IB/nes: Fix a race condition in nes_inetaddr_event()

This patch has been compile-tested only.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Faisal Latif <faisal.latif@intel.com>
Acked-by: Faisal Latif <fasial.latif@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/nes/nes.c

@@ -178,11 +178,16 @@ static int nes_inetaddr_event(struct notifier_block *notifier,
 					/* fall through */
 				case NETDEV_CHANGEADDR:
 					/* Add the address to the IP table */
-					if (upper_dev)
-						nesvnic->local_ipaddr =
-							((struct in_device *)upper_dev->ip_ptr)->ifa_list->ifa_address;
-					else
+					if (upper_dev) {
+						struct in_device *in;
+
+						rcu_read_lock();
+						in = __in_dev_get_rcu(upper_dev);
+						nesvnic->local_ipaddr = in->ifa_list->ifa_address;
+						rcu_read_unlock();
+					} else {
 						nesvnic->local_ipaddr = ifa->ifa_address;
+					}
 
 					nes_write_indexed(nesdev,
 							NES_IDX_DST_IP_ADDR+(0x10*PCI_FUNC(nesdev->pcidev->devfn)),