s390/qeth: lock IP table while applying takeover changes

[ Upstream commit 8a03a369 ]

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: 5f78e29c ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/s390/net/qeth_l3_sys.c

@@ -397,6 +397,7 @@ static ssize_t qeth_l3_dev_ipato_enable_store(struct device *dev,
 		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;
@@ -405,6 +406,7 @@ static ssize_t qeth_l3_dev_ipato_enable_store(struct device *dev,
 		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;