[PATCH net 1/1] net: bridge: cfm: use a per-bridge frame type

From: Yilin Zhu <[email protected]>

CFM registers a bridge frame handler when the first MEP is created and
unregisters it when the last MEP is deleted. The registered object also
contains the hlist_node used by the bridge-local frame_type_list.

The CFM frame type is currently global, so enabling CFM on multiple
bridges links the same hlist_node into multiple bridge-local lists. A
later unregister on one bridge can then operate on list state belonging
to another bridge.

Move the CFM frame type into struct net_bridge and register/unregister
the bridge-owned object. This keeps frame handler list membership local
to the bridge while preserving the existing first-MEP/last-MEP lifetime.

Fixes: dc32cbb3dbd7 ("bridge: cfm: Kernel space implementation of CFM. CCM frame RX added.")
Cc: [email protected]
Reported-by: Yuan Tan <[email protected]>
Reported-by: Yifan Wu <[email protected]>
Reported-by: Juefei Pu <[email protected]>
Reported-by: Xin Liu <[email protected]>
Co-developed-by: Peihan Liu <[email protected]>
Signed-off-by: Peihan Liu <[email protected]>
Signed-off-by: Yilin Zhu <[email protected]>
Signed-off-by: Ren Wei <[email protected]>
---
 net/bridge/br_cfm.c     | 14 ++++++--------
 net/bridge/br_private.h | 18 +++++++++++-------
 2 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/net/bridge/br_cfm.c b/net/bridge/br_cfm.c
index 118c7ea48c35..547c7415c0ea 100644
--- a/net/bridge/br_cfm.c
+++ b/net/bridge/br_cfm.c
@@ -489,11 +489,6 @@ static int br_cfm_frame_rx(struct net_bridge_port *port, struct sk_buff *skb)
 	return 1;
 }
 
-static struct br_frame_type cfm_frame_type __read_mostly = {
-	.type = cpu_to_be16(ETH_P_CFM),
-	.frame_handler = br_cfm_frame_rx,
-};
-
 int br_cfm_mep_create(struct net_bridge *br,
 		      const u32 instance,
 		      struct br_cfm_mep_create *const create,
@@ -558,8 +553,11 @@ int br_cfm_mep_create(struct net_bridge *br,
 	INIT_HLIST_HEAD(&mep->peer_mep_list);
 	INIT_DELAYED_WORK(&mep->ccm_tx_dwork, ccm_tx_work_expired);
 
-	if (hlist_empty(&br->mep_list))
-		br_add_frame(br, &cfm_frame_type);
+	if (hlist_empty(&br->mep_list)) {
+		br->cfm_frame_type.type = cpu_to_be16(ETH_P_CFM);
+		br->cfm_frame_type.frame_handler = br_cfm_frame_rx;
+		br_add_frame(br, &br->cfm_frame_type);
+	}
 
 	hlist_add_tail_rcu(&mep->head, &br->mep_list);
 
@@ -588,7 +586,7 @@ static void mep_delete_implementation(struct net_bridge *br,
 	kfree_rcu(mep, rcu);
 
 	if (hlist_empty(&br->mep_list))
-		br_del_frame(br, &cfm_frame_type);
+		br_del_frame(br, &br->cfm_frame_type);
 }
 
 int br_cfm_mep_delete(struct net_bridge *br,
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index bed1b1d9b282..a3ed9ee826f5 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -61,6 +61,9 @@ typedef struct bridge_id bridge_id;
 typedef struct mac_addr mac_addr;
 typedef __u16 port_id;
 
+struct net_bridge_port;
+struct sk_buff;
+
 struct bridge_id {
 	unsigned char	prio[2];
 	unsigned char	addr[ETH_ALEN];
@@ -70,6 +73,13 @@ struct mac_addr {
 	unsigned char	addr[ETH_ALEN];
 };
 
+struct br_frame_type {
+	__be16			type;
+	int			(*frame_handler)(struct net_bridge_port *port,
+						 struct sk_buff *skb);
+	struct hlist_node	list;
+};
+
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 /* our own querier */
 struct bridge_mcast_own_query {
@@ -585,6 +595,7 @@ struct net_bridge {
 	struct hlist_head		mrp_list;
 #endif
 #if IS_ENABLED(CONFIG_BRIDGE_CFM)
+	struct br_frame_type	cfm_frame_type;
 	struct hlist_head		mep_list;
 #endif
 };
@@ -926,13 +937,6 @@ int nbp_backup_change(struct net_bridge_port *p, struct net_device *backup_dev);
 int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb);
 rx_handler_func_t *br_get_rx_handler(const struct net_device *dev);
 
-struct br_frame_type {
-	__be16			type;
-	int			(*frame_handler)(struct net_bridge_port *port,
-						 struct sk_buff *skb);
-	struct hlist_node	list;
-};
-
 void br_add_frame(struct net_bridge *br, struct br_frame_type *ft);
 void br_del_frame(struct net_bridge *br, struct br_frame_type *ft);
 
-- 
2.47.3