s390/qeth: lock IP table while applying takeover changes

Modifying the flags of an IP addr object needs to be protected against
eg. concurrent removal of the same object from the IP table.

Fixes: 5f78e29ceebf ("qeth: optimize IP handling in rx_mode callback")
Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/s390/net/qeth_l3_sys.c b/drivers/s390/net/qeth_l3_sys.c
index e256928..aa676b4 100644
--- a/drivers/s390/net/qeth_l3_sys.c
+++ b/drivers/s390/net/qeth_l3_sys.c
@@ -395,6 +395,7 @@
 		goto out;
 	card->ipato.enabled = enable;
 
+	spin_lock_bh(&card->ip_lock);
 	hash_for_each(card->ip_htable, i, addr, hnode) {
 		if (addr->type != QETH_IP_TYPE_NORMAL)
 			continue;
@@ -403,6 +404,7 @@
 		else if (qeth_l3_is_addr_covered_by_ipato(card, addr))
 			addr->set_flags |= QETH_IPA_SETIP_TAKEOVER_FLAG;
 	}
+	spin_unlock_bh(&card->ip_lock);
 out:
 	mutex_unlock(&card->conf_mutex);
 	return rc ? rc : count;