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

Pull irq fix from Ingo Molnar:
 "Fix a race in the IRQ resend mechanism, which can result in a NULL
  dereference crash"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  genirq: Prevent NULL pointer dereference in resend_irqs()

Author: torvalds

kernel/irq/resend.c

@@ -36,6 +36,8 @@ static void resend_irqs(unsigned long arg)
 		irq = find_first_bit(irqs_resend, nr_irqs);
 		clear_bit(irq, irqs_resend);
 		desc = irq_to_desc(irq);
+		if (!desc)
+			continue;
 		local_irq_disable();
 		desc->handle_irq(desc);
 		local_irq_enable();