1 files changed, 70 insertions, 0 deletions

diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index 884d875c1434..dbb60878b744 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -266,6 +266,76 @@ __visible void smp_trace_x86_platform_ipi(struct pt_regs *regs)
 EXPORT_SYMBOL_GPL(vector_used_by_percpu_irq);
 
 #ifdef CONFIG_HOTPLUG_CPU
+/*
+ * This cpu is going to be removed and its vectors migrated to the remaining
+ * online cpus.  Check to see if there are enough vectors in the remaining cpus.
+ * This function is protected by stop_machine().
+ */
+int check_irq_vectors_for_cpu_disable(void)
+{
+        int irq, cpu;
+        unsigned int this_cpu, vector, this_count, count;
+        struct irq_desc *desc;
+        struct irq_data *data;
+        struct cpumask affinity_new, online_new;
+
+        this_cpu = smp_processor_id();
+        cpumask_copy(&online_new, cpu_online_mask);
+        cpu_clear(this_cpu, online_new);
+
+        this_count = 0;
+        for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) {
+                irq = __this_cpu_read(vector_irq[vector]);
+                if (irq >= 0) {
+                        desc = irq_to_desc(irq);
+                        data = irq_desc_get_irq_data(desc);
+                        cpumask_copy(&affinity_new, data->affinity);
+                        cpu_clear(this_cpu, affinity_new);
+
+                        /* Do not count inactive or per-cpu irqs. */
+                        if (!irq_has_action(irq) || irqd_is_per_cpu(data))
+                                continue;
+
+                        /*
+                         * A single irq may be mapped to multiple
+                         * cpu's vector_irq[] (for example IOAPIC cluster
+                         * mode).  In this case we have two
+                         * possibilities:
+                         *
+                         * 1) the resulting affinity mask is empty; that is
+                         * this the down'd cpu is the last cpu in the irq's
+                         * affinity mask, or
+                         *
+                         * 2) the resulting affinity mask is no longer
+                         * a subset of the online cpus but the affinity
+                         * mask is not zero; that is the down'd cpu is the
+                         * last online cpu in a user set affinity mask.
+                         */
+                        if (cpumask_empty(&affinity_new) ||
+                            !cpumask_subset(&affinity_new, &online_new))
+                                this_count++;
+                }
+        }
+
+        count = 0;
+        for_each_online_cpu(cpu) {
+                if (cpu == this_cpu)
+                        continue;
+                for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS;
+                     vector++) {
+                        if (per_cpu(vector_irq, cpu)[vector] < 0)
+                                count++;
+                }
+        }
+
+        if (count < this_count) {
+                pr_warn("CPU %d disable failed: CPU has %u vectors assigned and there are only %u available.\n",
+                        this_cpu, this_count, count);
+                return -ERANGE;
+        }
+        return 0;
+}
+
 /* A cpu has been removed from cpu_online_mask.  Reset irq affinities. */
 void fixup_irqs(void)
 {