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: Yang Yingliang <yangyingliang@huawei.com>
Acked-by: Russell 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: Thomas Gleixner <tglx@linutronix.de>

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 11bf092..45cc729 100644 (file)
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -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);

diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig
index 9a76e3b..3b48dab 100644 (file)
--- a/kernel/irq/Kconfig
+++ b/kernel/irq/Kconfig
@@ -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

diff --git a/kernel/irq/Makefile b/kernel/irq/Makefile
index d121235..2fc9cbd 100644 (file)
--- a/kernel/irq/Makefile
+++ b/kernel/irq/Makefile
@@ -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

diff --git a/kernel/irq/cpuhotplug.c b/kernel/irq/cpuhotplug.c
new file mode 100644 (file)
index 0000000..80f4f4e
--- /dev/null
+++ b/kernel/irq/cpuhotplug.c
@@ -0,0 +1,82 @@
+/*
+ * 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);
+}