Commit 1b5ba350 authored by Dietmar Eggemann's avatar Dietmar Eggemann Committed by Russell King
Browse files

ARM: 8824/1: fix a migrating irq bug when hotplug cpu 



Arm TC2 fails cpu hotplug stress test.

This issue was tracked down to a missing copy of the new affinity
cpumask for the vexpress-spc interrupt into struct
irq_common_data.affinity when the interrupt is migrated in
migrate_one_irq().

Fix it by replacing the arm specific hotplug cpu migration with the
generic irq code.

This is the counterpart implementation to commit 217d453d ("arm64:
fix a migrating irq bug when hotplug cpu").

Tested with cpu hotplug stress test on Arm TC2 (multi_v7_defconfig plus
CONFIG_ARM_BIG_LITTLE_CPUFREQ=y and CONFIG_ARM_VEXPRESS_SPC_CPUFREQ=y).
The vexpress-spc interrupt (irq=22) on this board is affine to CPU0.
Its affinity cpumask now changes correctly e.g. from 0 to 1-4 when
CPU0 is hotplugged out.

Suggested-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarDietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Reviewed-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
parent bfeffd15

arch/arm/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -1400,6 +1400,7 @@ config NR_CPUS 
config HOTPLUG_CPU

	bool "Support for hot-pluggable CPUs"

	depends on SMP

	select GENERIC_IRQ_MIGRATION

	help

	  Say Y here to experiment with turning CPUs off and on.  CPUs

	  can be controlled through /sys/devices/system/cpu.

arch/arm/include/asm/irq.h

+0 −1
Original line number Diff line number Diff line
@@ -25,7 +25,6 @@ 
#ifndef __ASSEMBLY__

struct irqaction;

struct pt_regs;

extern void migrate_irqs(void);



extern void asm_do_IRQ(unsigned int, struct pt_regs *);

void handle_IRQ(unsigned int, struct pt_regs *);

arch/arm/kernel/irq.c

+0 −62
Original line number Diff line number Diff line
@@ -31,7 +31,6 @@ 
#include <linux/smp.h>

#include <linux/init.h>

#include <linux/seq_file.h>

#include <linux/ratelimit.h>

#include <linux/errno.h>

#include <linux/list.h>

#include <linux/kallsyms.h>
@@ -109,64 +108,3 @@ int __init arch_probe_nr_irqs(void) 
	return nr_irqs;

}

#endif
 


#ifdef CONFIG_HOTPLUG_CPU

static bool migrate_one_irq(struct irq_desc *desc)

{

	struct irq_data *d = irq_desc_get_irq_data(desc);

	const struct cpumask *affinity = irq_data_get_affinity_mask(d);

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

	else if (c->irq_set_affinity(d, affinity, false) == IRQ_SET_MASK_OK && ret)

		cpumask_copy(irq_data_get_affinity_mask(d), affinity);



	return ret;

}



/*

 * 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 migrate_irqs(void)

{

	unsigned int i;

	struct irq_desc *desc;

	unsigned long flags;



	local_irq_save(flags);



	for_each_irq_desc(i, desc) {

		bool affinity_broken;



		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",

				i, smp_processor_id());

	}



	local_irq_restore(flags);

}

#endif /* CONFIG_HOTPLUG_CPU */

arch/arm/kernel/smp.c

+1 −1
Original line number Diff line number Diff line
@@ -254,7 +254,7 @@ int __cpu_disable(void) 
	/*

	 * OK - migrate IRQs away from this CPU

	 */

	migrate_irqs();

	irq_migrate_all_off_this_cpu();



	/*

	 * Flush user cache and TLB mappings, and then remove this CPU

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