CPUHP_NOTIFY_PREPARE] = { .name = "notify:prepare", .startup = notify_prepare, .teardown = notify_dead, .skip_onerr = true, }, [CPUHP_BRINGUP_CPU] = { .name = "cpu:bringup", .startup = bringup_cpu, .teardown = takedown_cpu, .skip_onerr = true, }, [CPUHP_NOTIFY_ONLINE] = { .name = "notify:online", .startup = notify_online, .teardown = notify_down_prepare, }, #endif [CPUHP_ONLINE] = { .name = "online", .startup = NULL, .teardown = NULL, }, }; /* * cpu_bit_bitmap[] is a special, "compressed" data structure that * represents all NR_CPUS bits binary values of 1< 32 MASK_DECLARE_8(32), MASK_DECLARE_8(40), MASK_DECLARE_8(48), MASK_DECLARE_8(56), #endif }; EXPORT_SYMBOL_GPL(cpu_bit_bitmap); const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL; EXPORT_SYMBOL(cpu_all_bits); #ifdef CONFIG_INIT_ALL_POSSIBLE struct cpumask __cpu_possible_mask __read_mostly = {CPU_BITS_ALL}; #else struct cpumask __cpu_possible_mask __read_mostly; #endif EXPORT_SYMBOL(__cpu_possible_mask); struct cpumask __cpu_online_mask __read_mostly; EXPORT_SYMBOL(__cpu_online_mask); struct cpumask __cpu_present_mask __read_mostly; EXPORT_SYMBOL(__cpu_present_mask); struct cpumask __cpu_active_mask __read_mostly; EXPORT_SYMBOL(__cpu_active_mask); void init_cpu_present(const struct cpumask *src) { cpumask_copy(&__cpu_present_mask, src); } void init_cpu_possible(const struct cpumask *src) { cpumask_copy(&__cpu_possible_mask, src); } void init_cpu_online(const struct cpumask *src) { cpumask_copy(&__cpu_online_mask, src); } /* * Activate the first processor. */ void __init boot_cpu_init(void) { int cpu = smp_processor_id(); /* Mark the boot cpu "present", "online" etc for SMP and UP case */ set_cpu_online(cpu, true); set_cpu_active(cpu, true); set_cpu_present(cpu, true); set_cpu_possible(cpu, true); } /* * Must be called _AFTER_ setting up the per_cpu areas */ void __init boot_cpu_state_init(void) { per_cpu_ptr(&cpuhp_state, smp_processor_id())->state = CPUHP_ONLINE; }