[PATCH net v2 1/2] bridge: cfm: Store the new CC configuration before enabling peers

[Baek Kyu, Kim]

br_cfm_cc_config_set() enables existing peers before storing the new
CC configuration. The receive timer therefore starts with the previous
expected interval, delaying CCM loss detection when enabling CC with a
shorter interval. For example, disabling CC at 1s and re-enabling it at
100ms schedules the first check after 250ms instead of 25ms, before
rounding to jiffies.

Save the disabled-to-enabled transition and store the new configuration
before enabling peers. Keep cancellation on disable before replacing
the configuration.

Fixes: dc32cbb3dbd7 ("bridge: cfm: Kernel space implementation of CFM. CCM frame RX added.")
Signed-off-by: Baek Kyu, Kim <pocj8ur4in@xxxxxxxxx>
---
On the combined v2 kernel under ARM64 QEMU/KVM, all 8 CC interval and
transition checks passed with bridge/veth and netlink configuration.

 net/bridge/br_cfm.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/net/bridge/br_cfm.c b/net/bridge/br_cfm.c
index 9dcc97d63a6f..28b40dbf4073 100644
--- a/net/bridge/br_cfm.c
+++ b/net/bridge/br_cfm.c
@@ -634,6 +634,7 @@ int br_cfm_cc_config_set(struct net_bridge *br,
 {
 	struct br_cfm_peer_mep *peer_mep;
 	struct br_cfm_mep *mep;
+	bool enable;
 
 	ASSERT_RTNL();
 
@@ -648,17 +649,20 @@ int br_cfm_cc_config_set(struct net_bridge *br,
 	if (memcmp(config, &mep->cc_config, sizeof(*config)) == 0)
 		return 0;
 
-	if (config->enable && !mep->cc_config.enable)
-		/* CC is enabled */
-		hlist_for_each_entry(peer_mep, &mep->peer_mep_list, head)
-			cc_peer_enable(peer_mep);
-
 	if (!config->enable && mep->cc_config.enable)
 		/* CC is disabled */
 		hlist_for_each_entry(peer_mep, &mep->peer_mep_list, head)
 			cc_peer_disable(peer_mep);
 
+	enable = config->enable && !mep->cc_config.enable;
+
 	mep->cc_config = *config;
+
+	if (enable)
+		/* CC is enabled */
+		hlist_for_each_entry(peer_mep, &mep->peer_mep_list, head)
+			cc_peer_enable(peer_mep);
+
 	mep->ccm_rx_snumber = 0;
 	mep->ccm_tx_snumber = 1;
 
-- 
2.55.0