[PATCH net-next v3] tipc: fix undefined __ipv6_sock_mc_join compile error

[Ying Xue <ying.xue@windriver.com>]

When CONFIG_IPV6 option is disabled, below error will appear while
building TIPC module:

ERROR: "__ipv6_sock_mc_join" [net/tipc/tipc.ko] undefined!
make[1]: *** [__modpost] Error 1
make: *** [net/tipc/tipc.ko] Error 1

This is because we don't check whether or not the CONFIG_IPV6 is
enabled when calling __ipv6_sock_mc_join().

In addition, especially when TIPC=y, TIPC_MEDIA_UDP=y, and IPV6=m, TIPC
module is also unable to be successfully built. Therefore, we add a
dependency condition like (IPV6=y || IPV6=n) to avoid the error.

Fixes: d0f91938bede ("tipc: add ip/udp media type")
Reported-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Kbuild test robot <kbuild-all@01.org>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: Ying Xue <ying.xue@windriver.com>
---
v3:
  - Move the new dependency from TIPC to TIPC_MEDIA_UDP, which is
    suggested by Willem and David
  - Change IPV6 of new dependency to IPV6=y
  - Change initial err value from 0 to -EAFNOSUPPORT suggested by
    Willem
v2:
  - Fix another compile error when TIPC=y, TIPC_MEDIA_UDP=y, and IPV6=m

 net/tipc/Kconfig     |    1 +
 net/tipc/udp_media.c |    4 +++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/tipc/Kconfig b/net/tipc/Kconfig
index c25a3a1..5bb8fc9 100644
--- a/net/tipc/Kconfig
+++ b/net/tipc/Kconfig
@@ -29,6 +29,7 @@ config TIPC_MEDIA_IB
 config TIPC_MEDIA_UDP
 	bool "IP/UDP media type support"
 	depends on TIPC
+	depends on (IPV6=y || IPV6=n)
 	select NET_UDP_TUNNEL
 	help
 	  Saying Y here will enable support for running TIPC over IP/UDP
diff --git a/net/tipc/udp_media.c b/net/tipc/udp_media.c
index fc2fb11..ee0329d 100644
--- a/net/tipc/udp_media.c
+++ b/net/tipc/udp_media.c
@@ -148,7 +148,7 @@ static int tipc_udp_send_msg(struct net *net, struct sk_buff *skb,
 			     struct tipc_bearer *b,
 			     struct tipc_media_addr *dest)
 {
-	int ttl, err = 0;
+	int ttl, err = -EAFNOSUPPORT;
 	struct udp_bearer *ub;
 	struct udp_media_addr *dst = (struct udp_media_addr *)&dest->value;
 	struct udp_media_addr *src = (struct udp_media_addr *)&b->addr.value;
@@ -247,10 +247,12 @@ static int enable_mcast(struct udp_bearer *ub, struct udp_media_addr *remote)
 		mreqn.imr_multiaddr = remote->ipv4;
 		mreqn.imr_ifindex = ub->ifindex;
 		err = __ip_mc_join_group(sk, &mreqn);
+#if IS_ENABLED(CONFIG_IPV6)
 	} else {
 		if (!ipv6_addr_is_multicast(&remote->ipv6))
 			return 0;
 		err = __ipv6_sock_mc_join(sk, ub->ifindex, &remote->ipv6);
+#endif
 	}
 	return err;
 }
-- 
1.7.9.5


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