mac80211: do not use low data rates for data frames with no ack flag

Data Frames with no ack flag set should be handled by the rate
controler. Make sure we reach the rate controler by returning early
from rate_control_send_low if the frame is a data frame with no ack
flag.
Signed-off-by: NPhilipp Borgers <borgers@mi.fu-berlin.de>
Link: https://lore.kernel.org/r/20210519122019.92359-3-borgers@mi.fu-berlin.deSigned-off-by: NJohannes Berg <johannes.berg@intel.com>

net/mac80211/rate.c

@@ -396,6 +396,10 @@ static bool rate_control_send_low(struct ieee80211_sta *pubsta,
 	int mcast_rate;
 	bool use_basicrate = false;
 
+	if (ieee80211_is_tx_data(txrc->skb) &&
+	    info->flags & IEEE80211_TX_CTL_NO_ACK)
+		return false;
+
 	if (!pubsta || rc_no_data_or_no_ack_use_min(txrc)) {
 		__rate_control_send_low(txrc->hw, sband, pubsta, info,
 					txrc->rate_idx_mask);