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    Subject[PATCH 4.9 022/118] ARM: 8824/1: fix a migrating irq bug when hotplug cpu
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    [ Upstream commit 1b5ba350784242eb1f899bcffd95d2c7cff61e84 ]

    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 217d453d473c ("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: Marc Zyngier <marc.zyngier@arm.com>
    Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
    Acked-by: Marc Zyngier <marc.zyngier@arm.com>
    Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
    Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/arm/Kconfig | 1 +
    arch/arm/include/asm/irq.h | 1 -
    arch/arm/kernel/irq.c | 62 --------------------------------------
    arch/arm/kernel/smp.c | 2 +-
    4 files changed, 2 insertions(+), 64 deletions(-)

    diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
    index b5d529fdffab..74a70f91b01a 100644
    --- a/arch/arm/Kconfig
    +++ b/arch/arm/Kconfig
    @@ -1457,6 +1457,7 @@ 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.
    diff --git a/arch/arm/include/asm/irq.h b/arch/arm/include/asm/irq.h
    index e53638c8ed8a..61e1d089ce1a 100644
    --- a/arch/arm/include/asm/irq.h
    +++ b/arch/arm/include/asm/irq.h
    @@ -24,7 +24,6 @@
    #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 *);
    diff --git a/arch/arm/kernel/irq.c b/arch/arm/kernel/irq.c
    index ece04a457486..5b07c7a31c31 100644
    --- a/arch/arm/kernel/irq.c
    +++ b/arch/arm/kernel/irq.c
    @@ -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>
    @@ -119,64 +118,3 @@ 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 */
    diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
    index 8faf869e9fb2..bc83ec7ed53f 100644
    --- a/arch/arm/kernel/smp.c
    +++ b/arch/arm/kernel/smp.c
    @@ -253,7 +253,7 @@ 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
    --
    2.19.1


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