[PATCH net 3/4] amt: make pre-query report drops visible
flat view
WARM1d
From: Omar Ramadan <hidden>
Date: 2026-10-08 00:36:16
Also in:
lkml
Subsystem:
amt (automatic multicast tunneling), networking drivers, the rest · Maintainers:
Taehee Yoo, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Revision v1 of 2 in this series.
Revisions (2)
- v1 current
- v2 [diff vs current]
A gateway cannot forward an IGMP or MLD report until it has received the relay's Membership Query for that family. The query supplies the nonce and interval echoed by the Membership Update, so dropping an early report is required, but doing so silently leaves operators with a dark multicast path and no indication why the join never happened. Emit a family-specific debug message before taking the existing drop path. That path already increments tx_dropped, so each discarded report is accounted exactly once. Signed-off-by: Omar Ramadan <redacted> --- drivers/net/amt.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/net/amt.c b/drivers/net/amt.c
index 17dceeaa1..79f2f59bf 100644
--- a/drivers/net/amt.c
+++ b/drivers/net/amt.c@@ -1251,9 +1251,17 @@ static netdev_tx_t amt_dev_xmit(struct sk_buff *skb, struct net_device *dev) /* Gateway only passes IGMP/MLD packets */ if (!report) goto free; + /* A validated report can only be forwarded after the relay's + * family-specific Membership Query supplies the state echoed + * by the Membership Update. Log this readiness failure before + * the shared drop path accounts it. + */ if ((!v6 && !READ_ONCE(amt->ready4)) || - (v6 && !READ_ONCE(amt->ready6))) + (v6 && !READ_ONCE(amt->ready6))) { + netdev_dbg(dev, "drop %s report: no Membership Query for this family yet\n", + v6 ? "MLD" : "IGMP"); goto free; + } if (amt_send_membership_update(amt, skb, v6)) goto free; goto unlock;
--
2.43.0