mac80211: do not overwrite the sequence number if requested

Check if the Tx control flag is set to prevent sequence number overwrites,
and if so, do not assign a new sequence number to the transmitted frame.
Signed-off-by: Mathy Vanhoef <Mathy.Vanhoef@kuleuven.be>
Link: https://lore.kernel.org/r/20200723100153.31631-3-Mathy.Vanhoef@kuleuven.beSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/tx.c

@@ -825,6 +825,9 @@ ieee80211_tx_h_sequence(struct ieee80211_tx_data *tx)
 	if (ieee80211_is_qos_nullfunc(hdr->frame_control))
 		return TX_CONTINUE;
 
+	if (info->control.flags & IEEE80211_TX_CTRL_NO_SEQNO)
+		return TX_CONTINUE;
+
 	/*
 	 * Anything but QoS data that has a sequence number field
 	 * (is long enough) gets a sequence number from the global