kernel: add @IPV6 dependency to ipv6 modules

IPv6 modules should all depend on @IPV6, to avoid circular dependencies
problems, especially if they select a module that depends on IPV6 as
well.  In theory, if a package A depends on IPV6, any package doing
'select A' (DEPENDS+= A) should also depend on IPV6; otherwise selecting
A will fail.  Sometimes the build system is forgiving this, but
eventually, and unexpectedly, it may blow up on some other commit.

Alternatively one can conditionally add IPv6 dependencies only if
CONFIG_IPV6 is selected: (DEPENDS+= +IPV6:package6).

Signed-off-by: Eneas U de Queiroz <cotequeiroz@gmail.com>

package/kernel/linux/modules/netfilter.mk

@@ -137,7 +137,7 @@ define KernelPackage/nf-nat6
   SUBMENU:=$(NF_MENU)
   TITLE:=Netfilter IPV6-NAT
   KCONFIG:=$(KCONFIG_NF_NAT6)
-  DEPENDS:=+kmod-nf-conntrack6 +kmod-nf-nat
+  DEPENDS:=@IPV6 +kmod-nf-conntrack6 +kmod-nf-nat
   FILES:=$(foreach mod,$(NF_NAT6-m),$(LINUX_DIR)/net/$(mod).ko)
   AUTOLOAD:=$(call AutoProbe,$(notdir $(NF_NAT6-m)))
 endef
@@ -471,6 +471,7 @@ $(eval $(call KernelPackage,ipt-raw))
 
 define KernelPackage/ipt-raw6
   TITLE:=Netfilter IPv6 raw table support
+  DEPENDS:=@IPV6
   KCONFIG:=CONFIG_IP6_NF_RAW
   FILES:=$(LINUX_DIR)/net/ipv6/netfilter/ip6table_raw.ko
   AUTOLOAD:=$(call AutoProbe,ip6table_raw)
@@ -482,6 +483,7 @@ $(eval $(call KernelPackage,ipt-raw6))
 
 define KernelPackage/ipt-nat6
   TITLE:=IPv6 NAT targets
+  DEPENDS:=@IPV6
   KCONFIG:=$(KCONFIG_IPT_NAT6)
   FILES:=$(foreach mod,$(IPT_NAT6-m),$(LINUX_DIR)/net/$(mod).ko)
   AUTOLOAD:=$(call AutoLoad,43,$(notdir $(IPT_NAT6-m)))
@@ -806,7 +808,7 @@ $(eval $(call KernelPackage,ipt-physdev))
 define KernelPackage/ip6tables
   SUBMENU:=$(NF_MENU)
   TITLE:=IPv6 modules
-  DEPENDS:=+kmod-nf-reject6 +kmod-nf-ipt6 +kmod-ipt-core
+  DEPENDS:=@IPV6 +kmod-nf-reject6 +kmod-nf-ipt6 +kmod-ipt-core
   KCONFIG:=$(KCONFIG_IPT_IPV6)
   FILES:=$(foreach mod,$(IPT_IPV6-m),$(LINUX_DIR)/net/$(mod).ko)
   AUTOLOAD:=$(call AutoLoad,42,$(notdir $(IPT_IPV6-m)))
@@ -821,7 +823,7 @@ $(eval $(call KernelPackage,ip6tables))
 define KernelPackage/ip6tables-extra
   SUBMENU:=$(NF_MENU)
   TITLE:=Extra IPv6 modules
-  DEPENDS:=+kmod-ip6tables
+  DEPENDS:=@IPV6 +kmod-ip6tables
   KCONFIG:=$(KCONFIG_IPT_IPV6_EXTRA)
   FILES:=$(foreach mod,$(IPT_IPV6_EXTRA-m),$(LINUX_DIR)/net/$(mod).ko)
   AUTOLOAD:=$(call AutoLoad,43,$(notdir $(IPT_IPV6_EXTRA-m)))
@@ -911,6 +913,7 @@ $(eval $(call KernelPackage,ebtables-ipv4))
 
 define KernelPackage/ebtables-ipv6
   TITLE:=ebtables: IPv6 support
+  DEPENDS:=@IPV6
   FILES:=$(foreach mod,$(EBTABLES_IP6-m),$(LINUX_DIR)/net/$(mod).ko)
   KCONFIG:=$(KCONFIG_EBTABLES_IP6)
   AUTOLOAD:=$(call AutoProbe,$(notdir $(EBTABLES_IP6-m)))
@@ -1049,7 +1052,7 @@ $(eval $(call KernelPackage,ipt-rpfilter))
 define KernelPackage/nft-core
   SUBMENU:=$(NF_MENU)
   TITLE:=Netfilter nf_tables support
-  DEPENDS:=+kmod-nfnetlink +kmod-nf-reject +kmod-nf-reject6 +kmod-nf-conntrack6 +LINUX_5_4:kmod-nf-nat
+  DEPENDS:=+kmod-nfnetlink +kmod-nf-reject +IPV6:kmod-nf-reject6 +IPV6:kmod-nf-conntrack6 +LINUX_5_4:kmod-nf-nat
   FILES:=$(foreach mod,$(NFT_CORE-m),$(LINUX_DIR)/net/$(mod).ko)
   AUTOLOAD:=$(call AutoProbe,$(notdir $(NFT_CORE-m)))
   KCONFIG:= \
@@ -1106,7 +1109,7 @@ $(eval $(call KernelPackage,nft-nat))
 define KernelPackage/nft-offload
   SUBMENU:=$(NF_MENU)
   TITLE:=Netfilter nf_tables routing/NAT offload support
-  DEPENDS:=+kmod-nf-flow +kmod-nft-nat
+  DEPENDS:=@IPV6 +kmod-nf-flow +kmod-nft-nat
   KCONFIG:= \
 	CONFIG_NF_FLOW_TABLE_INET \
 	CONFIG_NF_FLOW_TABLE_IPV4 \

package/kernel/linux/modules/netsupport.mk

@@ -318,7 +318,7 @@ IPSEC6-m += $(ifeq ($$(strip $$(call CompareKernelPatchVer,$$(KERNEL_PATCHVER),l
 define KernelPackage/ipsec6
   SUBMENU:=$(NETWORK_SUPPORT_MENU)
   TITLE:=IPsec related modules (IPv6)
-  DEPENDS:=kmod-ipsec +kmod-iptunnel6
+  DEPENDS:=@IPV6 kmod-ipsec +kmod-iptunnel6
   KCONFIG:= \
 	CONFIG_INET6_AH \
 	CONFIG_INET6_ESP \
@@ -383,7 +383,7 @@ $(eval $(call KernelPackage,ip-vti))
 define KernelPackage/ip6-vti
   SUBMENU:=$(NETWORK_SUPPORT_MENU)
   TITLE:=IPv6 VTI (Virtual Tunnel Interface)
-  DEPENDS:=+kmod-iptunnel +kmod-ip6-tunnel +kmod-ipsec6
+  DEPENDS:=@IPV6 +kmod-iptunnel +kmod-ip6-tunnel +kmod-ipsec6
   KCONFIG:=CONFIG_IPV6_VTI
   FILES:=$(LINUX_DIR)/net/ipv6/ip6_vti.ko
   AUTOLOAD:=$(call AutoLoad,33,ip6_vti)
@@ -399,7 +399,7 @@ $(eval $(call KernelPackage,ip6-vti))
 define KernelPackage/xfrm-interface
   SUBMENU:=$(NETWORK_SUPPORT_MENU)
   TITLE:=IPsec XFRM Interface
-  DEPENDS:=+kmod-ipsec4 +kmod-ipsec6 @!LINUX_4_14
+  DEPENDS:=+kmod-ipsec4 +@IPV6:kmod-ipsec6 @!LINUX_4_14
   KCONFIG:=CONFIG_XFRM_INTERFACE
   FILES:=$(LINUX_DIR)/net/xfrm/xfrm_interface.ko
   AUTOLOAD:=$(call AutoProbe,xfrm_interface)