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 /* For !GENERIC_IRQ_EFFECTIVE_AFF_MASK this looks at general affinity mask */
  18 static inline bool irq_needs_fixup(struct irq_data *d)
  19 {
  20         const struct cpumask *m = irq_data_get_effective_affinity_mask(d);
  21
  22         return cpumask_test_cpu(smp_processor_id(), m);
  23 }
  24
  25 static bool migrate_one_irq(struct irq_desc *desc)
  26 {
  27         struct irq_data *d = irq_desc_get_irq_data(desc);
  28         struct irq_chip *chip = irq_data_get_irq_chip(d);
  29         bool maskchip = !irq_can_move_pcntxt(d) && !irqd_irq_masked(d);
  30         const struct cpumask *affinity;
  31         bool brokeaff = false;
  32         int err;
  33
  34         /*
  35          * IRQ chip might be already torn down, but the irq descriptor is
  36          * still in the radix tree. Also if the chip has no affinity setter,
  37          * nothing can be done here.
  38          */
  39         if (!chip || !chip->irq_set_affinity) {
  40                 pr_debug("IRQ %u: Unable to migrate away\n", d->irq);
  41                 return false;
  42         }
  43
  44         /*
  45          * No move required, if:
  46          * - Interrupt is per cpu
  47          * - Interrupt is not started
  48          * - Affinity mask does not include this CPU.
  49          *
  50          * Note: Do not check desc->action as this might be a chained
  51          * interrupt.
  52          */
  53         if (irqd_is_per_cpu(d) || !irqd_is_started(d) || !irq_needs_fixup(d)) {
  54                 /*
  55                  * If an irq move is pending, abort it if the dying CPU is
  56                  * the sole target.
  57                  */
  58                 irq_fixup_move_pending(desc, false);
  59                 return false;
  60         }
  61
  62         /*
  63          * Complete an eventually pending irq move cleanup. If this
  64          * interrupt was moved in hard irq context, then the vectors need
  65          * to be cleaned up. It can't wait until this interrupt actually
  66          * happens and this CPU was involved.
  67          */
  68         irq_force_complete_move(desc);
  69
  70         /*
  71          * If there is a setaffinity pending, then try to reuse the pending
  72          * mask, so the last change of the affinity does not get lost. If
  73          * there is no move pending or the pending mask does not contain
  74          * any online CPU, use the current affinity mask.
  75          */
  76         if (irq_fixup_move_pending(desc, true))
  77                 affinity = irq_desc_get_pending_mask(desc);
  78         else
  79                 affinity = irq_data_get_affinity_mask(d);
  80
  81         /* Mask the chip for interrupts which cannot move in process context */
  82         if (maskchip && chip->irq_mask)
  83                 chip->irq_mask(d);
  84
  85         if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) {
  86                 /*
  87                  * If the interrupt is managed, then shut it down and leave
  88                  * the affinity untouched.
  89                  */
  90                 if (irqd_affinity_is_managed(d)) {
  91                         irqd_set_managed_shutdown(d);
  92                         irq_shutdown(desc);
  93                         return false;
  94                 }
  95                 affinity = cpu_online_mask;
  96                 brokeaff = true;
  97         }
  98
  99         err = irq_do_set_affinity(d, affinity, true);
 100         if (err) {
 101                 pr_warn_ratelimited("IRQ%u: set affinity failed(%d).\n",
 102                                     d->irq, err);
 103                 brokeaff = false;
 104         }
 105
 106         if (maskchip && chip->irq_unmask)
 107                 chip->irq_unmask(d);
 108
 109         return brokeaff;
 110 }
 111
 112 /**
 113  * irq_migrate_all_off_this_cpu - Migrate irqs away from offline cpu
 114  *
 115  * The current CPU has been marked offline.  Migrate IRQs off this CPU.
 116  * If the affinity settings do not allow other CPUs, force them onto any
 117  * available CPU.
 118  *
 119  * Note: we must iterate over all IRQs, whether they have an attached
 120  * action structure or not, as we need to get chained interrupts too.
 121  */
 122 void irq_migrate_all_off_this_cpu(void)
 123 {
 124         struct irq_desc *desc;
 125         unsigned int irq;
 126
 127         for_each_active_irq(irq) {
 128                 bool affinity_broken;
 129
 130                 desc = irq_to_desc(irq);
 131                 raw_spin_lock(&desc->lock);
 132                 affinity_broken = migrate_one_irq(desc);
 133                 raw_spin_unlock(&desc->lock);
 134
 135                 if (affinity_broken) {
 136                         pr_warn_ratelimited("IRQ %u: no longer affine to CPU%u\n",
 137                                             irq, smp_processor_id());
 138                 }
 139         }
 140 }
 141
 142 static void irq_restore_affinity_of_irq(struct irq_desc *desc, unsigned int cpu)
 143 {
 144         struct irq_data *data = irq_desc_get_irq_data(desc);
 145         const struct cpumask *affinity = irq_data_get_affinity_mask(data);
 146
 147         if (!irqd_affinity_is_managed(data) || !desc->action ||
 148             !irq_data_get_irq_chip(data) || !cpumask_test_cpu(cpu, affinity))
 149                 return;
 150
 151         if (irqd_is_managed_and_shutdown(data)) {
 152                 irq_startup(desc, IRQ_RESEND, IRQ_START_COND);
 153                 return;
 154         }
 155
 156         /*
 157          * If the interrupt can only be directed to a single target
 158          * CPU then it is already assigned to a CPU in the affinity
 159          * mask. No point in trying to move it around.
 160          */
 161         if (!irqd_is_single_target(data))
 162                 irq_set_affinity_locked(data, affinity, false);
 163 }
 164
 165 /**
 166  * irq_affinity_online_cpu - Restore affinity for managed interrupts
 167  * @cpu:        Upcoming CPU for which interrupts should be restored
 168  */
 169 int irq_affinity_online_cpu(unsigned int cpu)
 170 {
 171         struct irq_desc *desc;
 172         unsigned int irq;
 173
 174         irq_lock_sparse();
 175         for_each_active_irq(irq) {
 176                 desc = irq_to_desc(irq);
 177                 raw_spin_lock_irq(&desc->lock);
 178                 irq_restore_affinity_of_irq(desc, cpu);
 179                 raw_spin_unlock_irq(&desc->lock);
 180         }
 181         irq_unlock_sparse();
 182
 183         return 0;
 184 }