1 files changed, 116 insertions, 0 deletions
diff --git a/kernel/irq/cpuhotplug.c b/kernel/irq/cpuhotplug.c
new file mode 100644
index 000000000000..4684b7595e63
--- /dev/null
+++ b/kernel/irq/cpuhotplug.c
@@ -0,0 +1,116 @@
+/*
+ * 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 <linux/cpumask.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;
+	struct cpumask available_cpus;
+
+	/*
+	 * 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;
+
+	cpumask_copy(&available_cpus, affinity);
+	cpumask_andnot(&available_cpus, &available_cpus, cpu_isolated_mask);
+	affinity = &available_cpus;
+
+	if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) {
+		/*
+		 * The order of preference for selecting a fallback CPU is
+		 *
+		 * (1) online and un-isolated CPU from default affinity
+		 * (2) online and un-isolated CPU
+		 * (3) online CPU
+		 */
+		cpumask_andnot(&available_cpus, cpu_online_mask,
+							cpu_isolated_mask);
+		if (cpumask_intersects(&available_cpus, irq_default_affinity))
+			cpumask_and(&available_cpus, &available_cpus,
+							irq_default_affinity);
+		else if (cpumask_empty(&available_cpus))
+			affinity = cpu_online_mask;
+
+		/*
+		 * We are overriding the affinity with all online and
+		 * un-isolated cpus. irq_set_affinity_locked() call
+		 * below notify this mask to PM QOS affinity listener.
+		 * That results in applying the CPU_DMA_LATENCY QOS
+		 * to all the CPUs specified in the mask. But the low
+		 * level irqchip driver sets the affinity of an irq
+		 * to only one CPU. So pick only one CPU from the
+		 * prepared mask while overriding the user affinity.
+		 */
+		affinity = cpumask_of(cpumask_any(affinity));
+		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 {
+		int r = irq_set_affinity_locked(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);
+		if (!desc)
+			continue;
+
+		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);
+}