From: Felix Fietkau <nbd@nbd.name>
Date: Sat, 25 Jul 2020 10:42:30 +0200
Subject: [PATCH] mac80211: remove STA txq pending airtime underflow
 warning

This warning can trigger if there is a mismatch between frames that were
sent with the sta pointer set vs tx status frames reported for the sta address.

This can happen due to race conditions on re-creating stations, or even
in the case of .sta_add/remove being used instead of .sta_state, which can cause
frames to be sent to a station that has not been uploaded yet.

If there is an actual underflow issue, it should show up in the device airtime
warning below, so it is better to remove this one.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---

--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -1924,9 +1924,7 @@ void ieee80211_sta_update_pending_airtim
 	if (sta) {
 		tx_pending = atomic_sub_return(tx_airtime,
 					       &sta->airtime[ac].aql_tx_pending);
-		if (WARN_ONCE(tx_pending < 0,
-			      "STA %pM AC %d txq pending airtime underflow: %u, %u",
-			      sta->addr, ac, tx_pending, tx_airtime))
+		if (tx_pending < 0)
 			atomic_cmpxchg(&sta->airtime[ac].aql_tx_pending,
 				       tx_pending, 0);
 	}