LXR linux/kernel/irq/cpuhotplug.c

   1/*
   2 * Generic cpu hotunplug interrupt migration code copied from the
   3 * arch/arm implementation
   4 *
   5 * Copyright (C) Russell King
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License version 2 as
   9 * published by the Free Software Foundation.
  10 */
  11#include <linux/interrupt.h>
  12#include <linux/ratelimit.h>
  13#include <linux/irq.h>
  14
  15#include "internals.h"
  16
  17static bool migrate_one_irq(struct irq_desc *desc)
  18{
  19        struct irq_data *d = irq_desc_get_irq_data(desc);
  20        const struct cpumask *affinity = d->common->affinity;
  21        struct irq_chip *c;
  22        bool ret = false;
  23
  24        /*
  25         * If this is a per-CPU interrupt, or the affinity does not
  26         * include this CPU, then we have nothing to do.
  27         */
  28        if (irqd_is_per_cpu(d) ||
  29            !cpumask_test_cpu(smp_processor_id(), affinity))
  30                return false;
  31
  32        if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) {
  33                affinity = cpu_online_mask;
  34                ret = true;
  35        }
  36
  37        c = irq_data_get_irq_chip(d);
  38        if (!c->irq_set_affinity) {
  39                pr_debug("IRQ%u: unable to set affinity\n", d->irq);
  40        } else {
  41                int r = irq_do_set_affinity(d, affinity, false);
  42                if (r)
  43                        pr_warn_ratelimited("IRQ%u: set affinity failed(%d).\n",
  44                                            d->irq, r);
  45        }
  46
  47        return ret;
  48}
  49
  50/**
  51 * irq_migrate_all_off_this_cpu - Migrate irqs away from offline cpu
  52 *
  53 * The current CPU has been marked offline.  Migrate IRQs off this CPU.
  54 * If the affinity settings do not allow other CPUs, force them onto any
  55 * available CPU.
  56 *
  57 * Note: we must iterate over all IRQs, whether they have an attached
  58 * action structure or not, as we need to get chained interrupts too.
  59 */
  60void irq_migrate_all_off_this_cpu(void)
  61{
  62        unsigned int irq;
  63        struct irq_desc *desc;
  64        unsigned long flags;
  65
  66        local_irq_save(flags);
  67
  68        for_each_active_irq(irq) {
  69                bool affinity_broken;
  70
  71                desc = irq_to_desc(irq);
  72                raw_spin_lock(&desc->lock);
  73                affinity_broken = migrate_one_irq(desc);
  74                raw_spin_unlock(&desc->lock);
  75
  76                if (affinity_broken)
  77                        pr_warn_ratelimited("IRQ%u no longer affine to CPU%u\n",
  78                                            irq, smp_processor_id());
  79        }
  80
  81        local_irq_restore(flags);
  82}
  83