mac80211: reduce the number of retries for nullfunc probing

Since nullfunc frames are transmitted as unicast frames, they're more
reliable than the broadcast probe requests, so we need fewer retries
to figure out whether the AP is really gone.
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/mlme.c

@@ -28,6 +28,7 @@
 #include "rate.h"
 #include "led.h"
 
+#define IEEE80211_MAX_NULLFUNC_TRIES 2
 #define IEEE80211_MAX_PROBE_TRIES 5
 
 /*
@@ -1924,9 +1925,15 @@ void ieee80211_sta_work(struct ieee80211_sub_if_data *sdata)
 			    IEEE80211_STA_CONNECTION_POLL) &&
 	    ifmgd->associated) {
 		u8 bssid[ETH_ALEN];
+		int max_tries;
 
 		memcpy(bssid, ifmgd->associated->bssid, ETH_ALEN);
 
+		if (local->hw.flags & IEEE80211_HW_REPORTS_TX_ACK_STATUS)
+			max_tries = IEEE80211_MAX_NULLFUNC_TRIES;
+		else
+			max_tries = IEEE80211_MAX_PROBE_TRIES;
+
 		/* ACK received for nullfunc probing frame */
 		if (!ifmgd->probe_send_count)
 			ieee80211_reset_ap_probe(sdata);
@@ -1934,7 +1941,7 @@ void ieee80211_sta_work(struct ieee80211_sub_if_data *sdata)
 		else if (time_is_after_jiffies(ifmgd->probe_timeout))
 			run_again(ifmgd, ifmgd->probe_timeout);
 
-		else if (ifmgd->probe_send_count < IEEE80211_MAX_PROBE_TRIES) {
+		else if (ifmgd->probe_send_count < max_tries) {
 #ifdef CONFIG_MAC80211_VERBOSE_DEBUG
 			wiphy_debug(local->hw.wiphy,
 				    "%s: No probe response from AP %pM"