wl12xx: avoid blocking while holding rcu lock on bss info change

Some blocking functions were called while holding the rcu lock for
accessing STA information. This can lead to a deadlock.

Save the required info beforehand and release the rcu without
blocking.
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>

drivers/net/wireless/wl12xx/main.c

@@ -2222,6 +2222,8 @@ static void wl1271_bss_info_changed_sta(struct wl1271 *wl,
 	u32 sta_rate_set = 0;
 	int ret;
 	struct ieee80211_sta *sta;
+	bool sta_exists = false;
+	struct ieee80211_sta_ht_cap sta_ht_cap;
 
 	if (is_ibss) {
 		ret = wl1271_bss_beacon_info_changed(wl, vif, bss_conf,
@@ -2293,16 +2295,20 @@ static void wl1271_bss_info_changed_sta(struct wl1271 *wl,
 		if (sta->ht_cap.ht_supported)
 			sta_rate_set |=
 			    (sta->ht_cap.mcs.rx_mask[0] << HW_HT_RATES_OFFSET);
+		sta_ht_cap = sta->ht_cap;
+		sta_exists = true;
+	}
+	rcu_read_unlock();
 
+	if (sta_exists) {
 		/* handle new association with HT and HT information change */
 		if ((changed & BSS_CHANGED_HT) &&
 		    (bss_conf->channel_type != NL80211_CHAN_NO_HT)) {
-			ret = wl1271_acx_set_ht_capabilities(wl, &sta->ht_cap,
+			ret = wl1271_acx_set_ht_capabilities(wl, &sta_ht_cap,
 							     true);
 			if (ret < 0) {
 				wl1271_warning("Set ht cap true failed %d",
 					       ret);
-				rcu_read_unlock();
 				goto out;
 			}
 			ret = wl1271_acx_set_ht_information(wl,
@@ -2310,23 +2316,20 @@ static void wl1271_bss_info_changed_sta(struct wl1271 *wl,
 			if (ret < 0) {
 				wl1271_warning("Set ht information failed %d",
 					       ret);
-				rcu_read_unlock();
 				goto out;
 			}
 		}
 		/* handle new association without HT and disassociation */
 		else if (changed & BSS_CHANGED_ASSOC) {
-			ret = wl1271_acx_set_ht_capabilities(wl, &sta->ht_cap,
+			ret = wl1271_acx_set_ht_capabilities(wl, &sta_ht_cap,
 							     false);
 			if (ret < 0) {
 				wl1271_warning("Set ht cap false failed %d",
 					       ret);
-				rcu_read_unlock();
 				goto out;
 			}
 		}
 	}
-	rcu_read_unlock();
 
 	if ((changed & BSS_CHANGED_ASSOC)) {
 		if (bss_conf->assoc) {