mirror of https://gitee.com/openkylin/linux.git
521 lines
13 KiB
C
521 lines
13 KiB
C
/*
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* Generic helpers for smp ipi calls
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*
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* (C) Jens Axboe <jens.axboe@oracle.com> 2008
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*/
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#include <linux/rcupdate.h>
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#include <linux/rculist.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/percpu.h>
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#include <linux/init.h>
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#include <linux/smp.h>
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#include <linux/cpu.h>
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static DEFINE_PER_CPU(struct call_single_queue, call_single_queue);
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static struct {
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struct list_head queue;
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spinlock_t lock;
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} call_function __cacheline_aligned_in_smp =
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{
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.queue = LIST_HEAD_INIT(call_function.queue),
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.lock = __SPIN_LOCK_UNLOCKED(call_function.lock),
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};
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enum {
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CSD_FLAG_LOCK = 0x01,
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};
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struct call_function_data {
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struct call_single_data csd;
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atomic_t refs;
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cpumask_var_t cpumask;
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};
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struct call_single_queue {
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struct list_head list;
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spinlock_t lock;
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};
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static DEFINE_PER_CPU(struct call_function_data, cfd_data);
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static int
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hotplug_cfd(struct notifier_block *nfb, unsigned long action, void *hcpu)
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{
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long cpu = (long)hcpu;
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struct call_function_data *cfd = &per_cpu(cfd_data, cpu);
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switch (action) {
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case CPU_UP_PREPARE:
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case CPU_UP_PREPARE_FROZEN:
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if (!zalloc_cpumask_var_node(&cfd->cpumask, GFP_KERNEL,
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cpu_to_node(cpu)))
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return NOTIFY_BAD;
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break;
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#ifdef CONFIG_HOTPLUG_CPU
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case CPU_UP_CANCELED:
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case CPU_UP_CANCELED_FROZEN:
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case CPU_DEAD:
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case CPU_DEAD_FROZEN:
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free_cpumask_var(cfd->cpumask);
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break;
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#endif
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};
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return NOTIFY_OK;
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}
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static struct notifier_block __cpuinitdata hotplug_cfd_notifier = {
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.notifier_call = hotplug_cfd,
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};
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static int __cpuinit init_call_single_data(void)
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{
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void *cpu = (void *)(long)smp_processor_id();
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int i;
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for_each_possible_cpu(i) {
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struct call_single_queue *q = &per_cpu(call_single_queue, i);
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spin_lock_init(&q->lock);
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INIT_LIST_HEAD(&q->list);
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}
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hotplug_cfd(&hotplug_cfd_notifier, CPU_UP_PREPARE, cpu);
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register_cpu_notifier(&hotplug_cfd_notifier);
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return 0;
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}
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early_initcall(init_call_single_data);
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/*
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* csd_lock/csd_unlock used to serialize access to per-cpu csd resources
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*
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* For non-synchronous ipi calls the csd can still be in use by the
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* previous function call. For multi-cpu calls its even more interesting
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* as we'll have to ensure no other cpu is observing our csd.
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*/
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static void csd_lock_wait(struct call_single_data *data)
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{
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while (data->flags & CSD_FLAG_LOCK)
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cpu_relax();
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}
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static void csd_lock(struct call_single_data *data)
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{
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csd_lock_wait(data);
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data->flags = CSD_FLAG_LOCK;
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/*
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* prevent CPU from reordering the above assignment
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* to ->flags with any subsequent assignments to other
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* fields of the specified call_single_data structure:
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*/
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smp_mb();
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}
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static void csd_unlock(struct call_single_data *data)
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{
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WARN_ON(!(data->flags & CSD_FLAG_LOCK));
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/*
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* ensure we're all done before releasing data:
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*/
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smp_mb();
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data->flags &= ~CSD_FLAG_LOCK;
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}
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/*
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* Insert a previously allocated call_single_data element
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* for execution on the given CPU. data must already have
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* ->func, ->info, and ->flags set.
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*/
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static
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void generic_exec_single(int cpu, struct call_single_data *data, int wait)
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{
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struct call_single_queue *dst = &per_cpu(call_single_queue, cpu);
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unsigned long flags;
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int ipi;
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spin_lock_irqsave(&dst->lock, flags);
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ipi = list_empty(&dst->list);
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list_add_tail(&data->list, &dst->list);
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spin_unlock_irqrestore(&dst->lock, flags);
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/*
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* The list addition should be visible before sending the IPI
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* handler locks the list to pull the entry off it because of
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* normal cache coherency rules implied by spinlocks.
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*
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* If IPIs can go out of order to the cache coherency protocol
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* in an architecture, sufficient synchronisation should be added
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* to arch code to make it appear to obey cache coherency WRT
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* locking and barrier primitives. Generic code isn't really
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* equipped to do the right thing...
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*/
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if (ipi)
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arch_send_call_function_single_ipi(cpu);
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if (wait)
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csd_lock_wait(data);
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}
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/*
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* Invoked by arch to handle an IPI for call function. Must be called with
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* interrupts disabled.
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*/
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void generic_smp_call_function_interrupt(void)
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{
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struct call_function_data *data;
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int cpu = get_cpu();
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/*
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* Shouldn't receive this interrupt on a cpu that is not yet online.
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*/
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WARN_ON_ONCE(!cpu_online(cpu));
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/*
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* Ensure entry is visible on call_function_queue after we have
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* entered the IPI. See comment in smp_call_function_many.
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* If we don't have this, then we may miss an entry on the list
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* and never get another IPI to process it.
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*/
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smp_mb();
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/*
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* It's ok to use list_for_each_rcu() here even though we may
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* delete 'pos', since list_del_rcu() doesn't clear ->next
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*/
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list_for_each_entry_rcu(data, &call_function.queue, csd.list) {
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int refs;
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if (!cpumask_test_and_clear_cpu(cpu, data->cpumask))
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continue;
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data->csd.func(data->csd.info);
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refs = atomic_dec_return(&data->refs);
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WARN_ON(refs < 0);
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if (!refs) {
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spin_lock(&call_function.lock);
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list_del_rcu(&data->csd.list);
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spin_unlock(&call_function.lock);
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}
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if (refs)
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continue;
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csd_unlock(&data->csd);
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}
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put_cpu();
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}
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/*
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* Invoked by arch to handle an IPI for call function single. Must be
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* called from the arch with interrupts disabled.
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*/
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void generic_smp_call_function_single_interrupt(void)
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{
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struct call_single_queue *q = &__get_cpu_var(call_single_queue);
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unsigned int data_flags;
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LIST_HEAD(list);
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/*
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* Shouldn't receive this interrupt on a cpu that is not yet online.
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*/
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WARN_ON_ONCE(!cpu_online(smp_processor_id()));
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spin_lock(&q->lock);
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list_replace_init(&q->list, &list);
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spin_unlock(&q->lock);
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while (!list_empty(&list)) {
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struct call_single_data *data;
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data = list_entry(list.next, struct call_single_data, list);
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list_del(&data->list);
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/*
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* 'data' can be invalid after this call if flags == 0
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* (when called through generic_exec_single()),
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* so save them away before making the call:
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*/
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data_flags = data->flags;
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data->func(data->info);
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/*
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* Unlocked CSDs are valid through generic_exec_single():
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*/
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if (data_flags & CSD_FLAG_LOCK)
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csd_unlock(data);
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}
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}
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static DEFINE_PER_CPU(struct call_single_data, csd_data);
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/*
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* smp_call_function_single - Run a function on a specific CPU
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* @func: The function to run. This must be fast and non-blocking.
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* @info: An arbitrary pointer to pass to the function.
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* @wait: If true, wait until function has completed on other CPUs.
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*
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* Returns 0 on success, else a negative status code.
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*/
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int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
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int wait)
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{
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struct call_single_data d = {
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.flags = 0,
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};
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unsigned long flags;
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int this_cpu;
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int err = 0;
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/*
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* prevent preemption and reschedule on another processor,
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* as well as CPU removal
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*/
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this_cpu = get_cpu();
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/*
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* Can deadlock when called with interrupts disabled.
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* We allow cpu's that are not yet online though, as no one else can
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* send smp call function interrupt to this cpu and as such deadlocks
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* can't happen.
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*/
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WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
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&& !oops_in_progress);
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if (cpu == this_cpu) {
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local_irq_save(flags);
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func(info);
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local_irq_restore(flags);
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} else {
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if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
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struct call_single_data *data = &d;
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if (!wait)
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data = &__get_cpu_var(csd_data);
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csd_lock(data);
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data->func = func;
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data->info = info;
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generic_exec_single(cpu, data, wait);
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} else {
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err = -ENXIO; /* CPU not online */
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}
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}
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put_cpu();
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return err;
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}
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EXPORT_SYMBOL(smp_call_function_single);
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/*
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* smp_call_function_any - Run a function on any of the given cpus
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* @mask: The mask of cpus it can run on.
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* @func: The function to run. This must be fast and non-blocking.
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* @info: An arbitrary pointer to pass to the function.
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* @wait: If true, wait until function has completed.
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*
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* Returns 0 on success, else a negative status code (if no cpus were online).
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* Note that @wait will be implicitly turned on in case of allocation failures,
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* since we fall back to on-stack allocation.
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*
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* Selection preference:
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* 1) current cpu if in @mask
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* 2) any cpu of current node if in @mask
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* 3) any other online cpu in @mask
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*/
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int smp_call_function_any(const struct cpumask *mask,
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void (*func)(void *info), void *info, int wait)
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{
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unsigned int cpu;
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const struct cpumask *nodemask;
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int ret;
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/* Try for same CPU (cheapest) */
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cpu = get_cpu();
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if (cpumask_test_cpu(cpu, mask))
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goto call;
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/* Try for same node. */
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nodemask = cpumask_of_node(cpu);
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for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids;
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cpu = cpumask_next_and(cpu, nodemask, mask)) {
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if (cpu_online(cpu))
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goto call;
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}
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/* Any online will do: smp_call_function_single handles nr_cpu_ids. */
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cpu = cpumask_any_and(mask, cpu_online_mask);
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call:
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ret = smp_call_function_single(cpu, func, info, wait);
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put_cpu();
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return ret;
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}
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EXPORT_SYMBOL_GPL(smp_call_function_any);
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/**
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* __smp_call_function_single(): Run a function on another CPU
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* @cpu: The CPU to run on.
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* @data: Pre-allocated and setup data structure
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*
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* Like smp_call_function_single(), but allow caller to pass in a
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* pre-allocated data structure. Useful for embedding @data inside
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* other structures, for instance.
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*/
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void __smp_call_function_single(int cpu, struct call_single_data *data,
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int wait)
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{
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csd_lock(data);
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/*
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* Can deadlock when called with interrupts disabled.
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* We allow cpu's that are not yet online though, as no one else can
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* send smp call function interrupt to this cpu and as such deadlocks
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* can't happen.
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*/
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WARN_ON_ONCE(cpu_online(smp_processor_id()) && wait && irqs_disabled()
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&& !oops_in_progress);
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generic_exec_single(cpu, data, wait);
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}
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/**
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* smp_call_function_many(): Run a function on a set of other CPUs.
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* @mask: The set of cpus to run on (only runs on online subset).
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* @func: The function to run. This must be fast and non-blocking.
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* @info: An arbitrary pointer to pass to the function.
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* @wait: If true, wait (atomically) until function has completed
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* on other CPUs.
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*
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* If @wait is true, then returns once @func has returned.
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*
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* You must not call this function with disabled interrupts or from a
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* hardware interrupt handler or from a bottom half handler. Preemption
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* must be disabled when calling this function.
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*/
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void smp_call_function_many(const struct cpumask *mask,
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void (*func)(void *), void *info, bool wait)
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{
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struct call_function_data *data;
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unsigned long flags;
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int cpu, next_cpu, this_cpu = smp_processor_id();
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/*
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* Can deadlock when called with interrupts disabled.
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* We allow cpu's that are not yet online though, as no one else can
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* send smp call function interrupt to this cpu and as such deadlocks
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* can't happen.
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*/
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WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
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&& !oops_in_progress);
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/* So, what's a CPU they want? Ignoring this one. */
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cpu = cpumask_first_and(mask, cpu_online_mask);
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if (cpu == this_cpu)
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cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
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/* No online cpus? We're done. */
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if (cpu >= nr_cpu_ids)
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return;
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/* Do we have another CPU which isn't us? */
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next_cpu = cpumask_next_and(cpu, mask, cpu_online_mask);
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if (next_cpu == this_cpu)
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next_cpu = cpumask_next_and(next_cpu, mask, cpu_online_mask);
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/* Fastpath: do that cpu by itself. */
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if (next_cpu >= nr_cpu_ids) {
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smp_call_function_single(cpu, func, info, wait);
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return;
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}
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data = &__get_cpu_var(cfd_data);
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csd_lock(&data->csd);
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data->csd.func = func;
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data->csd.info = info;
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cpumask_and(data->cpumask, mask, cpu_online_mask);
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cpumask_clear_cpu(this_cpu, data->cpumask);
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atomic_set(&data->refs, cpumask_weight(data->cpumask));
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spin_lock_irqsave(&call_function.lock, flags);
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/*
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* Place entry at the _HEAD_ of the list, so that any cpu still
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* observing the entry in generic_smp_call_function_interrupt()
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* will not miss any other list entries:
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*/
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list_add_rcu(&data->csd.list, &call_function.queue);
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spin_unlock_irqrestore(&call_function.lock, flags);
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/*
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* Make the list addition visible before sending the ipi.
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* (IPIs must obey or appear to obey normal Linux cache
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* coherency rules -- see comment in generic_exec_single).
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*/
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smp_mb();
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/* Send a message to all CPUs in the map */
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arch_send_call_function_ipi_mask(data->cpumask);
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/* Optionally wait for the CPUs to complete */
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if (wait)
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csd_lock_wait(&data->csd);
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}
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EXPORT_SYMBOL(smp_call_function_many);
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/**
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* smp_call_function(): Run a function on all other CPUs.
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* @func: The function to run. This must be fast and non-blocking.
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* @info: An arbitrary pointer to pass to the function.
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* @wait: If true, wait (atomically) until function has completed
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* on other CPUs.
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*
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* Returns 0.
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*
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* If @wait is true, then returns once @func has returned; otherwise
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* it returns just before the target cpu calls @func.
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*
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* You must not call this function with disabled interrupts or from a
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* hardware interrupt handler or from a bottom half handler.
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*/
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int smp_call_function(void (*func)(void *), void *info, int wait)
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{
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preempt_disable();
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smp_call_function_many(cpu_online_mask, func, info, wait);
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preempt_enable();
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return 0;
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}
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EXPORT_SYMBOL(smp_call_function);
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void ipi_call_lock(void)
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{
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spin_lock(&call_function.lock);
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}
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void ipi_call_unlock(void)
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{
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spin_unlock(&call_function.lock);
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}
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void ipi_call_lock_irq(void)
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{
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spin_lock_irq(&call_function.lock);
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}
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void ipi_call_unlock_irq(void)
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{
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spin_unlock_irq(&call_function.lock);
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}
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