Merge branches 'core-urgent-for-linus' and 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull rcu fix and x86 irq fix from Ingo Molnar:

 - Fix a bug that caused an RCU warning splat.

 - Two x86 irq related fixes: a hotplug crash fix and an ACPI IRQ
   registry fix.

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rcu: Clear need_qs flag to prevent splat

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/irq: Check for valid irq descriptor in check_irq_vectors_for_cpu_disable()
  x86/irq: Fix regression caused by commit b568b8601f05

arch/x86/kernel/acpi/boot.c

@@ -613,6 +613,11 @@ int acpi_gsi_to_irq(u32 gsi, unsigned int *irqp)
 {
 	int rc, irq, trigger, polarity;
 
+	if (acpi_irq_model == ACPI_IRQ_MODEL_PIC) {
+		*irqp = gsi;
+		return 0;
+	}
+
 	rc = acpi_get_override_irq(gsi, &trigger, &polarity);
 	if (rc == 0) {
 		trigger = trigger ? ACPI_LEVEL_SENSITIVE : ACPI_EDGE_SENSITIVE;

arch/x86/kernel/irq.c

@@ -302,6 +302,9 @@ int check_irq_vectors_for_cpu_disable(void)
 		irq = __this_cpu_read(vector_irq[vector]);
 		if (irq >= 0) {
 			desc = irq_to_desc(irq);
+			if (!desc)
+				continue;
+
 			data = irq_desc_get_irq_data(desc);
 			cpumask_copy(&affinity_new, data->affinity);
 			cpu_clear(this_cpu, affinity_new);

kernel/rcu/tree_plugin.h

@@ -326,6 +326,7 @@ void rcu_read_unlock_special(struct task_struct *t)
 	special = t->rcu_read_unlock_special;
 	if (special.b.need_qs) {
 		rcu_preempt_qs();
+		t->rcu_read_unlock_special.b.need_qs = false;
 		if (!t->rcu_read_unlock_special.s) {
 			local_irq_restore(flags);
 			return;