mac80211: fix time-is-after bug in mlme

The incorrect timeout check caused probing to happen when it did
not need to happen.  This in turn caused tx performance drop
for around 5 seconds in ath10k-ct driver.  Possibly that tx drop
is due to a secondary issue, but fixing the probe to not happen
when traffic is running fixes the symptom.

Signed-off-by: Ben Greear <greearb@candelatech.com>
Fixes: 9abf4e4 ("mac80211: optimize station connection monitor")
Acked-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20210330230749.14097-1-greearb@candelatech.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/mlme.c

@@ -4707,7 +4707,10 @@ static void ieee80211_sta_conn_mon_timer(struct timer_list *t)
 		timeout = sta->rx_stats.last_rx;
 	timeout += IEEE80211_CONNECTION_IDLE_TIME;
 
-	if (time_is_before_jiffies(timeout)) {
+	/* If timeout is after now, then update timer to fire at
+	 * the later date, but do not actually probe at this time.
+	 */
+	if (time_is_after_jiffies(timeout)) {
 		mod_timer(&ifmgd->conn_mon_timer, round_jiffies_up(timeout));
 		return;
 	}