Linux Ethernet Bridging - Jan 2015 - [Bridge] [PATCH] bridge: only provide proxy ARP when CONFIG_INET is enabled

When IPV4 support is disabled, we cannot call arp_send from
the bridge code, which would result in a kernel link error:

net/built-in.o: In function `br_handle_frame_finish':
:(.text+0x59914): undefined reference to `arp_send'
:(.text+0x59a50): undefined reference to `arp_tbl'

This makes the newly added proxy ARP support in the bridge
code depend on the CONFIG_INET symbol and lets the compiler
optimize the code out to avoid the link error.

Signed-off-by: Arnd Bergmann <arnd at arndb.de>
Fixes: 958501163ddd ("bridge: Add support for IEEE 802.11 Proxy ARP")
Cc: Kyeyoon Park <kyeyoonp at codeaurora.org>

diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 1f1de715197c..e2aa7be3a847 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -154,7 +154,8 @@ int br_handle_frame_finish(struct sk_buff *skb)
 	dst = NULL;
 
 	if (is_broadcast_ether_addr(dest)) {
-		if (p->flags & BR_PROXYARP &&
+		if (IS_ENABLED(CONFIG_INET) &&
+		    p->flags & BR_PROXYARP &&
 		    skb->protocol == htons(ETH_P_ARP))
 			br_do_proxy_arp(skb, br, vid);

On Tue, Jan 13, 2015 at 6:10 AM, Arnd Bergmann <arnd at arndb.de>
wrote:
> When IPV4 support is disabled, we cannot call arp_send from
> the bridge code, which would result in a kernel link error:
>
> net/built-in.o: In function `br_handle_frame_finish':
> :(.text+0x59914): undefined reference to `arp_send'
> :(.text+0x59a50): undefined reference to `arp_tbl'
>
> This makes the newly added proxy ARP support in the bridge
> code depend on the CONFIG_INET symbol and lets the compiler
> optimize the code out to avoid the link error.
>
Not sure how much sense to make CONFIG_BRIDGE depend
on CONFIG_INET, at least CONFIG_BONDING does.

From: Arnd Bergmann <arnd at arndb.de>
Date: Tue, 13 Jan 2015 15:10:27 +0100
> When IPV4 support is disabled, we cannot call arp_send from
> the bridge code, which would result in a kernel link error:
> 
> net/built-in.o: In function `br_handle_frame_finish':
> :(.text+0x59914): undefined reference to `arp_send'
> :(.text+0x59a50): undefined reference to `arp_tbl'
> 
> This makes the newly added proxy ARP support in the bridge
> code depend on the CONFIG_INET symbol and lets the compiler
> optimize the code out to avoid the link error.
> 
> Signed-off-by: Arnd Bergmann <arnd at arndb.de>
> Fixes: 958501163ddd ("bridge: Add support for IEEE 802.11 Proxy
ARP")
Applied, thanks Arnd.