diff options
Diffstat (limited to 'kernel/smp.c')
| -rw-r--r-- | kernel/smp.c | 607 |
1 files changed, 384 insertions, 223 deletions
diff --git a/kernel/smp.c b/kernel/smp.c index 12ed8b013e2..80c33f8de14 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -6,40 +6,30 @@ #include <linux/rcupdate.h> #include <linux/rculist.h> #include <linux/kernel.h> -#include <linux/module.h> +#include <linux/export.h> #include <linux/percpu.h> #include <linux/init.h> #include <linux/gfp.h> #include <linux/smp.h> #include <linux/cpu.h> -static struct { - struct list_head queue; - raw_spinlock_t lock; -} call_function __cacheline_aligned_in_smp = - { - .queue = LIST_HEAD_INIT(call_function.queue), - .lock = __RAW_SPIN_LOCK_UNLOCKED(call_function.lock), - }; +#include "smpboot.h" enum { CSD_FLAG_LOCK = 0x01, + CSD_FLAG_WAIT = 0x02, }; struct call_function_data { - struct call_single_data csd; - atomic_t refs; + struct call_single_data __percpu *csd; cpumask_var_t cpumask; }; static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_function_data, cfd_data); -struct call_single_queue { - struct list_head list; - raw_spinlock_t lock; -}; +static DEFINE_PER_CPU_SHARED_ALIGNED(struct llist_head, call_single_queue); -static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_queue, call_single_queue); +static void flush_smp_call_function_queue(bool warn_cpu_offline); static int hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu) @@ -53,15 +43,36 @@ hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu) if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL, cpu_to_node(cpu))) return notifier_from_errno(-ENOMEM); + cfd->csd = alloc_percpu(struct call_single_data); + if (!cfd->csd) { + free_cpumask_var(cfd->cpumask); + return notifier_from_errno(-ENOMEM); + } break; #ifdef CONFIG_HOTPLUG_CPU case CPU_UP_CANCELED: case CPU_UP_CANCELED_FROZEN: + /* Fall-through to the CPU_DEAD[_FROZEN] case. */ case CPU_DEAD: case CPU_DEAD_FROZEN: free_cpumask_var(cfd->cpumask); + free_percpu(cfd->csd); + break; + + case CPU_DYING: + case CPU_DYING_FROZEN: + /* + * The IPIs for the smp-call-function callbacks queued by other + * CPUs might arrive late, either due to hardware latencies or + * because this CPU disabled interrupts (inside stop-machine) + * before the IPIs were sent. So flush out any pending callbacks + * explicitly (without waiting for the IPIs to arrive), to + * ensure that the outgoing CPU doesn't go offline with work + * still pending. + */ + flush_smp_call_function_queue(false); break; #endif }; @@ -69,28 +80,21 @@ hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu) return NOTIFY_OK; } -static struct notifier_block __cpuinitdata hotplug_cfd_notifier = { +static struct notifier_block hotplug_cfd_notifier = { .notifier_call = hotplug_cfd, }; -static int __cpuinit init_call_single_data(void) +void __init call_function_init(void) { void *cpu = (void *)(long)smp_processor_id(); int i; - for_each_possible_cpu(i) { - struct call_single_queue *q = &per_cpu(call_single_queue, i); - - raw_spin_lock_init(&q->lock); - INIT_LIST_HEAD(&q->list); - } + for_each_possible_cpu(i) + init_llist_head(&per_cpu(call_single_queue, i)); hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu); register_cpu_notifier(&hotplug_cfd_notifier); - - return 0; } -early_initcall(init_call_single_data); /* * csd_lock/csd_unlock used to serialize access to per-cpu csd resources @@ -99,16 +103,16 @@ early_initcall(init_call_single_data); * previous function call. For multi-cpu calls its even more interesting * as we'll have to ensure no other cpu is observing our csd. */ -static void csd_lock_wait(struct call_single_data *data) +static void csd_lock_wait(struct call_single_data *csd) { - while (data->flags & CSD_FLAG_LOCK) + while (csd->flags & CSD_FLAG_LOCK) cpu_relax(); } -static void csd_lock(struct call_single_data *data) +static void csd_lock(struct call_single_data *csd) { - csd_lock_wait(data); - data->flags = CSD_FLAG_LOCK; + csd_lock_wait(csd); + csd->flags |= CSD_FLAG_LOCK; /* * prevent CPU from reordering the above assignment @@ -118,34 +122,57 @@ static void csd_lock(struct call_single_data *data) smp_mb(); } -static void csd_unlock(struct call_single_data *data) +static void csd_unlock(struct call_single_data *csd) { - WARN_ON(!(data->flags & CSD_FLAG_LOCK)); + WARN_ON((csd->flags & CSD_FLAG_WAIT) && !(csd->flags & CSD_FLAG_LOCK)); /* * ensure we're all done before releasing data: */ smp_mb(); - data->flags &= ~CSD_FLAG_LOCK; + csd->flags &= ~CSD_FLAG_LOCK; } +static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data); + /* * Insert a previously allocated call_single_data element * for execution on the given CPU. data must already have * ->func, ->info, and ->flags set. */ -static -void generic_exec_single(int cpu, struct call_single_data *data, int wait) +static int generic_exec_single(int cpu, struct call_single_data *csd, + smp_call_func_t func, void *info, int wait) { - struct call_single_queue *dst = &per_cpu(call_single_queue, cpu); + struct call_single_data csd_stack = { .flags = 0 }; unsigned long flags; - int ipi; - raw_spin_lock_irqsave(&dst->lock, flags); - ipi = list_empty(&dst->list); - list_add_tail(&data->list, &dst->list); - raw_spin_unlock_irqrestore(&dst->lock, flags); + + if (cpu == smp_processor_id()) { + local_irq_save(flags); + func(info); + local_irq_restore(flags); + return 0; + } + + + if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) + return -ENXIO; + + + if (!csd) { + csd = &csd_stack; + if (!wait) + csd = &__get_cpu_var(csd_data); + } + + csd_lock(csd); + + csd->func = func; + csd->info = info; + + if (wait) + csd->flags |= CSD_FLAG_WAIT; /* * The list addition should be visible before sending the IPI @@ -158,107 +185,74 @@ void generic_exec_single(int cpu, struct call_single_data *data, int wait) * locking and barrier primitives. Generic code isn't really * equipped to do the right thing... */ - if (ipi) + if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu))) arch_send_call_function_single_ipi(cpu); if (wait) - csd_lock_wait(data); + csd_lock_wait(csd); + + return 0; } -/* - * Invoked by arch to handle an IPI for call function. Must be called with - * interrupts disabled. +/** + * generic_smp_call_function_single_interrupt - Execute SMP IPI callbacks + * + * Invoked by arch to handle an IPI for call function single. + * Must be called with interrupts disabled. */ -void generic_smp_call_function_interrupt(void) +void generic_smp_call_function_single_interrupt(void) { - struct call_function_data *data; - int cpu = smp_processor_id(); - - /* - * Shouldn't receive this interrupt on a cpu that is not yet online. - */ - WARN_ON_ONCE(!cpu_online(cpu)); - - /* - * Ensure entry is visible on call_function_queue after we have - * entered the IPI. See comment in smp_call_function_many. - * If we don't have this, then we may miss an entry on the list - * and never get another IPI to process it. - */ - smp_mb(); - - /* - * It's ok to use list_for_each_rcu() here even though we may - * delete 'pos', since list_del_rcu() doesn't clear ->next - */ - list_for_each_entry_rcu(data, &call_function.queue, csd.list) { - int refs; - - if (!cpumask_test_and_clear_cpu(cpu, data->cpumask)) - continue; - - data->csd.func(data->csd.info); - - refs = atomic_dec_return(&data->refs); - WARN_ON(refs < 0); - if (!refs) { - raw_spin_lock(&call_function.lock); - list_del_rcu(&data->csd.list); - raw_spin_unlock(&call_function.lock); - } - - if (refs) - continue; - - csd_unlock(&data->csd); - } - + flush_smp_call_function_queue(true); } -/* - * Invoked by arch to handle an IPI for call function single. Must be - * called from the arch with interrupts disabled. +/** + * flush_smp_call_function_queue - Flush pending smp-call-function callbacks + * + * @warn_cpu_offline: If set to 'true', warn if callbacks were queued on an + * offline CPU. Skip this check if set to 'false'. + * + * Flush any pending smp-call-function callbacks queued on this CPU. This is + * invoked by the generic IPI handler, as well as by a CPU about to go offline, + * to ensure that all pending IPI callbacks are run before it goes completely + * offline. + * + * Loop through the call_single_queue and run all the queued callbacks. + * Must be called with interrupts disabled. */ -void generic_smp_call_function_single_interrupt(void) +static void flush_smp_call_function_queue(bool warn_cpu_offline) { - struct call_single_queue *q = &__get_cpu_var(call_single_queue); - unsigned int data_flags; - LIST_HEAD(list); - - /* - * Shouldn't receive this interrupt on a cpu that is not yet online. - */ - WARN_ON_ONCE(!cpu_online(smp_processor_id())); + struct llist_head *head; + struct llist_node *entry; + struct call_single_data *csd, *csd_next; + static bool warned; - raw_spin_lock(&q->lock); - list_replace_init(&q->list, &list); - raw_spin_unlock(&q->lock); + WARN_ON(!irqs_disabled()); - while (!list_empty(&list)) { - struct call_single_data *data; + head = &__get_cpu_var(call_single_queue); + entry = llist_del_all(head); + entry = llist_reverse_order(entry); - data = list_entry(list.next, struct call_single_data, list); - list_del(&data->list); + /* There shouldn't be any pending callbacks on an offline CPU. */ + if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) && + !warned && !llist_empty(head))) { + warned = true; + WARN(1, "IPI on offline CPU %d\n", smp_processor_id()); /* - * 'data' can be invalid after this call if flags == 0 - * (when called through generic_exec_single()), - * so save them away before making the call: + * We don't have to use the _safe() variant here + * because we are not invoking the IPI handlers yet. */ - data_flags = data->flags; - - data->func(data->info); + llist_for_each_entry(csd, entry, llist) + pr_warn("IPI callback %pS sent to offline CPU\n", + csd->func); + } - /* - * Unlocked CSDs are valid through generic_exec_single(): - */ - if (data_flags & CSD_FLAG_LOCK) - csd_unlock(data); + llist_for_each_entry_safe(csd, csd_next, entry, llist) { + csd->func(csd->info); + csd_unlock(csd); } } -static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data); - /* * smp_call_function_single - Run a function on a specific CPU * @func: The function to run. This must be fast and non-blocking. @@ -270,12 +264,8 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(struct call_single_data, csd_data); int smp_call_function_single(int cpu, smp_call_func_t func, void *info, int wait) { - struct call_single_data d = { - .flags = 0, - }; - unsigned long flags; int this_cpu; - int err = 0; + int err; /* * prevent preemption and reschedule on another processor, @@ -292,32 +282,41 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info, WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled() && !oops_in_progress); - if (cpu == this_cpu) { - local_irq_save(flags); - func(info); - local_irq_restore(flags); - } else { - if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) { - struct call_single_data *data = &d; + err = generic_exec_single(cpu, NULL, func, info, wait); - if (!wait) - data = &__get_cpu_var(csd_data); + put_cpu(); - csd_lock(data); + return err; +} +EXPORT_SYMBOL(smp_call_function_single); - data->func = func; - data->info = info; - generic_exec_single(cpu, data, wait); - } else { - err = -ENXIO; /* CPU not online */ - } - } +/** + * smp_call_function_single_async(): Run an asynchronous function on a + * specific CPU. + * @cpu: The CPU to run on. + * @csd: Pre-allocated and setup data structure + * + * Like smp_call_function_single(), but the call is asynchonous and + * can thus be done from contexts with disabled interrupts. + * + * The caller passes his own pre-allocated data structure + * (ie: embedded in an object) and is responsible for synchronizing it + * such that the IPIs performed on the @csd are strictly serialized. + * + * NOTE: Be careful, there is unfortunately no current debugging facility to + * validate the correctness of this serialization. + */ +int smp_call_function_single_async(int cpu, struct call_single_data *csd) +{ + int err = 0; - put_cpu(); + preempt_disable(); + err = generic_exec_single(cpu, csd, csd->func, csd->info, 0); + preempt_enable(); return err; } -EXPORT_SYMBOL(smp_call_function_single); +EXPORT_SYMBOL_GPL(smp_call_function_single_async); /* * smp_call_function_any - Run a function on any of the given cpus @@ -327,8 +326,6 @@ EXPORT_SYMBOL(smp_call_function_single); * @wait: If true, wait until function has completed. * * Returns 0 on success, else a negative status code (if no cpus were online). - * Note that @wait will be implicitly turned on in case of allocation failures, - * since we fall back to on-stack allocation. * * Selection preference: * 1) current cpu if in @mask @@ -365,43 +362,6 @@ call: EXPORT_SYMBOL_GPL(smp_call_function_any); /** - * __smp_call_function_single(): Run a function on a specific CPU - * @cpu: The CPU to run on. - * @data: Pre-allocated and setup data structure - * @wait: If true, wait until function has completed on specified CPU. - * - * Like smp_call_function_single(), but allow caller to pass in a - * pre-allocated data structure. Useful for embedding @data inside - * other structures, for instance. - */ -void __smp_call_function_single(int cpu, struct call_single_data *data, - int wait) -{ - unsigned int this_cpu; - unsigned long flags; - - this_cpu = get_cpu(); - /* - * Can deadlock when called with interrupts disabled. - * We allow cpu's that are not yet online though, as no one else can - * send smp call function interrupt to this cpu and as such deadlocks - * can't happen. - */ - WARN_ON_ONCE(cpu_online(smp_processor_id()) && wait && irqs_disabled() - && !oops_in_progress); - - if (cpu == this_cpu) { - local_irq_save(flags); - data->func(data->info); - local_irq_restore(flags); - } else { - csd_lock(data); - generic_exec_single(cpu, data, wait); - } - put_cpu(); -} - -/** * smp_call_function_many(): Run a function on a set of other CPUs. * @mask: The set of cpus to run on (only runs on online subset). * @func: The function to run. This must be fast and non-blocking. @@ -418,8 +378,7 @@ void __smp_call_function_single(int cpu, struct call_single_data *data, void smp_call_function_many(const struct cpumask *mask, smp_call_func_t func, void *info, bool wait) { - struct call_function_data *data; - unsigned long flags; + struct call_function_data *cfd; int cpu, next_cpu, this_cpu = smp_processor_id(); /* @@ -429,9 +388,9 @@ void smp_call_function_many(const struct cpumask *mask, * can't happen. */ WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled() - && !oops_in_progress); + && !oops_in_progress && !early_boot_irqs_disabled); - /* So, what's a CPU they want? Ignoring this one. */ + /* Try to fastpath. So, what's a CPU they want? Ignoring this one. */ cpu = cpumask_first_and(mask, cpu_online_mask); if (cpu == this_cpu) cpu = cpumask_next_and(cpu, mask, cpu_online_mask); @@ -451,37 +410,35 @@ void smp_call_function_many(const struct cpumask *mask, return; } - data = &__get_cpu_var(cfd_data); - csd_lock(&data->csd); + cfd = &__get_cpu_var(cfd_data); - data->csd.func = func; - data->csd.info = info; - cpumask_and(data->cpumask, mask, cpu_online_mask); - cpumask_clear_cpu(this_cpu, data->cpumask); - atomic_set(&data->refs, cpumask_weight(data->cpumask)); + cpumask_and(cfd->cpumask, mask, cpu_online_mask); + cpumask_clear_cpu(this_cpu, cfd->cpumask); - raw_spin_lock_irqsave(&call_function.lock, flags); - /* - * Place entry at the _HEAD_ of the list, so that any cpu still - * observing the entry in generic_smp_call_function_interrupt() - * will not miss any other list entries: - */ - list_add_rcu(&data->csd.list, &call_function.queue); - raw_spin_unlock_irqrestore(&call_function.lock, flags); + /* Some callers race with other cpus changing the passed mask */ + if (unlikely(!cpumask_weight(cfd->cpumask))) + return; - /* - * Make the list addition visible before sending the ipi. - * (IPIs must obey or appear to obey normal Linux cache - * coherency rules -- see comment in generic_exec_single). - */ - smp_mb(); + for_each_cpu(cpu, cfd->cpumask) { + struct call_single_data *csd = per_cpu_ptr(cfd->csd, cpu); + + csd_lock(csd); + csd->func = func; + csd->info = info; + llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)); + } /* Send a message to all CPUs in the map */ - arch_send_call_function_ipi_mask(data->cpumask); + arch_send_call_function_ipi_mask(cfd->cpumask); - /* Optionally wait for the CPUs to complete */ - if (wait) - csd_lock_wait(&data->csd); + if (wait) { + for_each_cpu(cpu, cfd->cpumask) { + struct call_single_data *csd; + + csd = per_cpu_ptr(cfd->csd, cpu); + csd_lock_wait(csd); + } + } } EXPORT_SYMBOL(smp_call_function_many); @@ -510,22 +467,226 @@ int smp_call_function(smp_call_func_t func, void *info, int wait) } EXPORT_SYMBOL(smp_call_function); -void ipi_call_lock(void) +/* Setup configured maximum number of CPUs to activate */ +unsigned int setup_max_cpus = NR_CPUS; +EXPORT_SYMBOL(setup_max_cpus); + + +/* + * Setup routine for controlling SMP activation + * + * Command-line option of "nosmp" or "maxcpus=0" will disable SMP + * activation entirely (the MPS table probe still happens, though). + * + * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer + * greater than 0, limits the maximum number of CPUs activated in + * SMP mode to <NUM>. + */ + +void __weak arch_disable_smp_support(void) { } + +static int __init nosmp(char *str) +{ + setup_max_cpus = 0; + arch_disable_smp_support(); + + return 0; +} + +early_param("nosmp", nosmp); + +/* this is hard limit */ +static int __init nrcpus(char *str) +{ + int nr_cpus; + + get_option(&str, &nr_cpus); + if (nr_cpus > 0 && nr_cpus < nr_cpu_ids) + nr_cpu_ids = nr_cpus; + + return 0; +} + +early_param("nr_cpus", nrcpus); + +static int __init maxcpus(char *str) { - raw_spin_lock(&call_function.lock); + get_option(&str, &setup_max_cpus); + if (setup_max_cpus == 0) + arch_disable_smp_support(); + + return 0; } -void ipi_call_unlock(void) +early_param("maxcpus", maxcpus); + +/* Setup number of possible processor ids */ +int nr_cpu_ids __read_mostly = NR_CPUS; +EXPORT_SYMBOL(nr_cpu_ids); + +/* An arch may set nr_cpu_ids earlier if needed, so this would be redundant */ +void __init setup_nr_cpu_ids(void) { - raw_spin_unlock(&call_function.lock); + nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1; } -void ipi_call_lock_irq(void) +void __weak smp_announce(void) { - raw_spin_lock_irq(&call_function.lock); + printk(KERN_INFO "Brought up %d CPUs\n", num_online_cpus()); } -void ipi_call_unlock_irq(void) +/* Called by boot processor to activate the rest. */ +void __init smp_init(void) { - raw_spin_unlock_irq(&call_function.lock); + unsigned int cpu; + + idle_threads_init(); + + /* FIXME: This should be done in userspace --RR */ + for_each_present_cpu(cpu) { + if (num_online_cpus() >= setup_max_cpus) + break; + if (!cpu_online(cpu)) + cpu_up(cpu); + } + + /* Any cleanup work */ + smp_announce(); + smp_cpus_done(setup_max_cpus); +} + +/* + * Call a function on all processors. May be used during early boot while + * early_boot_irqs_disabled is set. Use local_irq_save/restore() instead + * of local_irq_disable/enable(). + */ +int on_each_cpu(void (*func) (void *info), void *info, int wait) +{ + unsigned long flags; + int ret = 0; + + preempt_disable(); + ret = smp_call_function(func, info, wait); + local_irq_save(flags); + func(info); + local_irq_restore(flags); + preempt_enable(); + return ret; +} +EXPORT_SYMBOL(on_each_cpu); + +/** + * on_each_cpu_mask(): Run a function on processors specified by + * cpumask, which may include the local processor. + * @mask: The set of cpus to run on (only runs on online subset). + * @func: The function to run. This must be fast and non-blocking. + * @info: An arbitrary pointer to pass to the function. + * @wait: If true, wait (atomically) until function has completed + * on other CPUs. + * + * If @wait is true, then returns once @func has returned. + * + * You must not call this function with disabled interrupts or from a + * hardware interrupt handler or from a bottom half handler. The + * exception is that it may be used during early boot while + * early_boot_irqs_disabled is set. + */ +void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func, + void *info, bool wait) +{ + int cpu = get_cpu(); + + smp_call_function_many(mask, func, info, wait); + if (cpumask_test_cpu(cpu, mask)) { + unsigned long flags; + local_irq_save(flags); + func(info); + local_irq_restore(flags); + } + put_cpu(); +} +EXPORT_SYMBOL(on_each_cpu_mask); + +/* + * on_each_cpu_cond(): Call a function on each processor for which + * the supplied function cond_func returns true, optionally waiting + * for all the required CPUs to finish. This may include the local + * processor. + * @cond_func: A callback function that is passed a cpu id and + * the the info parameter. The function is called + * with preemption disabled. The function should + * return a blooean value indicating whether to IPI + * the specified CPU. + * @func: The function to run on all applicable CPUs. + * This must be fast and non-blocking. + * @info: An arbitrary pointer to pass to both functions. + * @wait: If true, wait (atomically) until function has + * completed on other CPUs. + * @gfp_flags: GFP flags to use when allocating the cpumask + * used internally by the function. + * + * The function might sleep if the GFP flags indicates a non + * atomic allocation is allowed. + * + * Preemption is disabled to protect against CPUs going offline but not online. + * CPUs going online during the call will not be seen or sent an IPI. + * + * You must not call this function with disabled interrupts or + * from a hardware interrupt handler or from a bottom half handler. + */ +void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info), + smp_call_func_t func, void *info, bool wait, + gfp_t gfp_flags) +{ + cpumask_var_t cpus; + int cpu, ret; + + might_sleep_if(gfp_flags & __GFP_WAIT); + + if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) { + preempt_disable(); + for_each_online_cpu(cpu) + if (cond_func(cpu, info)) + cpumask_set_cpu(cpu, cpus); + on_each_cpu_mask(cpus, func, info, wait); + preempt_enable(); + free_cpumask_var(cpus); + } else { + /* + * No free cpumask, bother. No matter, we'll + * just have to IPI them one by one. + */ + preempt_disable(); + for_each_online_cpu(cpu) + if (cond_func(cpu, info)) { + ret = smp_call_function_single(cpu, func, + info, wait); + WARN_ON_ONCE(!ret); + } + preempt_enable(); + } +} +EXPORT_SYMBOL(on_each_cpu_cond); + +static void do_nothing(void *unused) +{ +} + +/** + * kick_all_cpus_sync - Force all cpus out of idle + * + * Used to synchronize the update of pm_idle function pointer. It's + * called after the pointer is updated and returns after the dummy + * callback function has been executed on all cpus. The execution of + * the function can only happen on the remote cpus after they have + * left the idle function which had been called via pm_idle function + * pointer. So it's guaranteed that nothing uses the previous pointer + * anymore. + */ +void kick_all_cpus_sync(void) +{ + /* Make sure the change is visible before we kick the cpus */ + smp_mb(); + smp_call_function(do_nothing, NULL, 1); } +EXPORT_SYMBOL_GPL(kick_all_cpus_sync); |