[PATCH net] net: dsa: motorcomm: Reread port flags on bridge joining

[PATCH net] net: dsa: motorcomm: Reread port flags on bridge joining

[David Yang]

DSA replays neither BR_ISOLATED nor BR_HAIRPIN_MODE on join (e.g. a LAG
member rejoining its bond), so the cached flags survive into the next
bridge join and program stale hairpin and port isolation state. Sync
them from the bridge port.

Fixes: 186623f4aa72 ("net: dsa: yt921x: Add support for Motorcomm YT921x")
Signed-off-by: David Yang <mmyangfl@gmail.com>
---
 drivers/net/dsa/motorcomm/chip.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/net/dsa/motorcomm/chip.c b/drivers/net/dsa/motorcomm/chip.c
index 33e5fc127244..fcc3a299ed66 100644
--- a/drivers/net/dsa/motorcomm/chip.c
+++ b/drivers/net/dsa/motorcomm/chip.c
@@ -1405,6 +1405,9 @@ yt921x_dsa_port_bridge_join(struct dsa_switch *ds, int port,
 			    struct netlink_ext_ack *extack)
 {
 	struct yt921x_priv *priv = dsa_to_yt921x_priv(ds);
+	struct yt921x_port *pp = &priv->ports[port];
+	struct net_device *brport_dev;
+	struct dsa_port *dp;
 	u16 ports_mask;
 	int res;
 
@@ -1414,7 +1417,12 @@ yt921x_dsa_port_bridge_join(struct dsa_switch *ds, int port,
 	ports_mask = dsa_bridge_ports(ds, bridge.dev);
 	ports_mask |= priv->cpu_ports_mask;
 
+	dp = dsa_to_port(ds, port);
+	brport_dev = dsa_port_to_bridge_port(dp);
+
 	mutex_lock(&priv->reg_lock);
+	pp->isolated = br_port_flag_is_set(brport_dev, BR_ISOLATED);
+	pp->hairpin = br_port_flag_is_set(brport_dev, BR_HAIRPIN_MODE);
 	res = yt921x_bridge_join(priv, port, ports_mask);
 	mutex_unlock(&priv->reg_lock);
 
-- 
2.53.0

Re: [PATCH net] net: dsa: motorcomm: Reread port flags on bridge joining

[netdev-bot+sinfo]

Hi!

This is an automated message. This series looks like a fix, but its
commit messages seem to be missing some information:

 - How the issue was discovered, e.g. hit in production, hit during
   development, syzbot report, manual code inspection, LLM or static
   analysis tool scan.

 - Whether the issue was actually triggered, or is only theoretical
   (e.g. found by code inspection). If it was triggered please include
   the symptoms, like the stack trace or error messages.

Please do not repost the series just to address the above. Instead,
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