qeth: l3 fix rcu splat in xmit

when use dst_get_neighbour to get neighbour, we need
rcu_read_lock to protect, since dst_get_neighbour uses
rcu_dereference.

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
index e4c1176..4d5307d 100644 (file)
--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -2756,11 +2756,13 @@ int inline qeth_l3_get_cast_type(struct qeth_card *card, struct sk_buff *skb)
        struct neighbour *n = NULL;
        struct dst_entry *dst;
 
+       rcu_read_lock();
        dst = skb_dst(skb);
        if (dst)
                n = dst_get_neighbour(dst);
        if (n) {
                cast_type = n->type;
+               rcu_read_unlock();
                if ((cast_type == RTN_BROADCAST) ||
                    (cast_type == RTN_MULTICAST) ||
                    (cast_type == RTN_ANYCAST))
@@ -2768,6 +2770,8 @@ int inline qeth_l3_get_cast_type(struct qeth_card *card, struct sk_buff *skb)
                else
                        return RTN_UNSPEC;
        }
+       rcu_read_unlock();
+
        /* try something else */
        if (skb->protocol == ETH_P_IPV6)
                return (skb_network_header(skb)[24] == 0xff) ?
@@ -2847,6 +2851,8 @@ static void qeth_l3_fill_header(struct qeth_card *card, struct qeth_hdr *hdr,
        }
 
        hdr->hdr.l3.length = skb->len - sizeof(struct qeth_hdr);
+
+       rcu_read_lock();
        dst = skb_dst(skb);
        if (dst)
                n = dst_get_neighbour(dst);
@@ -2893,6 +2899,7 @@ static void qeth_l3_fill_header(struct qeth_card *card, struct qeth_hdr *hdr,
                                QETH_CAST_UNICAST | QETH_HDR_PASSTHRU;
                }
        }
+       rcu_read_unlock();
 }
 
 static inline void qeth_l3_hdr_csum(struct qeth_card *card,