// SPDX-License-Identifier: GPL-2.0
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/*
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* Generic cpu hotunplug interrupt migration code copied from the
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* arch/arm implementation
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*
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* Copyright (C) Russell King
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/interrupt.h>
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#include <linux/ratelimit.h>
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#include <linux/irq.h>
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#include <linux/sched/isolation.h>
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#include "internals.h"
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/* For !GENERIC_IRQ_EFFECTIVE_AFF_MASK this looks at general affinity mask */
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static inline bool irq_needs_fixup(struct irq_data *d)
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{
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const struct cpumask *m = irq_data_get_effective_affinity_mask(d);
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unsigned int cpu = smp_processor_id();
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#ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK
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/*
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* The cpumask_empty() check is a workaround for interrupt chips,
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* which do not implement effective affinity, but the architecture has
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* enabled the config switch. Use the general affinity mask instead.
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*/
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if (cpumask_empty(m))
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m = irq_data_get_affinity_mask(d);
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/*
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* Sanity check. If the mask is not empty when excluding the outgoing
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* CPU then it must contain at least one online CPU. The outgoing CPU
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* has been removed from the online mask already.
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*/
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if (cpumask_any_but(m, cpu) < nr_cpu_ids &&
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cpumask_any_and(m, cpu_online_mask) >= nr_cpu_ids) {
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/*
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* If this happens then there was a missed IRQ fixup at some
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* point. Warn about it and enforce fixup.
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*/
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pr_debug("Eff. affinity %*pbl of IRQ %u contains only offline CPUs after offlining CPU %u\n",
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cpumask_pr_args(m), d->irq, cpu);
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return true;
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}
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#endif
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return cpumask_test_cpu(cpu, m);
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}
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static bool migrate_one_irq(struct irq_desc *desc)
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{
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struct irq_data *d = irq_desc_get_irq_data(desc);
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struct irq_chip *chip = irq_data_get_irq_chip(d);
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bool maskchip = !irq_can_move_pcntxt(d) && !irqd_irq_masked(d);
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const struct cpumask *affinity;
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bool brokeaff = false;
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int err;
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/*
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* IRQ chip might be already torn down, but the irq descriptor is
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* still in the radix tree. Also if the chip has no affinity setter,
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* nothing can be done here.
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*/
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if (!chip || !chip->irq_set_affinity) {
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pr_debug("IRQ %u: Unable to migrate away\n", d->irq);
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return false;
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}
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/*
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* No move required, if:
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* - Interrupt is per cpu
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* - Interrupt is not started
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* - Affinity mask does not include this CPU.
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*
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* Note: Do not check desc->action as this might be a chained
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* interrupt.
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*/
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if (irqd_is_per_cpu(d) || !irqd_is_started(d) || !irq_needs_fixup(d)) {
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/*
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* If an irq move is pending, abort it if the dying CPU is
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* the sole target.
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*/
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irq_fixup_move_pending(desc, false);
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return false;
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}
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/*
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* Complete an eventually pending irq move cleanup. If this
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* interrupt was moved in hard irq context, then the vectors need
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* to be cleaned up. It can't wait until this interrupt actually
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* happens and this CPU was involved.
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*/
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irq_force_complete_move(desc);
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/*
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* If there is a setaffinity pending, then try to reuse the pending
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* mask, so the last change of the affinity does not get lost. If
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* there is no move pending or the pending mask does not contain
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* any online CPU, use the current affinity mask.
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*/
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if (irq_fixup_move_pending(desc, true))
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affinity = irq_desc_get_pending_mask(desc);
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else
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affinity = irq_data_get_affinity_mask(d);
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/* Mask the chip for interrupts which cannot move in process context */
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if (maskchip && chip->irq_mask)
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chip->irq_mask(d);
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if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) {
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/*
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* If the interrupt is managed, then shut it down and leave
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* the affinity untouched.
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*/
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if (irqd_affinity_is_managed(d)) {
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irqd_set_managed_shutdown(d);
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irq_shutdown_and_deactivate(desc);
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return false;
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}
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affinity = cpu_online_mask;
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brokeaff = true;
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}
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/*
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* Do not set the force argument of irq_do_set_affinity() as this
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* disables the masking of offline CPUs from the supplied affinity
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* mask and therefore might keep/reassign the irq to the outgoing
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* CPU.
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*/
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err = irq_do_set_affinity(d, affinity, false);
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if (err) {
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pr_warn_ratelimited("IRQ%u: set affinity failed(%d).\n",
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d->irq, err);
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brokeaff = false;
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}
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if (maskchip && chip->irq_unmask)
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chip->irq_unmask(d);
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return brokeaff;
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}
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/**
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* irq_migrate_all_off_this_cpu - Migrate irqs away from offline cpu
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*
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* The current CPU has been marked offline. Migrate IRQs off this CPU.
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* If the affinity settings do not allow other CPUs, force them onto any
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* available CPU.
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*
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* Note: we must iterate over all IRQs, whether they have an attached
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* action structure or not, as we need to get chained interrupts too.
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*/
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void irq_migrate_all_off_this_cpu(void)
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{
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struct irq_desc *desc;
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unsigned int irq;
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for_each_active_irq(irq) {
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bool affinity_broken;
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desc = irq_to_desc(irq);
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raw_spin_lock(&desc->lock);
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affinity_broken = migrate_one_irq(desc);
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raw_spin_unlock(&desc->lock);
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if (affinity_broken) {
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pr_debug_ratelimited("IRQ %u: no longer affine to CPU%u\n",
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irq, smp_processor_id());
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}
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}
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}
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static bool hk_should_isolate(struct irq_data *data, unsigned int cpu)
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{
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const struct cpumask *hk_mask;
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if (!housekeeping_enabled(HK_FLAG_MANAGED_IRQ))
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return false;
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hk_mask = housekeeping_cpumask(HK_FLAG_MANAGED_IRQ);
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if (cpumask_subset(irq_data_get_effective_affinity_mask(data), hk_mask))
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return false;
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return cpumask_test_cpu(cpu, hk_mask);
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}
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static void irq_restore_affinity_of_irq(struct irq_desc *desc, unsigned int cpu)
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{
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struct irq_data *data = irq_desc_get_irq_data(desc);
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const struct cpumask *affinity = irq_data_get_affinity_mask(data);
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if (!irqd_affinity_is_managed(data) || !desc->action ||
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!irq_data_get_irq_chip(data) || !cpumask_test_cpu(cpu, affinity))
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return;
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if (irqd_is_managed_and_shutdown(data)) {
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irq_startup(desc, IRQ_RESEND, IRQ_START_COND);
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return;
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}
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/*
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* If the interrupt can only be directed to a single target
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* CPU then it is already assigned to a CPU in the affinity
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* mask. No point in trying to move it around unless the
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* isolation mechanism requests to move it to an upcoming
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* housekeeping CPU.
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*/
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if (!irqd_is_single_target(data) || hk_should_isolate(data, cpu))
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irq_set_affinity_locked(data, affinity, false);
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}
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/**
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* irq_affinity_online_cpu - Restore affinity for managed interrupts
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* @cpu: Upcoming CPU for which interrupts should be restored
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*/
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int irq_affinity_online_cpu(unsigned int cpu)
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{
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struct irq_desc *desc;
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unsigned int irq;
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irq_lock_sparse();
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for_each_active_irq(irq) {
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desc = irq_to_desc(irq);
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raw_spin_lock_irq(&desc->lock);
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irq_restore_affinity_of_irq(desc, cpu);
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raw_spin_unlock_irq(&desc->lock);
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}
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irq_unlock_sparse();
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return 0;
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}
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