bridge br_multicast: Don't refer to BR_INPUT_SKB_CB(skb)->mrouters_only without IGMP snooping.

Without CONFIG_BRIDGE_IGMP_SNOOPING,
BR_INPUT_SKB_CB(skb)->mrouters_only is not appropriately
initialized, so we can see garbage.

A clear option to fix this is to set it even without that
config, but we cannot optimize out the branch.

Let's introduce a macro that returns value of mrouters_only
and let it return 0 without CONFIG_BRIDGE_IGMP_SNOOPING.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 10 insertions, 2 deletions

diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index eb7062d2e9e5..90a9024e5c1e 100644
--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -40,7 +40,7 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
                         goto out;
 
                 mdst = br_mdb_get(br, skb);
-                if (mdst || BR_INPUT_SKB_CB(skb)->mrouters_only)
+                if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb))
                         br_multicast_deliver(mdst, skb);
                 else
                         br_flood_deliver(br, skb);
diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 08a72e63fb8e..d74d570fc848 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -70,7 +70,7 @@ int br_handle_frame_finish(struct sk_buff *skb)
 
         if (is_multicast_ether_addr(dest)) {
                 mdst = br_mdb_get(br, skb);
-                if (mdst || BR_INPUT_SKB_CB(skb)->mrouters_only) {
+                if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) {
                         if ((mdst && !hlist_unhashed(&mdst->mglist)) ||
                             br_multicast_is_router(br))
                                 skb2 = skb;
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index bfb8feb310a6..846d7d1e2075 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -206,12 +206,20 @@ struct net_bridge
 
 struct br_input_skb_cb {
         struct net_device *brdev;
+#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
         int igmp;
         int mrouters_only;
+#endif
 };
 
 #define BR_INPUT_SKB_CB(__skb)  ((struct br_input_skb_cb *)(__skb)->cb)
 
+#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
+# define BR_INPUT_SKB_CB_MROUTERS_ONLY(__skb)   (BR_INPUT_SKB_CB(__skb)->mrouters_only)
+#else
+# define BR_INPUT_SKB_CB_MROUTERS_ONLY(__skb)   (0)
+#endif
+
 extern struct notifier_block br_device_notifier;
 extern const u8 br_group_address[ETH_ALEN];