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 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>

4 files changed, 2 insertions, 64 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 664e918e2624..26524b75970a 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -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.
diff --git a/arch/arm/include/asm/irq.h b/arch/arm/include/asm/irq.h
index c883fcbe93b6..46d41140df27 100644
--- a/arch/arm/include/asm/irq.h
+++ b/arch/arm/include/asm/irq.h
@@ -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 *);
diff --git a/arch/arm/kernel/irq.c b/arch/arm/kernel/irq.c
index 9908dacf9229..844861368cd5 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>
@@ -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 */
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 3bf82232b1be..1d6f5ea522f4 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -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