Linux Ethernet Bridging - Jul 2019 - [Bridge] [PATCH] [net-next] netfilter: bridge: make NF_TABLES_BRIDGE tristate

The new nft_meta_bridge code fails to link as built-in when NF_TABLES
is a loadable module.

net/bridge/netfilter/nft_meta_bridge.o: In function
`nft_meta_bridge_get_eval':
nft_meta_bridge.c:(.text+0x1e8): undefined reference to `nft_meta_get_eval'
net/bridge/netfilter/nft_meta_bridge.o: In function
`nft_meta_bridge_get_init':
nft_meta_bridge.c:(.text+0x468): undefined reference to `nft_meta_get_init'
nft_meta_bridge.c:(.text+0x49c): undefined reference to `nft_parse_register'
nft_meta_bridge.c:(.text+0x4cc): undefined reference to
`nft_validate_register_store'
net/bridge/netfilter/nft_meta_bridge.o: In function
`nft_meta_bridge_module_exit':
nft_meta_bridge.c:(.exit.text+0x14): undefined reference to
`nft_unregister_expr'
net/bridge/netfilter/nft_meta_bridge.o: In function
`nft_meta_bridge_module_init':
nft_meta_bridge.c:(.init.text+0x14): undefined reference to
`nft_register_expr'
net/bridge/netfilter/nft_meta_bridge.o:(.rodata+0x60): undefined reference to
`nft_meta_get_dump'
net/bridge/netfilter/nft_meta_bridge.o:(.rodata+0x88): undefined reference to
`nft_meta_set_eval'

This can happen because the NF_TABLES_BRIDGE dependency itself is just a
'bool'.  Make the symbol a 'tristate' instead so Kconfig can
propagate the
dependencies correctly.

Fixes: 30e103fe24de ("netfilter: nft_meta: move bridge meta keys into
nft_meta_bridge")
Signed-off-by: Arnd Bergmann <arnd at arndb.de>
---
 net/bridge/netfilter/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bridge/netfilter/Kconfig b/net/bridge/netfilter/Kconfig
index 154fa558bb90..d0c75d7ec074 100644
--- a/net/bridge/netfilter/Kconfig
+++ b/net/bridge/netfilter/Kconfig
@@ -6,7 +6,7 @@
 menuconfig NF_TABLES_BRIDGE
 	depends on BRIDGE && NETFILTER && NF_TABLES
 	select NETFILTER_FAMILY_BRIDGE
-	bool "Ethernet Bridge nf_tables support"
+	tristate "Ethernet Bridge nf_tables support"
 
 if NF_TABLES_BRIDGE
 
-- 
2.20.0

On Wed, Jul 10, 2019 at 10:08:20AM +0200, Arnd Bergmann
wrote:
> The new nft_meta_bridge code fails to link as built-in when NF_TABLES
> is a loadable module.
Applied, thanks Arnd.

On Wed, Jul 10, 2019 at 10:08:20AM +0200, Arnd Bergmann
wrote:
> The new nft_meta_bridge code fails to link as built-in when NF_TABLES
> is a loadable module.
> 
> net/bridge/netfilter/nft_meta_bridge.o: In function
`nft_meta_bridge_get_eval':
> nft_meta_bridge.c:(.text+0x1e8): undefined reference to
`nft_meta_get_eval'
> net/bridge/netfilter/nft_meta_bridge.o: In function
`nft_meta_bridge_get_init':
> nft_meta_bridge.c:(.text+0x468): undefined reference to
`nft_meta_get_init'
> nft_meta_bridge.c:(.text+0x49c): undefined reference to
`nft_parse_register'
> nft_meta_bridge.c:(.text+0x4cc): undefined reference to
`nft_validate_register_store'
> net/bridge/netfilter/nft_meta_bridge.o: In function
`nft_meta_bridge_module_exit':
> nft_meta_bridge.c:(.exit.text+0x14): undefined reference to
`nft_unregister_expr'
> net/bridge/netfilter/nft_meta_bridge.o: In function
`nft_meta_bridge_module_init':
> nft_meta_bridge.c:(.init.text+0x14): undefined reference to
`nft_register_expr'
> net/bridge/netfilter/nft_meta_bridge.o:(.rodata+0x60): undefined reference
to `nft_meta_get_dump'
> net/bridge/netfilter/nft_meta_bridge.o:(.rodata+0x88): undefined reference
to `nft_meta_set_eval'
> 
> This can happen because the NF_TABLES_BRIDGE dependency itself is just a
> 'bool'.  Make the symbol a 'tristate' instead so Kconfig
can propagate the
> dependencies correctly.
Hm. Something breaks here. Investigating. Looks like bridge support is
gone after this, nft fails to register the filter chain type:

# nft add table bridge x
# nft add chain bridge x y { type filter hook input priority 0\; }
Error: Could not process rule: No such file or directory