Improve the beacon miss handling. Instead of just dropping the connection,
send a directed probe request to the AP to see if it's still responding.
Schedule a software beacon miss timer in this case, which adds a timeout
for the APs probe response.

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

--- a/net80211/ieee80211_input.c
+++ b/net80211/ieee80211_input.c
@@ -3398,12 +3398,17 @@
 			}
 
 			/* WDS/Repeater: re-schedule software beacon timer for 
-			 * STA. */
-			if ((vap->iv_state == IEEE80211_S_RUN) &&
-			    (vap->iv_flags_ext & IEEE80211_FEXT_SWBMISS)) {
-				mod_timer(&vap->iv_swbmiss, 
+			 * STA. Reset consecutive bmiss counter as well */
+			IEEE80211_LOCK_IRQ(ic);
+			if (vap->iv_state == IEEE80211_S_RUN) {
+				vap->iv_bmiss_count = 0;
+				if (vap->iv_flags_ext & IEEE80211_FEXT_SWBMISS)
+					mod_timer(&vap->iv_swbmiss,
 						jiffies + vap->iv_swbmiss_period);
+				else
+					del_timer(&vap->iv_swbmiss);
 			}
+			IEEE80211_UNLOCK_IRQ(ic);
 
 			/* If scanning, pass the info to the scan module.
 			 * Otherwise, check if it's the right time to do
--- a/net80211/ieee80211_proto.c
+++ b/net80211/ieee80211_proto.c
@@ -1209,6 +1209,8 @@
 	}
 	/* XXX locking */
 	TAILQ_FOREACH(vap, &ic->ic_vaps, iv_next) {
+		int count;
+
 		IEEE80211_DPRINTF(vap,
 			IEEE80211_MSG_STATE | IEEE80211_MSG_DEBUG,
 			"%s\n", "beacon miss");
@@ -1221,6 +1223,29 @@
 		if (vap->iv_opmode != IEEE80211_M_STA ||
 		    vap->iv_state != IEEE80211_S_RUN)
 			continue;
+
+		IEEE80211_LOCK_IRQ(ic);
+		count = vap->iv_bmiss_count++;
+		if (count) {
+			/* if the counter was already above zero, reset it
+			 * here, since we're going to do the bmiss handling
+			 * in any case */
+			vap->iv_bmiss_count = 0;
+		} else {
+			/* schedule the software beacon miss timer, it will be
+			 * cancelled, if the probe request is acked */
+			mod_timer(&vap->iv_swbmiss, jiffies + vap->iv_swbmiss_period);
+		}
+		IEEE80211_UNLOCK_IRQ(ic);
+
+		if (!count) {
+			ieee80211_send_probereq(vap->iv_bss, vap->iv_myaddr,
+				vap->iv_bss->ni_bssid, vap->iv_bss->ni_bssid,
+				vap->iv_bss->ni_essid, vap->iv_bss->ni_esslen,
+				NULL, 0);
+			continue;
+		}
+
 		if (ic->ic_roaming == IEEE80211_ROAMING_AUTO) {
 #ifdef ATH_SUPERG_DYNTURBO
 			/* 
@@ -1617,14 +1642,14 @@
 		}
 
 		/* WDS/Repeater: Start software beacon timer for STA */
+		vap->iv_swbmiss.function = ieee80211_sta_swbmiss;
+		vap->iv_swbmiss.data = (unsigned long) vap;
+		vap->iv_swbmiss_period = IEEE80211_TU_TO_JIFFIES(
+			vap->iv_ic->ic_bmissthreshold * ni->ni_intval);
+
 		if (ostate != IEEE80211_S_RUN &&
 		    (vap->iv_opmode == IEEE80211_M_STA &&
 		     vap->iv_flags_ext & IEEE80211_FEXT_SWBMISS)) {
-			vap->iv_swbmiss.function = ieee80211_sta_swbmiss;
-			vap->iv_swbmiss.data = (unsigned long) vap;
-			vap->iv_swbmiss_period = IEEE80211_TU_TO_JIFFIES(
-				vap->iv_ic->ic_bmissthreshold * ni->ni_intval);
-
 			mod_timer(&vap->iv_swbmiss, jiffies + vap->iv_swbmiss_period);
 		}
 
--- a/net80211/ieee80211_var.h
+++ b/net80211/ieee80211_var.h
@@ -282,6 +282,7 @@
 
 	struct timer_list iv_swbmiss;			/* software beacon miss timer */
 	u_int16_t iv_swbmiss_period; 			/* software beacon miss timer period */
+	u_int16_t iv_bmiss_count;			/* consecutive beacon miss counter */
 	struct ieee80211_nsparams iv_nsparams;		/* new state parameters for tasklet for stajoin1 */
 	struct IEEE80211_TQ_STRUCT iv_stajoin1tq; 	/* tasklet for newstate action called from stajoin1tq */
 	unsigned int iv_nsdone;				/* Done with scheduled newstate tasklet */