| /* |
| * 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))) { |
| free_cpumask_var(cfd->cpumask); |
| return notifier_from_errno(-ENOMEM); |
| } |
| cfd->csd = alloc_percpu(struct call_single_data); |
| if (!cfd->csd) { |
| free_cpumask_var(cfd->cpumask_ipi); |
| 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; |
| |
| csd = list_entry(list.next, struct call_single_data, list); |
| list_del(&csd->list); |
| |
| 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. |
| * @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). |
| * |
| * 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; |
| } |
| |
| 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) |
| { |
| get_option(&str, &setup_max_cpus); |
| if (setup_max_cpus == 0) |
| arch_disable_smp_support(); |
| |
| return 0; |
| } |
| |
| 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) |
| { |
| nr_cpu_ids = find_last_bit(cpumask_bits(cpu_possible_mask),NR_CPUS) + 1; |
| } |
| |
| void __weak smp_announce(void) |
| { |
| printk(KERN_INFO "Brought up %d CPUs\n", num_online_cpus()); |
| } |
| |
| /* Called by boot processor to activate the rest. */ |
| void __init smp_init(void) |
| { |
| 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); |