bridge: add proper RCU annotation to should_route_hook

Add br_should_route_hook_t typedef, this is the only way we can
get a clean RCU implementation for function pointer.

Move route_hook to location where it is used.

Signed-off-by: Eric Dumazet <[email protected]>
Signed-off-by: Stephen Hemminger <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: Eric Dumazet

include/linux/if_bridge.h

@@ -102,7 +102,9 @@ struct __fdb_entry {
 #include <linux/netdevice.h>
 
 extern void brioctl_set(int (*ioctl_hook)(struct net *, unsigned int, void __user *));
-extern int (*br_should_route_hook)(struct sk_buff *skb);
+
+typedef int (*br_should_route_hook_t)(struct sk_buff *skb);
+extern br_should_route_hook_t __rcu *br_should_route_hook;
 
 #endif
 

net/bridge/br.c

@@ -22,8 +22,6 @@
 
 #include "br_private.h"
 
-int (*br_should_route_hook)(struct sk_buff *skb);
-
 static const struct stp_proto br_stp_proto = {
 	.rcv	= br_stp_rcv,
 };
@@ -102,8 +100,6 @@ static void __exit br_deinit(void)
 	br_fdb_fini();
 }
 
-EXPORT_SYMBOL(br_should_route_hook);
-
 module_init(br_init)
 module_exit(br_deinit)
 MODULE_LICENSE("GPL");

net/bridge/br_input.c

@@ -21,6 +21,10 @@
 /* Bridge group multicast address 802.1d (pg 51). */
 const u8 br_group_address[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 };
 
+/* Hook for brouter */
+br_should_route_hook_t __rcu *br_should_route_hook __read_mostly;
+EXPORT_SYMBOL(br_should_route_hook);
+
 static int br_pass_frame_up(struct sk_buff *skb)
 {
 	struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
@@ -139,7 +143,7 @@ struct sk_buff *br_handle_frame(struct sk_buff *skb)
 {
 	struct net_bridge_port *p;
 	const unsigned char *dest = eth_hdr(skb)->h_dest;
-	int (*rhook)(struct sk_buff *skb);
+	br_should_route_hook_t *rhook;
 
 	if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
 		return skb;
@@ -173,8 +177,8 @@ struct sk_buff *br_handle_frame(struct sk_buff *skb)
 	switch (p->state) {
 	case BR_STATE_FORWARDING:
 		rhook = rcu_dereference(br_should_route_hook);
-		if (rhook != NULL) {
-			if (rhook(skb))
+		if (rhook) {
+			if ((*rhook)(skb))
 				return skb;
 			dest = eth_hdr(skb)->h_dest;
 		}

net/bridge/netfilter/ebtable_broute.c

@@ -87,7 +87,8 @@ static int __init ebtable_broute_init(void)
 	if (ret < 0)
 		return ret;
 	/* see br_input.c */
-	rcu_assign_pointer(br_should_route_hook, ebt_broute);
+	rcu_assign_pointer(br_should_route_hook,
+			   (br_should_route_hook_t *)ebt_broute);
 	return 0;
 }