mac80211: Add new sta_info getter by sta/vif addrs

In ieee80211_tx_status() we don't have an sdata struct when looking up the
destination sta. Instead, we just do a lookup by the vif addr that is the
source of the packet being completed. Factor this out into a new sta_info
getter helper, since we need to use it for accounting AQL as well.
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20191112130835.382062-1-toke@redhat.com
[remove internal rcu_read_lock(), document instead]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/sta_info.c

@@ -210,6 +210,20 @@ struct sta_info *sta_info_get_bss(struct ieee80211_sub_if_data *sdata,
 	return NULL;
 }
 
+struct sta_info *sta_info_get_by_addrs(struct ieee80211_local *local,
+				       const u8 *sta_addr, const u8 *vif_addr)
+{
+	struct rhlist_head *tmp;
+	struct sta_info *sta;
+
+	for_each_sta_info(local, sta_addr, sta, tmp) {
+		if (ether_addr_equal(vif_addr, sta->sdata->vif.addr))
+			return sta;
+	}
+
+	return NULL;
+}
+
 struct sta_info *sta_info_get_by_idx(struct ieee80211_sub_if_data *sdata,
 				     int idx)
 {

net/mac80211/sta_info.h

@@ -725,6 +725,10 @@ struct sta_info *sta_info_get(struct ieee80211_sub_if_data *sdata,
 struct sta_info *sta_info_get_bss(struct ieee80211_sub_if_data *sdata,
 				  const u8 *addr);
 
+/* user must hold sta_mtx or be in RCU critical section */
+struct sta_info *sta_info_get_by_addrs(struct ieee80211_local *local,
+				       const u8 *sta_addr, const u8 *vif_addr);
+
 #define for_each_sta_info(local, _addr, _sta, _tmp)			\
 	rhl_for_each_entry_rcu(_sta, _tmp,				\
 			       sta_info_hash_lookup(local, _addr), hash_node)

net/mac80211/status.c

@@ -1073,19 +1073,13 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb)
 		.skb = skb,
 		.info = IEEE80211_SKB_CB(skb),
 	};
-	struct rhlist_head *tmp;
 	struct sta_info *sta;
 
 	rcu_read_lock();
 
-	for_each_sta_info(local, hdr->addr1, sta, tmp) {
-		/* skip wrong virtual interface */
-		if (!ether_addr_equal(hdr->addr2, sta->sdata->vif.addr))
-			continue;
-
+	sta = sta_info_get_by_addrs(local, hdr->addr1, hdr->addr2);
+	if (sta)
 		status.sta = &sta->sta;
-		break;
-	}
 
 	__ieee80211_tx_status(hw, &status);
 	rcu_read_unlock();