mac80211: when using iTXQ, select the queue in ieee80211_subif_start_xmit

When using iTXQ, the network stack does not need the real queue number, since
mac80211 is using its internal queues anyway. In that case we can defer
selecting the queue and remove a redundant station lookup in the tx path to save
some CPU cycles.
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/tx.c

@@ -3797,6 +3797,7 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
 				  u32 info_flags)
 {
 	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
+	struct ieee80211_local *local = sdata->local;
 	struct sta_info *sta;
 	struct sk_buff *next;
 
@@ -3810,7 +3811,15 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
 	if (ieee80211_lookup_ra_sta(sdata, skb, &sta))
 		goto out_free;
 
-	if (!IS_ERR_OR_NULL(sta)) {
+	if (IS_ERR(sta))
+		sta = NULL;
+
+	if (local->ops->wake_tx_queue) {
+		u16 queue = __ieee80211_select_queue(sdata, sta, skb);
+		skb_set_queue_mapping(skb, queue);
+	}
+
+	if (sta) {
 		struct ieee80211_fast_tx *fast_tx;
 
 		sk_pacing_shift_update(skb->sk, sdata->local->hw.tx_sk_pacing_shift);

net/mac80211/wme.c

@@ -141,6 +141,42 @@ u16 ieee80211_select_queue_80211(struct ieee80211_sub_if_data *sdata,
 	return ieee80211_downgrade_queue(sdata, NULL, skb);
 }
 
+u16 __ieee80211_select_queue(struct ieee80211_sub_if_data *sdata,
+			     struct sta_info *sta, struct sk_buff *skb)
+{
+	struct mac80211_qos_map *qos_map;
+	bool qos;
+
+	/* all mesh/ocb stations are required to support WME */
+	if (sdata->vif.type == NL80211_IFTYPE_MESH_POINT ||
+	    sdata->vif.type == NL80211_IFTYPE_OCB)
+		qos = true;
+	else if (sta)
+		qos = sta->sta.wme;
+	else
+		qos = false;
+
+	if (!qos) {
+		skb->priority = 0; /* required for correct WPA/11i MIC */
+		return IEEE80211_AC_BE;
+	}
+
+	if (skb->protocol == sdata->control_port_protocol) {
+		skb->priority = 7;
+		goto downgrade;
+	}
+
+	/* use the data classifier to determine what 802.1d tag the
+	 * data frame has */
+	qos_map = rcu_dereference(sdata->qos_map);
+	skb->priority = cfg80211_classify8021d(skb, qos_map ?
+					       &qos_map->qos_map : NULL);
+
+ downgrade:
+	return ieee80211_downgrade_queue(sdata, sta, skb);
+}
+
+
 /* Indicate which queue to use. */
 u16 ieee80211_select_queue(struct ieee80211_sub_if_data *sdata,
 			   struct sk_buff *skb)
@@ -148,10 +184,12 @@ u16 ieee80211_select_queue(struct ieee80211_sub_if_data *sdata,
 	struct ieee80211_local *local = sdata->local;
 	struct sta_info *sta = NULL;
 	const u8 *ra = NULL;
-	bool qos = false;
-	struct mac80211_qos_map *qos_map;
 	u16 ret;
 
+	/* when using iTXQ, we can do this later */
+	if (local->ops->wake_tx_queue)
+		return 0;
+
 	if (local->hw.queues < IEEE80211_NUM_ACS || skb->len < 6) {
 		skb->priority = 0; /* required for correct WPA/11i MIC */
 		return 0;
@@ -161,10 +199,8 @@ u16 ieee80211_select_queue(struct ieee80211_sub_if_data *sdata,
 	switch (sdata->vif.type) {
 	case NL80211_IFTYPE_AP_VLAN:
 		sta = rcu_dereference(sdata->u.vlan.sta);
-		if (sta) {
-			qos = sta->sta.wme;
+		if (sta)
 			break;
-		}
 		/* fall through */
 	case NL80211_IFTYPE_AP:
 		ra = skb->data;
@@ -172,56 +208,26 @@ u16 ieee80211_select_queue(struct ieee80211_sub_if_data *sdata,
 	case NL80211_IFTYPE_WDS:
 		ra = sdata->u.wds.remote_addr;
 		break;
-#ifdef CONFIG_MAC80211_MESH
-	case NL80211_IFTYPE_MESH_POINT:
-		qos = true;
-		break;
-#endif
 	case NL80211_IFTYPE_STATION:
 		/* might be a TDLS station */
 		sta = sta_info_get(sdata, skb->data);
 		if (sta)
-			qos = sta->sta.wme;
+			break;
 
 		ra = sdata->u.mgd.bssid;
 		break;
 	case NL80211_IFTYPE_ADHOC:
 		ra = skb->data;
 		break;
-	case NL80211_IFTYPE_OCB:
-		/* all stations are required to support WME */
-		qos = true;
-		break;
 	default:
 		break;
 	}
 
-	if (!sta && ra && !is_multicast_ether_addr(ra)) {
+	if (!sta && ra && !is_multicast_ether_addr(ra))
 		sta = sta_info_get(sdata, ra);
-		if (sta)
-			qos = sta->sta.wme;
-	}
-
-	if (!qos) {
-		skb->priority = 0; /* required for correct WPA/11i MIC */
-		ret = IEEE80211_AC_BE;
-		goto out;
-	}
-
-	if (skb->protocol == sdata->control_port_protocol) {
-		skb->priority = 7;
-		goto downgrade;
-	}
 
-	/* use the data classifier to determine what 802.1d tag the
-	 * data frame has */
-	qos_map = rcu_dereference(sdata->qos_map);
-	skb->priority = cfg80211_classify8021d(skb, qos_map ?
-					       &qos_map->qos_map : NULL);
+	ret = __ieee80211_select_queue(sdata, sta, skb);
 
- downgrade:
-	ret = ieee80211_downgrade_queue(sdata, sta, skb);
- out:
 	rcu_read_unlock();
 	return ret;
 }

net/mac80211/wme.h

@@ -16,6 +16,8 @@
 u16 ieee80211_select_queue_80211(struct ieee80211_sub_if_data *sdata,
 				 struct sk_buff *skb,
 				 struct ieee80211_hdr *hdr);
+u16 __ieee80211_select_queue(struct ieee80211_sub_if_data *sdata,
+			     struct sta_info *sta, struct sk_buff *skb);
 u16 ieee80211_select_queue(struct ieee80211_sub_if_data *sdata,
 			   struct sk_buff *skb);
 void ieee80211_set_qos_hdr(struct ieee80211_sub_if_data *sdata,