/* * Generic helpers for smp ipi calls * * (C) Jens Axboe <jens.axboe@oracle.com> 2008 */#include <linux/rcupdate.h>#include <linux/rculist.h>#include <linux/kernel.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> #include "smpboot.h" #ifdef CONFIG_USE_GENERIC_SMP_HELPERSenum { CSD_FLAG_LOCK = 0x01,}; struct call_function_data { struct call_single_data __percpu *csd; cpumask_var_t cpumask; cpumask_var_t cpumask_ipi;}; 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 call_single_queue, call_single_queue); static inthotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu){ long cpu = (long)hcpu; struct call_function_data *cfd = &per_cpu(cfd_data, cpu); switch (action) { case CPU_UP_PREPARE: case CPU_UP_PREPARE_FROZEN: if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL, cpu_to_node(cpu))) return notifier_from_errno(-ENOMEM); if (!zalloc_cpumask_var_node(&cfd->cpumask_ipi, 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: case CPU_DEAD: case CPU_DEAD_FROZEN: free_cpumask_var(cfd->cpumask); free_cpumask_var(cfd->cpumask_ipi); free_percpu(cfd->csd); break;#endif }; return NOTIFY_OK;} static struct notifier_block hotplug_cfd_notifier = { .notifier_call = hotplug_cfd,}; 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); } hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu); register_cpu_notifier(&hotplug_cfd_notifier);} /* * csd_lock/csd_unlock used to serialize access to per-cpu csd resources * * For non-synchronous ipi calls the csd can still be in use by the * 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 *csd){ while (csd->flags & CSD_FLAG_LOCK) cpu_relax();} static void csd_lock(struct call_single_data *csd){ csd_lock_wait(csd); csd->flags |= CSD_FLAG_LOCK; /* * prevent CPU from reordering the above assignment * to ->flags with any subsequent assignments to other * fields of the specified call_single_data structure: */ smp_mb();} static void csd_unlock(struct call_single_data *csd){ WARN_ON(!(csd->flags & CSD_FLAG_LOCK)); /* * ensure we're all done before releasing data: */ smp_mb(); csd->flags &= ~CSD_FLAG_LOCK;} /* * Insert a previously allocated call_single_data element * for execution on the given CPU. data must already have * ->func, ->info, and ->flags set. */staticvoid generic_exec_single(int cpu, struct call_single_data *csd, int wait){ struct call_single_queue *dst = &per_cpu(call_single_queue, cpu); unsigned long flags; int ipi; raw_spin_lock_irqsave(&dst->lock, flags); ipi = list_empty(&dst->list); list_add_tail(&csd->list, &dst->list); raw_spin_unlock_irqrestore(&dst->lock, flags); /* * The list addition should be visible before sending the IPI * handler locks the list to pull the entry off it because of * normal cache coherency rules implied by spinlocks. * * If IPIs can go out of order to the cache coherency protocol * in an architecture, sufficient synchronisation should be added * to arch code to make it appear to obey cache coherency WRT * locking and barrier primitives. Generic code isn't really * equipped to do the right thing... */ if (ipi) arch_send_call_function_single_ipi(cpu); if (wait) csd_lock_wait(csd);} /* * Invoked by arch to handle an IPI for call function single. Must be * called from the arch with interrupts disabled. */void generic_smp_call_function_single_interrupt(void){ struct call_single_queue *q = &__get_cpu_var(call_single_queue); LIST_HEAD(list); /* * Shouldn't receive this interrupt on a cpu that is not yet online. */ WARN_ON_ONCE(!cpu_online(smp_processor_id())); raw_spin_lock(&q->lock); list_replace_init(&q->list, &list); raw_spin_unlock(&q->lock); while (!list_empty(&list)) { struct call_single_data *csd; unsigned int csd_flags; csd = list_entry(list.next, struct call_single_data, list); list_del(&csd->list); /* * 'csd' can be invalid after this call if flags == 0 * (when called through generic_exec_single()), * so save them away before making the call: */ csd_flags = csd->flags; csd->func(csd->info); /* * Unlocked CSDs are valid through generic_exec_single(): */ if (csd_flags & CSD_FLAG_LOCK) 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. * @info: An arbitrary pointer to pass to the function. * @wait: If true, wait until function has completed on other CPUs. * * Returns 0 on success, else a negative status code. */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; /* * prevent preemption and reschedule on another processor, * as well as CPU removal */ 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(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 *csd = &d; if (!wait) csd = &__get_cpu_var(csd_data); csd_lock(csd); csd->func = func; csd->info = info; generic_exec_single(cpu, csd, wait); } else { err = -ENXIO; /* CPU not online */ } } put_cpu(); return err;}EXPORT_SYMBOL(smp_call_function_single); /* * smp_call_function_any - Run a function on any of the given cpus * @mask: The mask of cpus it can run on. * @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 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 * 2) any cpu of current node if in @mask * 3) any other online cpu in @mask */int smp_call_function_any(const struct cpumask *mask, smp_call_func_t func, void *info, int wait){ unsigned int cpu; const struct cpumask *nodemask; int ret; /* Try for same CPU (cheapest) */ cpu = get_cpu(); if (cpumask_test_cpu(cpu, mask)) goto call; /* Try for same node. */ nodemask = cpumask_of_node(cpu_to_node(cpu)); for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids; cpu = cpumask_next_and(cpu, nodemask, mask)) { if (cpu_online(cpu)) goto call; } /* Any online will do: smp_call_function_single handles nr_cpu_ids. */ cpu = cpumask_any_and(mask, cpu_online_mask);call: ret = smp_call_function_single(cpu, func, info, wait); put_cpu(); return ret;}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 *csd, 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); csd->func(csd->info); local_irq_restore(flags); } else { csd_lock(csd); generic_exec_single(cpu, csd, 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. * @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. Preemption * must be disabled when calling this function. */void smp_call_function_many(const struct cpumask *mask, smp_call_func_t func, void *info, bool wait){ struct call_function_data *cfd; int cpu, next_cpu, this_cpu = smp_processor_id(); /* * 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(this_cpu) && irqs_disabled() && !oops_in_progress && !early_boot_irqs_disabled); /* 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); /* No online cpus? We're done. */ if (cpu >= nr_cpu_ids) return; /* Do we have another CPU which isn't us? */ next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask); if (next_cpu == this_cpu) next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask); /* Fastpath: do that cpu by itself. */ if (next_cpu >= nr_cpu_ids) { smp_call_function_single(cpu, func, info, wait); return; } cfd = &__get_cpu_var(cfd_data); cpumask_and(cfd->cpumask, mask, cpu_online_mask); cpumask_clear_cpu(this_cpu, cfd->cpumask); /* Some callers race with other cpus changing the passed mask */ if (unlikely(!cpumask_weight(cfd->cpumask))) return; /* * After we put an entry into the list, cfd->cpumask may be cleared * again when another CPU sends another IPI for a SMP function call, so * cfd->cpumask will be zero. */ cpumask_copy(cfd->cpumask_ipi, cfd->cpumask); for_each_cpu(cpu, cfd->cpumask) { struct call_single_data *csd = per_cpu_ptr(cfd->csd, cpu); struct call_single_queue *dst = &per_cpu(call_single_queue, cpu); unsigned long flags; csd_lock(csd); csd->func = func; csd->info = info; raw_spin_lock_irqsave(&dst->lock, flags); list_add_tail(&csd->list, &dst->list); raw_spin_unlock_irqrestore(&dst->lock, flags); } /* Send a message to all CPUs in the map */ arch_send_call_function_ipi_mask(cfd->cpumask_ipi); 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); /** * smp_call_function(): Run a function on all other CPUs. * @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. * * Returns 0. * * If @wait is true, then returns once @func has returned; otherwise * it returns just before the target cpu calls @func. * * You must not call this function with disabled interrupts or from a * hardware interrupt handler or from a bottom half handler. */int smp_call_function(smp_call_func_t func, void *info, int wait){ preempt_disable(); smp_call_function_many(cpu_online_mask, func, info, wait); preempt_enable(); return 0;}EXPORT_SYMBOL(smp_call_function);#endif /* USE_GENERIC_SMP_HELPERS */ /* 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;} Lines 1–500 of 689. 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/* * Generic helpers for smp ipi calls * * (C) Jens Axboe <jens.axboe@oracle.com> 2008 */ #include <linux/rcupdate.h> #include <linux/rculist.h> #include <linux/kernel.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> #include "smpboot.h" #ifdef CONFIG_USE_GENERIC_SMP_HELPERS enum { CSD_FLAG_LOCK = 0x01, }; struct call_function_data { struct call_single_data __percpu *csd; cpumask_var_t cpumask; cpumask_var_t cpumask_ipi; }; 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 call_single_queue, call_single_queue); static int hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu) { long cpu = (long)hcpu; struct call_function_data *cfd = &per_cpu(cfd_data, cpu); switch (action) { case CPU_UP_PREPARE: case CPU_UP_PREPARE_FROZEN: if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL, cpu_to_node(cpu))) return notifier_from_errno(-ENOMEM); if (!zalloc_cpumask_var_node(&cfd->cpumask_ipi, 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: case CPU_DEAD: case CPU_DEAD_FROZEN: free_cpumask_var(cfd->cpumask); free_cpumask_var(cfd->cpumask_ipi); free_percpu(cfd->csd); break; #endif }; return NOTIFY_OK; } static struct notifier_block hotplug_cfd_notifier = { .notifier_call = hotplug_cfd, }; 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); } hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu); register_cpu_notifier(&hotplug_cfd_notifier); } /* * csd_lock/csd_unlock used to serialize access to per-cpu csd resources * * For non-synchronous ipi calls the csd can still be in use by the * 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 *csd) { while (csd->flags & CSD_FLAG_LOCK) cpu_relax(); } static void csd_lock(struct call_single_data *csd) { csd_lock_wait(csd); csd->flags |= CSD_FLAG_LOCK; /* * prevent CPU from reordering the above assignment * to ->flags with any subsequent assignments to other * fields of the specified call_single_data structure: */ smp_mb(); } static void csd_unlock(struct call_single_data *csd) { WARN_ON(!(csd->flags & CSD_FLAG_LOCK)); /* * ensure we're all done before releasing data: */ smp_mb(); csd->flags &= ~CSD_FLAG_LOCK; } /* * 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 *csd, int wait) { struct call_single_queue *dst = &per_cpu(call_single_queue, cpu); unsigned long flags; int ipi; raw_spin_lock_irqsave(&dst->lock, flags); ipi = list_empty(&dst->list); list_add_tail(&csd->list, &dst->list); raw_spin_unlock_irqrestore(&dst->lock, flags); /* * The list addition should be visible before sending the IPI * handler locks the list to pull the entry off it because of * normal cache coherency rules implied by spinlocks. * * If IPIs can go out of order to the cache coherency protocol * in an architecture, sufficient synchronisation should be added * to arch code to make it appear to obey cache coherency WRT * locking and barrier primitives. Generic code isn't really * equipped to do the right thing... */ if (ipi) arch_send_call_function_single_ipi(cpu); if (wait) csd_lock_wait(csd); } /* * Invoked by arch to handle an IPI for call function single. Must be * called from the arch with interrupts disabled. */ void generic_smp_call_function_single_interrupt(void) { struct call_single_queue *q = &__get_cpu_var(call_single_queue); LIST_HEAD(list); /* * Shouldn't receive this interrupt on a cpu that is not yet online. */ WARN_ON_ONCE(!cpu_online(smp_processor_id())); raw_spin_lock(&q->lock); list_replace_init(&q->list, &list); raw_spin_unlock(&q->lock); while (!list_empty(&list)) { struct call_single_data *csd; unsigned int csd_flags; csd = list_entry(list.next, struct call_single_data, list); list_del(&csd->list); /* * 'csd' can be invalid after this call if flags == 0 * (when called through generic_exec_single()), * so save them away before making the call: */ csd_flags = csd->flags; csd->func(csd->info); /* * Unlocked CSDs are valid through generic_exec_single(): */ if (csd_flags & CSD_FLAG_LOCK) 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. * @info: An arbitrary pointer to pass to the function. * @wait: If true, wait until function has completed on other CPUs. * * Returns 0 on success, else a negative status code. */ 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; /* * prevent preemption and reschedule on another processor, * as well as CPU removal */ 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(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 *csd = &d; if (!wait) csd = &__get_cpu_var(csd_data); csd_lock(csd); csd->func = func; csd->info = info; generic_exec_single(cpu, csd, wait); } else { err = -ENXIO; /* CPU not online */ } } put_cpu(); return err; } EXPORT_SYMBOL(smp_call_function_single); /* * smp_call_function_any - Run a function on any of the given cpus * @mask: The mask of cpus it can run on. * @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 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 * 2) any cpu of current node if in @mask * 3) any other online cpu in @mask */ int smp_call_function_any(const struct cpumask *mask, smp_call_func_t func, void *info, int wait) { unsigned int cpu; const struct cpumask *nodemask; int ret; /* Try for same CPU (cheapest) */ cpu = get_cpu(); if (cpumask_test_cpu(cpu, mask)) goto call; /* Try for same node. */ nodemask = cpumask_of_node(cpu_to_node(cpu)); for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids; cpu = cpumask_next_and(cpu, nodemask, mask)) { if (cpu_online(cpu)) goto call; } /* Any online will do: smp_call_function_single handles nr_cpu_ids. */ cpu = cpumask_any_and(mask, cpu_online_mask); call: ret = smp_call_function_single(cpu, func, info, wait); put_cpu(); return ret; } 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 *csd, 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); csd->func(csd->info); local_irq_restore(flags); } else { csd_lock(csd); generic_exec_single(cpu, csd, 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. * @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. Preemption * must be disabled when calling this function. */ void smp_call_function_many(const struct cpumask *mask, smp_call_func_t func, void *info, bool wait) { struct call_function_data *cfd; int cpu, next_cpu, this_cpu = smp_processor_id(); /* * 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(this_cpu) && irqs_disabled() && !oops_in_progress && !early_boot_irqs_disabled); /* 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); /* No online cpus? We're done. */ if (cpu >= nr_cpu_ids) return; /* Do we have another CPU which isn't us? */ next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask); if (next_cpu == this_cpu) next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask); /* Fastpath: do that cpu by itself. */ if (next_cpu >= nr_cpu_ids) { smp_call_function_single(cpu, func, info, wait); return; } cfd = &__get_cpu_var(cfd_data); cpumask_and(cfd->cpumask, mask, cpu_online_mask); cpumask_clear_cpu(this_cpu, cfd->cpumask); /* Some callers race with other cpus changing the passed mask */ if (unlikely(!cpumask_weight(cfd->cpumask))) return; /* * After we put an entry into the list, cfd->cpumask may be cleared * again when another CPU sends another IPI for a SMP function call, so * cfd->cpumask will be zero. */ cpumask_copy(cfd->cpumask_ipi, cfd->cpumask); for_each_cpu(cpu, cfd->cpumask) { struct call_single_data *csd = per_cpu_ptr(cfd->csd, cpu); struct call_single_queue *dst = &per_cpu(call_single_queue, cpu); unsigned long flags; csd_lock(csd); csd->func = func; csd->info = info; raw_spin_lock_irqsave(&dst->lock, flags); list_add_tail(&csd->list, &dst->list); raw_spin_unlock_irqrestore(&dst->lock, flags); } /* Send a message to all CPUs in the map */ arch_send_call_function_ipi_mask(cfd->cpumask_ipi); 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); /** * smp_call_function(): Run a function on all other CPUs. * @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. * * Returns 0. * * If @wait is true, then returns once @func has returned; otherwise * it returns just before the target cpu calls @func. * * You must not call this function with disabled interrupts or from a * hardware interrupt handler or from a bottom half handler. */ int smp_call_function(smp_call_func_t func, void *info, int wait) { preempt_disable(); smp_call_function_many(cpu_online_mask, func, info, wait); preempt_enable(); return 0; } EXPORT_SYMBOL(smp_call_function); #endif /* USE_GENERIC_SMP_HELPERS */ /* 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; }