s390/qeth: make cast type selection for af_iucv skbs robust

As part of the TX queue selection for af_iucv skbs,
qeth_l3_get_cast_type_rcu() ends up calling qeth_get_ether_cast_type().
Which is rather fragile, since such skbs don't have a proper ETH header
and we rely on it being zeroed out in the right places. Add a separate
case for ETH_P_AF_IUCV instead that does the right thing.

When later building the HW header for such skbs, don't hard-code the
cast type but follow the same path as for other protocol types. Here
the cast type should naturally come from the skb's queue mapping.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
index 4921afb..dd441ea 100644 (file)
--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -1604,8 +1604,10 @@ static int qeth_l3_get_cast_type_rcu(struct sk_buff *skb, struct dst_entry *dst,
        case htons(ETH_P_IPV6):
                return ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) ?
                                RTN_MULTICAST : RTN_UNICAST;
+       case htons(ETH_P_AF_IUCV):
+               return RTN_UNICAST;
        default:
-               /* ... and MAC address */
+               /* OSA only: ... and MAC address */
                return qeth_get_ether_cast_type(skb);
        }
 }
@@ -1651,14 +1653,6 @@ static void qeth_l3_fill_header(struct qeth_qdio_out_q *queue,
        } else {
                hdr->hdr.l3.id = QETH_HEADER_TYPE_LAYER3;
 
-               if (proto == htons(ETH_P_AF_IUCV)) {
-                       l3_hdr->flags = QETH_HDR_IPV6 | QETH_CAST_UNICAST;
-                       l3_hdr->next_hop.addr.s6_addr16[0] = htons(0xfe80);
-                       memcpy(&l3_hdr->next_hop.addr.s6_addr32[2],
-                              iucv_trans_hdr(skb)->destUserID, 8);
-                       return;
-               }
-
                if (skb->ip_summed == CHECKSUM_PARTIAL) {
                        qeth_tx_csum(skb, &hdr->hdr.l3.ext_flags, proto);
                        /* some HW requires combined L3+L4 csum offload: */
@@ -1687,16 +1681,25 @@ static void qeth_l3_fill_header(struct qeth_qdio_out_q *queue,
                cast_type = qeth_l3_get_cast_type_rcu(skb, dst, proto);
        l3_hdr->flags |= qeth_l3_cast_type_to_flag(cast_type);
 
-       if (proto == htons(ETH_P_IP)) {
+       switch (proto) {
+       case htons(ETH_P_IP):
                l3_hdr->next_hop.addr.s6_addr32[3] =
                                        qeth_next_hop_v4_rcu(skb, dst);
-       } else if (proto == htons(ETH_P_IPV6)) {
+               break;
+       case htons(ETH_P_IPV6):
                l3_hdr->next_hop.addr = *qeth_next_hop_v6_rcu(skb, dst);
 
                hdr->hdr.l3.flags |= QETH_HDR_IPV6;
                if (!IS_IQD(card))
                        hdr->hdr.l3.flags |= QETH_HDR_PASSTHRU;
-       } else {
+               break;
+       case htons(ETH_P_AF_IUCV):
+               l3_hdr->next_hop.addr.s6_addr16[0] = htons(0xfe80);
+               memcpy(&l3_hdr->next_hop.addr.s6_addr32[2],
+                      iucv_trans_hdr(skb)->destUserID, 8);
+               l3_hdr->flags |= QETH_HDR_IPV6;
+               break;
+       default:
                /* OSA only: */
                l3_hdr->flags |= QETH_HDR_PASSTHRU;
        }