Patch "s390/qeth: fix thinko in IPv4 multicast address tracking" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

s390/qeth: fix thinko in IPv4 multicast address tracking

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
s390-qeth-fix-thinko-in-ipv4-multicast-address-tracking.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Julian Wiedmann <[email protected]>
Date: Fri, 1 Dec 2017 10:14:49 +0100
Subject: s390/qeth: fix thinko in IPv4 multicast address tracking

From: Julian Wiedmann <[email protected]>

[ Upsteam commit bc3ab70584696cb798b9e1e0ac8e6ced5fd4c3b8 ]

Commit 5f78e29ceebf ("qeth: optimize IP handling in rx_mode callback") reworked how secondary addresses are managed for qeth devices. Instead of dropping & subsequently re-adding all addresses on every ndo_set_rx_mode() call, qeth now keeps track of the addresses that are currently registered with the HW.
On a ndo_set_rx_mode(), we thus only need to do (de-)registration requests for the addresses that have actually changed.

On L3 devices, the lookup for IPv4 Multicast addresses checks the wrong hashtable - and thus never finds a match. As a result, we first delete *all* such addresses, and then re-add them again. So each set_rx_mode() causes a short period where the IPv4 Multicast addresses are not registered, and the card stops forwarding inbound traffic for them.

Fix this by setting the ->is_multicast flag on the lookup object, thus enabling qeth_l3_ip_from_hash() to search the correct hashtable and find a match there.

---
 drivers/s390/net/qeth_l3_main.c |    1 +
 1 file changed, 1 insertion(+)

@@ -1376,6 +1376,7 @@ qeth_l3_add_mc_to_hash(struct qeth_card
 
 		tmp->u.a4.addr = be32_to_cpu(im4->multiaddr);
 		memcpy(tmp->mac, buf, sizeof(tmp->mac));
+		tmp->is_multicast = 1;
 
 		ipm = qeth_l3_ip_from_hash(card, tmp);
 		if (ipm) {

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/s390-qeth-fix-thinko-in-ipv4-multicast-address-tracking.patch queue-4.14/s390-qeth-fix-gso-throughput-regression.patch queue-4.14/s390-qeth-fix-early-exit-from-error-path.patch queue-4.14/s390-qeth-build-max-size-gso-skbs-on-l2-devices.patch