KVM: s390: Fix assumption that kvm_set_irq_routing is always run successfully

This fixes the assumption that kvm_set_irq_routing is always run
successfully by instead making it equal to the variable r which
we use for returning in the function kvm_arch_vm_ioctl instead
of making r equal to zero when calling this particular function
and incorrectly making the caller of kvm_arch_vm_ioctl think
the function has run successfully.

Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
Message-Id: <1438880754-27149-1-git-send-email-xerofoify@gmail.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

arch/s390/kvm/kvm-s390.c

@@ -962,8 +962,7 @@ long kvm_arch_vm_ioctl(struct file *filp,
 		if (kvm->arch.use_irqchip) {
 			/* Set up dummy routing. */
 			memset(&routing, 0, sizeof(routing));
-			kvm_set_irq_routing(kvm, &routing, 0, 0);
-			r = 0;
+			r = kvm_set_irq_routing(kvm, &routing, 0, 0);
 		}
 		break;
 	}