| /* |
| * Generic helpers for smp ipi calls |
| * |
| * (C) Jens Axboe <jens.axboe@oracle.com> 2008 |
| * |
| */ |
| #include <linux/init.h> |
| #include <linux/module.h> |
| #include <linux/percpu.h> |
| #include <linux/rcupdate.h> |
| #include <linux/smp.h> |
| |
| static DEFINE_PER_CPU(struct call_single_queue, call_single_queue); |
| static LIST_HEAD(call_function_queue); |
| __cacheline_aligned_in_smp DEFINE_SPINLOCK(call_function_lock); |
| |
| enum { |
| CSD_FLAG_WAIT = 0x01, |
| CSD_FLAG_ALLOC = 0x02, |
| }; |
| |
| struct call_function_data { |
| struct call_single_data csd; |
| spinlock_t lock; |
| unsigned int refs; |
| cpumask_t cpumask; |
| struct rcu_head rcu_head; |
| }; |
| |
| struct call_single_queue { |
| struct list_head list; |
| spinlock_t lock; |
| }; |
| |
| void __cpuinit init_call_single_data(void) |
| { |
| int i; |
| |
| for_each_possible_cpu(i) { |
| struct call_single_queue *q = &per_cpu(call_single_queue, i); |
| |
| spin_lock_init(&q->lock); |
| INIT_LIST_HEAD(&q->list); |
| } |
| } |
| |
| static void csd_flag_wait(struct call_single_data *data) |
| { |
| /* Wait for response */ |
| do { |
| /* |
| * We need to see the flags store in the IPI handler |
| */ |
| smp_mb(); |
| if (!(data->flags & CSD_FLAG_WAIT)) |
| break; |
| cpu_relax(); |
| } while (1); |
| } |
| |
| /* |
| * 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) |
| { |
| struct call_single_queue *dst = &per_cpu(call_single_queue, cpu); |
| int wait = data->flags & CSD_FLAG_WAIT, ipi; |
| unsigned long flags; |
| |
| spin_lock_irqsave(&dst->lock, flags); |
| ipi = list_empty(&dst->list); |
| list_add_tail(&data->list, &dst->list); |
| spin_unlock_irqrestore(&dst->lock, flags); |
| |
| if (ipi) |
| arch_send_call_function_single_ipi(cpu); |
| |
| if (wait) |
| csd_flag_wait(data); |
| } |
| |
| static void rcu_free_call_data(struct rcu_head *head) |
| { |
| struct call_function_data *data; |
| |
| data = container_of(head, struct call_function_data, rcu_head); |
| |
| kfree(data); |
| } |
| |
| /* |
| * Invoked by arch to handle an IPI for call function. Must be called with |
| * interrupts disabled. |
| */ |
| void generic_smp_call_function_interrupt(void) |
| { |
| struct call_function_data *data; |
| int cpu = get_cpu(); |
| |
| /* |
| * It's ok to use list_for_each_rcu() here even though we may delete |
| * 'pos', since list_del_rcu() doesn't clear ->next |
| */ |
| rcu_read_lock(); |
| list_for_each_entry_rcu(data, &call_function_queue, csd.list) { |
| int refs; |
| |
| if (!cpu_isset(cpu, data->cpumask)) |
| continue; |
| |
| data->csd.func(data->csd.info); |
| |
| spin_lock(&data->lock); |
| cpu_clear(cpu, data->cpumask); |
| WARN_ON(data->refs == 0); |
| data->refs--; |
| refs = data->refs; |
| spin_unlock(&data->lock); |
| |
| if (refs) |
| continue; |
| |
| spin_lock(&call_function_lock); |
| list_del_rcu(&data->csd.list); |
| spin_unlock(&call_function_lock); |
| |
| if (data->csd.flags & CSD_FLAG_WAIT) { |
| /* |
| * serialize stores to data with the flag clear |
| * and wakeup |
| */ |
| smp_wmb(); |
| data->csd.flags &= ~CSD_FLAG_WAIT; |
| } else |
| call_rcu(&data->rcu_head, rcu_free_call_data); |
| } |
| rcu_read_unlock(); |
| |
| put_cpu(); |
| } |
| |
| /* |
| * 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); |
| |
| /* |
| * Need to see other stores to list head for checking whether |
| * list is empty without holding q->lock |
| */ |
| smp_mb(); |
| while (!list_empty(&q->list)) { |
| unsigned int data_flags; |
| |
| spin_lock(&q->lock); |
| list_replace_init(&q->list, &list); |
| spin_unlock(&q->lock); |
| |
| while (!list_empty(&list)) { |
| struct call_single_data *data; |
| |
| data = list_entry(list.next, struct call_single_data, |
| list); |
| list_del(&data->list); |
| |
| /* |
| * 'data' can be invalid after this call if |
| * flags == 0 (when called through |
| * generic_exec_single(), so save them away before |
| * making the call. |
| */ |
| data_flags = data->flags; |
| |
| data->func(data->info); |
| |
| if (data_flags & CSD_FLAG_WAIT) { |
| smp_wmb(); |
| data->flags &= ~CSD_FLAG_WAIT; |
| } else if (data_flags & CSD_FLAG_ALLOC) |
| kfree(data); |
| } |
| /* |
| * See comment on outer loop |
| */ |
| smp_mb(); |
| } |
| } |
| |
| /* |
| * 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. |
| * @retry: Unused |
| * @wait: If true, wait until function has completed on other CPUs. |
| * |
| * Returns 0 on success, else a negative status code. Note that @wait |
| * will be implicitly turned on in case of allocation failures, since |
| * we fall back to on-stack allocation. |
| */ |
| int smp_call_function_single(int cpu, void (*func) (void *info), void *info, |
| int retry, int wait) |
| { |
| struct call_single_data d; |
| unsigned long flags; |
| /* prevent preemption and reschedule on another processor */ |
| int me = get_cpu(); |
| |
| /* Can deadlock when called with interrupts disabled */ |
| WARN_ON(irqs_disabled()); |
| |
| if (cpu == me) { |
| local_irq_save(flags); |
| func(info); |
| local_irq_restore(flags); |
| } else { |
| struct call_single_data *data = NULL; |
| |
| if (!wait) { |
| data = kmalloc(sizeof(*data), GFP_ATOMIC); |
| if (data) |
| data->flags = CSD_FLAG_ALLOC; |
| } |
| if (!data) { |
| data = &d; |
| data->flags = CSD_FLAG_WAIT; |
| } |
| |
| data->func = func; |
| data->info = info; |
| generic_exec_single(cpu, data); |
| } |
| |
| put_cpu(); |
| return 0; |
| } |
| EXPORT_SYMBOL(smp_call_function_single); |
| |
| /** |
| * __smp_call_function_single(): Run a function on another CPU |
| * @cpu: The CPU to run on. |
| * @data: Pre-allocated and setup data structure |
| * |
| * 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) |
| { |
| /* Can deadlock when called with interrupts disabled */ |
| WARN_ON((data->flags & CSD_FLAG_WAIT) && irqs_disabled()); |
| |
| generic_exec_single(cpu, data); |
| } |
| |
| /** |
| * smp_call_function_mask(): Run a function on a set of other CPUs. |
| * @mask: The set of cpus to 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 (atomically) until function has completed on other CPUs. |
| * |
| * Returns 0 on success, else a negative status code. |
| * |
| * If @wait is true, then returns once @func has returned. Note that @wait |
| * will be implicitly turned on in case of allocation failures, since |
| * we fall back to on-stack allocation. |
| * |
| * 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. |
| */ |
| int smp_call_function_mask(cpumask_t mask, void (*func)(void *), void *info, |
| int wait) |
| { |
| struct call_function_data d; |
| struct call_function_data *data = NULL; |
| cpumask_t allbutself; |
| unsigned long flags; |
| int cpu, num_cpus; |
| |
| /* Can deadlock when called with interrupts disabled */ |
| WARN_ON(irqs_disabled()); |
| |
| cpu = smp_processor_id(); |
| allbutself = cpu_online_map; |
| cpu_clear(cpu, allbutself); |
| cpus_and(mask, mask, allbutself); |
| num_cpus = cpus_weight(mask); |
| |
| /* |
| * If zero CPUs, return. If just a single CPU, turn this request |
| * into a targetted single call instead since it's faster. |
| */ |
| if (!num_cpus) |
| return 0; |
| else if (num_cpus == 1) { |
| cpu = first_cpu(mask); |
| return smp_call_function_single(cpu, func, info, 0, wait); |
| } |
| |
| if (!wait) { |
| data = kmalloc(sizeof(*data), GFP_ATOMIC); |
| if (data) |
| data->csd.flags = CSD_FLAG_ALLOC; |
| } |
| if (!data) { |
| data = &d; |
| data->csd.flags = CSD_FLAG_WAIT; |
| } |
| |
| spin_lock_init(&data->lock); |
| data->csd.func = func; |
| data->csd.info = info; |
| data->refs = num_cpus; |
| data->cpumask = mask; |
| |
| spin_lock_irqsave(&call_function_lock, flags); |
| list_add_tail_rcu(&data->csd.list, &call_function_queue); |
| spin_unlock_irqrestore(&call_function_lock, flags); |
| |
| /* Send a message to all CPUs in the map */ |
| arch_send_call_function_ipi(mask); |
| |
| /* optionally wait for the CPUs to complete */ |
| if (wait) |
| csd_flag_wait(&data->csd); |
| |
| return 0; |
| } |
| EXPORT_SYMBOL(smp_call_function_mask); |
| |
| /** |
| * 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. |
| * @natomic: Unused |
| * @wait: If true, wait (atomically) until function has completed on other CPUs. |
| * |
| * Returns 0 on success, else a negative status code. |
| * |
| * If @wait is true, then returns once @func has returned; otherwise |
| * it returns just before the target cpu calls @func. In case of allocation |
| * failure, @wait will be implicitly turned on. |
| * |
| * 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(void (*func)(void *), void *info, int natomic, int wait) |
| { |
| int ret; |
| |
| preempt_disable(); |
| ret = smp_call_function_mask(cpu_online_map, func, info, wait); |
| preempt_enable(); |
| return ret; |
| } |
| EXPORT_SYMBOL(smp_call_function); |
| |
| void ipi_call_lock(void) |
| { |
| spin_lock(&call_function_lock); |
| } |
| |
| void ipi_call_unlock(void) |
| { |
| spin_unlock(&call_function_lock); |
| } |
| |
| void ipi_call_lock_irq(void) |
| { |
| spin_lock_irq(&call_function_lock); |
| } |
| |
| void ipi_call_unlock_irq(void) |
| { |
| spin_unlock_irq(&call_function_lock); |
| } |