batman-adv: support multicast optimization in bridged setups

Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>

batman-adv/Makefile

@@ -69,8 +69,14 @@ NOSTDINC_FLAGS = \
 	-include backport/backport.h \
 	-include $(PKG_BUILD_DIR)/compat-hacks.h
 
+COMPAT_SOURCES = \
+	$(if $(CONFIG_KMOD_BATMAN_ADV_MCAST),../../compat-sources/net/core/skbuff.o,) \
+	$(if $(CONFIG_KMOD_BATMAN_ADV_MCAST),../../compat-sources/net/ipv4/igmp.o,) \
+	$(if $(CONFIG_KMOD_BATMAN_ADV_MCAST),../../compat-sources/net/ipv6/mcast_snoop.o,) \
+
 define Build/Compile
-	+$(MAKE) $(PKG_JOBS) -C "$(LINUX_DIR)" \
+	+env "batman-adv-y=$(COMPAT_SOURCES)" \
+	$(MAKE) $(PKG_JOBS) -C "$(LINUX_DIR)" \
 		ARCH="$(LINUX_KARCH)" \
 		CROSS_COMPILE="$(TARGET_CROSS)" \
 		SUBDIRS="$(PKG_BUILD_DIR)/net/batman-adv" \

batman-adv/files/compat-hacks.h

@@ -31,6 +31,17 @@
 
 #endif /* < KERNEL_VERSION(4, 5, 0) */
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 2, 0)
+
+struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
+				     unsigned int transport_len,
+				     __sum16(*skb_chkf)(struct sk_buff *skb));
+
+int ip_mc_check_igmp(struct sk_buff *skb, struct sk_buff **skb_trimmed);
+
+int ipv6_mc_check_mld(struct sk_buff *skb, struct sk_buff **skb_trimmed);
+
+#endif /* < KERNEL_VERSION(4, 2, 0) */
 
 #if LINUX_VERSION_CODE < KERNEL_VERSION(4, 3, 0)