staging/lustre/lnet: NI shutdown may loop forever

lnet_shutdown_lndnis() may enter endless loop if there is a busy NI,
this is injected by LNet SMP improvements. It's fixed in this patch.
Signed-off-by: Liang Zhen <liang.zhen@intel.com>
Reviewed-on: http://review.whamcloud.com/9706
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4780Reviewed-by: Isaac Huang <he.huang@intel.com>
Reviewed-by: Bobi Jam <bobijam@gmail.com>
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lnet/lnet/api-ni.c

@@ -986,12 +986,11 @@ lnet_shutdown_lndnis (void)
 			break;
 		}
 
-		while (!list_empty(&ni->ni_list)) {
+		if (!list_empty(&ni->ni_list)) {
 			lnet_net_unlock(LNET_LOCK_EX);
 			++i;
 			if ((i & (-i)) == i) {
-				CDEBUG(D_WARNING,
-				       "Waiting for zombie LNI %s\n",
+				CDEBUG(D_WARNING, "Waiting for zombie LNI %s\n",
 				       libcfs_nid2str(ni->ni_nid));
 			}
 			set_current_state(TASK_UNINTERRUPTIBLE);
@@ -1016,6 +1015,8 @@ lnet_shutdown_lndnis (void)
 			       libcfs_nid2str(ni->ni_nid));
 
 		lnet_ni_free(ni);
+		i = 2;
+
 		lnet_net_lock(LNET_LOCK_EX);
 	}