qeth: fix race condition during device startup

QDIO is running independent from netdevice state. We are not
allowed to schedule NAPI in case the netdevice is not open.

Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index 09ab6a2..e6b2df0 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -2903,7 +2903,7 @@
 {
 	struct qeth_card *card = (struct qeth_card *)card_ptr;
 
-	if (card->dev)
+	if (card->dev && (card->dev->flags & IFF_UP))
 		napi_schedule(&card->napi);
 }
 EXPORT_SYMBOL_GPL(qeth_qdio_start_poll);