br_fill_ifinfo() leaves IFLA_BRIDGE_CFM out when the bridge has no MEPs. For a dump that is fine, but a notification sent after the last MEP is deleted then looks like any other RTM_NEWLINK for the bridge, and a listener can't tell that the CFM config is now empty.
Put an empty IFLA_BRIDGE_CFM nest in the message instead when CFM is asked for and the bridge has no MEPs. Ports still get none, as before. Signed-off-by: Abdul Wasey <[email protected]> --- net/bridge/br_netlink.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c index 5160e801d..68ec4529f 100644 --- a/net/bridge/br_netlink.c +++ b/net/bridge/br_netlink.c @@ -603,7 +603,10 @@ static int br_fill_ifinfo(struct sk_buff *skb, struct nlattr *cfm_nest = NULL; int err; - if (!br_cfm_created(br) || port) + /* A bridge with no MEPs gets an empty IFLA_BRIDGE_CFM, so a + * listener can tell that the last MEP is gone. + */ + if (!IS_ENABLED(CONFIG_BRIDGE_CFM) || port) goto done; cfm_nest = nla_nest_start(skb, IFLA_BRIDGE_CFM); -- 2.53.0
