Commit f1e0bb0a authored by Yang Yingliang's avatar Yang Yingliang Committed by Thomas Gleixner
Browse files

genirq: Introduce generic irq migration for cpu hotunplug 



ARM and ARM64 have almost identical code for migrating interrupts on
cpu hotunplug. Provide a generic version which can be used by both.

The new code addresses a shortcoming in the ARM[64] variants which
fails to update the affinity change in some cases. The solution for
this is to use the core function irq_do_set_affinity() instead of open
coding it.

[ tglx: Added copyright notice and license boilerplate. Rewrote
  	subject and changelog. ]

Signed-off-by: default avatarYang Yingliang <yangyingliang@huawei.com>
Acked-by: default avatarRussell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Hanjun Guo <hanjun.guo@linaro.org>
Cc: <linux-arm-kernel@lists.infradead.org>
Link: http://lkml.kernel.org/r/1443087135-17044-2-git-send-email-yangyingliang@huawei.com


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 9ffecb10

include/linux/irq.h

+2 −0
Original line number Diff line number Diff line
@@ -452,6 +452,8 @@ extern int irq_set_affinity_locked(struct irq_data *data, 
				   const struct cpumask *cpumask, bool force);

extern int irq_set_vcpu_affinity(unsigned int irq, void *vcpu_info);



extern void irq_migrate_all_off_this_cpu(void);



#if defined(CONFIG_SMP) && defined(CONFIG_GENERIC_PENDING_IRQ)

void irq_move_irq(struct irq_data *data);

void irq_move_masked_irq(struct irq_data *data);

kernel/irq/Kconfig

+4 −0
Original line number Diff line number Diff line
@@ -30,6 +30,10 @@ config GENERIC_IRQ_LEGACY_ALLOC_HWIRQ 
config GENERIC_PENDING_IRQ

	bool



# Support for generic irq migrating off cpu before the cpu is offline.

config GENERIC_IRQ_MIGRATION

	bool



# Alpha specific irq affinity mechanism

config AUTO_IRQ_AFFINITY

       bool

kernel/irq/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -5,5 +5,6 @@ obj-$(CONFIG_GENERIC_IRQ_PROBE) += autoprobe.o 
obj-$(CONFIG_IRQ_DOMAIN) += irqdomain.o

obj-$(CONFIG_PROC_FS) += proc.o

obj-$(CONFIG_GENERIC_PENDING_IRQ) += migration.o

obj-$(CONFIG_GENERIC_IRQ_MIGRATION) += cpuhotplug.o

obj-$(CONFIG_PM_SLEEP) += pm.o

obj-$(CONFIG_GENERIC_MSI_IRQ) += msi.o

kernel/irq/cpuhotplug.c

0 → 100644
+82 −0
Original line number Diff line number Diff line 
/*

 * 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 "internals.h"



static bool migrate_one_irq(struct irq_desc *desc)

{

	struct irq_data *d = irq_desc_get_irq_data(desc);

	const struct cpumask *affinity = d->common->affinity;

	struct irq_chip *c;

	bool ret = false;



	/*

	 * If this is a per-CPU interrupt, or the affinity does not

	 * include this CPU, then we have nothing to do.

	 */

	if (irqd_is_per_cpu(d) ||

	    !cpumask_test_cpu(smp_processor_id(), affinity))

		return false;



	if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) {

		affinity = cpu_online_mask;

		ret = true;

	}



	c = irq_data_get_irq_chip(d);

	if (!c->irq_set_affinity) {

		pr_warn_ratelimited("IRQ%u: unable to set affinity\n", d->irq);

	} else {

		int r = irq_do_set_affinity(d, affinity, false);

		if (r)

			pr_warn_ratelimited("IRQ%u: set affinity failed(%d).\n",

					    d->irq, r);

	}



	return ret;

}



/**

 * 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)

{

	unsigned int irq;

	struct irq_desc *desc;

	unsigned long flags;



	local_irq_save(flags);



	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());

	}



	local_irq_restore(flags);

}

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