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
  17 static 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  */
  60 void 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 }