net: bareudp: avoid uninitialized variable warning

clang points out that building without IPv6 would lead to returning
an uninitialized variable if a packet with family!=AF_INET is
passed into bareudp_udp_encap_recv():

drivers/net/bareudp.c:139:6: error: variable 'err' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
        if (family == AF_INET)
            ^~~~~~~~~~~~~~~~~
drivers/net/bareudp.c:146:15: note: uninitialized use occurs here
        if (unlikely(err)) {
                     ^~~
include/linux/compiler.h:78:42: note: expanded from macro 'unlikely'
 # define unlikely(x)    __builtin_expect(!!(x), 0)
                                            ^
drivers/net/bareudp.c:139:2: note: remove the 'if' if its condition is always true
        if (family == AF_INET)
        ^~~~~~~~~~~~~~~~~~~~~~

This cannot happen in practice, so change the condition in a way that
gcc sees the IPv4 case as unconditionally true here.
For consistency, change all the similar constructs in this file the
same way, using "if(IS_ENABLED())" instead of #if IS_ENABLED()".

Fixes: 571912c69f0e ("net: UDP tunnel encapsulation module for tunnelling different protocols like MPLS, IP, NSH etc.")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/bareudp.c b/drivers/net/bareudp.c
index cc0703c..efd1a1d 100644 (file)
--- a/drivers/net/bareudp.c
+++ b/drivers/net/bareudp.c
@@ -136,25 +136,21 @@ static int bareudp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
        oiph = skb_network_header(skb);
        skb_reset_network_header(skb);
 
-       if (family == AF_INET)
+       if (!IS_ENABLED(CONFIG_IPV6) || family == AF_INET)
                err = IP_ECN_decapsulate(oiph, skb);
-#if IS_ENABLED(CONFIG_IPV6)
        else
                err = IP6_ECN_decapsulate(oiph, skb);
-#endif
 
        if (unlikely(err)) {
                if (log_ecn_error) {
-                       if  (family == AF_INET)
+                       if  (!IS_ENABLED(CONFIG_IPV6) || family == AF_INET)
                                net_info_ratelimited("non-ECT from %pI4 "
                                                     "with TOS=%#x\n",
                                                     &((struct iphdr *)oiph)->saddr,
                                                     ((struct iphdr *)oiph)->tos);
-#if IS_ENABLED(CONFIG_IPV6)
                        else
                                net_info_ratelimited("non-ECT from %pI6\n",
                                                     &((struct ipv6hdr *)oiph)->saddr);
-#endif
                }
                if (err > 1) {
                        ++bareudp->dev->stats.rx_frame_errors;
@@ -350,7 +346,6 @@ free_dst:
        return err;
 }
 
-#if IS_ENABLED(CONFIG_IPV6)
 static int bareudp6_xmit_skb(struct sk_buff *skb, struct net_device *dev,
                             struct bareudp_dev *bareudp,
                             const struct ip_tunnel_info *info)
@@ -411,7 +406,6 @@ free_dst:
        dst_release(dst);
        return err;
 }
-#endif
 
 static netdev_tx_t bareudp_xmit(struct sk_buff *skb, struct net_device *dev)
 {
@@ -435,11 +429,9 @@ static netdev_tx_t bareudp_xmit(struct sk_buff *skb, struct net_device *dev)
        }
 
        rcu_read_lock();
-#if IS_ENABLED(CONFIG_IPV6)
-       if (info->mode & IP_TUNNEL_INFO_IPV6)
+       if (IS_ENABLED(CONFIG_IPV6) && info->mode & IP_TUNNEL_INFO_IPV6)
                err = bareudp6_xmit_skb(skb, dev, bareudp, info);
        else
-#endif
                err = bareudp_xmit_skb(skb, dev, bareudp, info);
 
        rcu_read_unlock();
@@ -467,7 +459,7 @@ static int bareudp_fill_metadata_dst(struct net_device *dev,
 
        use_cache = ip_tunnel_dst_cache_usable(skb, info);
 
-       if (ip_tunnel_info_af(info) == AF_INET) {
+       if (!IS_ENABLED(CONFIG_IPV6) || ip_tunnel_info_af(info) == AF_INET) {
                struct rtable *rt;
                __be32 saddr;
 
@@ -478,7 +470,6 @@ static int bareudp_fill_metadata_dst(struct net_device *dev,
 
                ip_rt_put(rt);
                info->key.u.ipv4.src = saddr;
-#if IS_ENABLED(CONFIG_IPV6)
        } else if (ip_tunnel_info_af(info) == AF_INET6) {
                struct dst_entry *dst;
                struct in6_addr saddr;
@@ -492,7 +483,6 @@ static int bareudp_fill_metadata_dst(struct net_device *dev,
 
                dst_release(dst);
                info->key.u.ipv6.src = saddr;
-#endif
        } else {
                return -EINVAL;
        }

diff --git a/include/net/udp_tunnel.h b/include/net/udp_tunnel.h
index 4b1f95e..e7312ce 100644 (file)
--- a/include/net/udp_tunnel.h
+++ b/include/net/udp_tunnel.h
@@ -143,14 +143,12 @@ void udp_tunnel_xmit_skb(struct rtable *rt, struct sock *sk, struct sk_buff *skb
                         __be16 df, __be16 src_port, __be16 dst_port,
                         bool xnet, bool nocheck);
 
-#if IS_ENABLED(CONFIG_IPV6)
 int udp_tunnel6_xmit_skb(struct dst_entry *dst, struct sock *sk,
                         struct sk_buff *skb,
                         struct net_device *dev, struct in6_addr *saddr,
                         struct in6_addr *daddr,
                         __u8 prio, __u8 ttl, __be32 label,
                         __be16 src_port, __be16 dst_port, bool nocheck);
-#endif
 
 void udp_tunnel_sock_release(struct socket *sock);