971af7d6ed
Userspace can set the default IRQ affinity setting by writing into /proc/irq/default_smp_affinity file. When an IRQ affinity is broken during isolation/hotplug,override the affinity to online and un-isolated CPUs from the default affinity CPUs. If no such CPU is available, then only override with cpu_online_mask. Change-Id: I7578728ed0d7c17c5890d9916cfd6451d1968568 Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
116 lines
3.2 KiB
C
116 lines
3.2 KiB
C
/*
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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/cpumask.h>
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#include "internals.h"
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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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const struct cpumask *affinity = d->common->affinity;
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struct irq_chip *c;
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bool ret = false;
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struct cpumask available_cpus;
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/*
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* If this is a per-CPU interrupt, or the affinity does not
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* include this CPU, then we have nothing to do.
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*/
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if (irqd_is_per_cpu(d) ||
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!cpumask_test_cpu(smp_processor_id(), affinity))
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return false;
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cpumask_copy(&available_cpus, affinity);
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cpumask_andnot(&available_cpus, &available_cpus, cpu_isolated_mask);
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affinity = &available_cpus;
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if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) {
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/*
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* The order of preference for selecting a fallback CPU is
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*
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* (1) online and un-isolated CPU from default affinity
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* (2) online and un-isolated CPU
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* (3) online CPU
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*/
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cpumask_andnot(&available_cpus, cpu_online_mask,
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cpu_isolated_mask);
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if (cpumask_intersects(&available_cpus, irq_default_affinity))
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cpumask_and(&available_cpus, &available_cpus,
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irq_default_affinity);
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else if (cpumask_empty(&available_cpus))
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affinity = cpu_online_mask;
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/*
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* We are overriding the affinity with all online and
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* un-isolated cpus. irq_set_affinity_locked() call
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* below notify this mask to PM QOS affinity listener.
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* That results in applying the CPU_DMA_LATENCY QOS
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* to all the CPUs specified in the mask. But the low
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* level irqchip driver sets the affinity of an irq
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* to only one CPU. So pick only one CPU from the
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* prepared mask while overriding the user affinity.
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*/
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affinity = cpumask_of(cpumask_any(affinity));
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ret = true;
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}
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c = irq_data_get_irq_chip(d);
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if (!c->irq_set_affinity) {
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pr_debug("IRQ%u: unable to set affinity\n", d->irq);
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} else {
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int r = irq_set_affinity_locked(d, affinity, false);
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if (r)
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pr_warn_ratelimited("IRQ%u: set affinity failed(%d).\n",
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d->irq, r);
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}
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return ret;
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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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unsigned int irq;
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struct irq_desc *desc;
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unsigned long flags;
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local_irq_save(flags);
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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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if (!desc)
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continue;
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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_warn_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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local_irq_restore(flags);
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}
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