[PATCH net-next] net: bridge: cfm: notify userspace on CFM config changes

[Abdul Wasey <w453y.me@gmail.com>]

CFM status changes are sent to userspace by br_cfm_notify(), but config
changes are not. br_afspec() calls br_cfm_parse() without the "changed"
pointer, so creating a MEP, adding a peer or starting CCM transmission
never sends an RTM_NEWLINK. Today the only way to see these changes is
to poll RTM_GETLINK with RTEXT_FILTER_CFM_CONFIG.

Send one RTM_NEWLINK with RTEXT_FILTER_CFM_CONFIG from br_cfm_parse()
once any group in the request has been applied. If a later group in the
same request fails, still send it, since the earlier groups already
changed the config.

br_ifinfo_notify() is not used because it asks for
RTEXT_FILTER_BRVLAN_COMPRESSED, so the message would not carry the CFM
attributes. This calls br_info_notify() the same way br_cfm_notify()
does for status.

Signed-off-by: Abdul Wasey <w453y.me@gmail.com>
---
 net/bridge/br_cfm_netlink.c | 32 +++++++++++++++++++++++---------
 1 file changed, 23 insertions(+), 9 deletions(-)

diff --git a/net/bridge/br_cfm_netlink.c b/net/bridge/br_cfm_netlink.c
index 91b9922dc..56309e6f4 100644
--- a/net/bridge/br_cfm_netlink.c
+++ b/net/bridge/br_cfm_netlink.c
@@ -382,6 +382,7 @@ int br_cfm_parse(struct net_bridge *br, struct net_bridge_port *p,
 		 struct nlattr *attr, int cmd, struct netlink_ext_ack *extack)
 {
 	struct nlattr *tb[IFLA_BRIDGE_CFM_MAX + 1];
+	bool changed = false;
 	int err;
 
 	/* When this function is called for a port then the br pointer is
@@ -399,59 +400,72 @@ int br_cfm_parse(struct net_bridge *br, struct net_bridge_port *p,
 		err = br_mep_create_parse(br, tb[IFLA_BRIDGE_CFM_MEP_CREATE],
 					  extack);
 		if (err)
-			return err;
+			goto out;
+		changed = true;
 	}
 
 	if (tb[IFLA_BRIDGE_CFM_MEP_DELETE]) {
 		err = br_mep_delete_parse(br, tb[IFLA_BRIDGE_CFM_MEP_DELETE],
 					  extack);
 		if (err)
-			return err;
+			goto out;
+		changed = true;
 	}
 
 	if (tb[IFLA_BRIDGE_CFM_MEP_CONFIG]) {
 		err = br_mep_config_parse(br, tb[IFLA_BRIDGE_CFM_MEP_CONFIG],
 					  extack);
 		if (err)
-			return err;
+			goto out;
+		changed = true;
 	}
 
 	if (tb[IFLA_BRIDGE_CFM_CC_CONFIG]) {
 		err = br_cc_config_parse(br, tb[IFLA_BRIDGE_CFM_CC_CONFIG],
 					 extack);
 		if (err)
-			return err;
+			goto out;
+		changed = true;
 	}
 
 	if (tb[IFLA_BRIDGE_CFM_CC_PEER_MEP_ADD]) {
 		err = br_cc_peer_mep_add_parse(br, tb[IFLA_BRIDGE_CFM_CC_PEER_MEP_ADD],
 					       extack);
 		if (err)
-			return err;
+			goto out;
+		changed = true;
 	}
 
 	if (tb[IFLA_BRIDGE_CFM_CC_PEER_MEP_REMOVE]) {
 		err = br_cc_peer_mep_remove_parse(br, tb[IFLA_BRIDGE_CFM_CC_PEER_MEP_REMOVE],
 						  extack);
 		if (err)
-			return err;
+			goto out;
+		changed = true;
 	}
 
 	if (tb[IFLA_BRIDGE_CFM_CC_RDI]) {
 		err = br_cc_rdi_parse(br, tb[IFLA_BRIDGE_CFM_CC_RDI],
 				      extack);
 		if (err)
-			return err;
+			goto out;
+		changed = true;
 	}
 
 	if (tb[IFLA_BRIDGE_CFM_CC_CCM_TX]) {
 		err = br_cc_ccm_tx_parse(br, tb[IFLA_BRIDGE_CFM_CC_CCM_TX],
 					 extack);
 		if (err)
-			return err;
+			goto out;
+		changed = true;
 	}
 
-	return 0;
+out:
+	/* Earlier groups may have been applied even if a later one failed */
+	if (changed)
+		br_info_notify(RTM_NEWLINK, br, NULL, RTEXT_FILTER_CFM_CONFIG);
+
+	return err;
 }
 
 int br_cfm_config_fill_info(struct sk_buff *skb, struct net_bridge *br)
-- 
2.53.0