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