mac80211: simplify TX aggregation start

There really is no need to make drivers call the
ieee80211_start_tx_ba_cb_irqsafe() function and then
schedule the worker if all we want is to set a bit.

Add a new return value (that was previously considered
invalid) to indicate that the driver is immediately
ready for the session, and make drivers use it. The
only drivers that remain different are the Intel ones
as they need to negotiate more with the firmware.

Link: https://lore.kernel.org/r/1570007543-I152912660131cbab2e5d80b4218238c20f8a06e5@changeid
Signed-off-by: Johannes Berg <[e-mail]>

drivers/net/wireless/ath/ath9k/htc_drv_main.c

···
 	case IEEE80211_AMPDU_TX_START:
 		ret = ath9k_htc_tx_aggr_oper(priv, vif, sta, action, tid);
 		if (!ret)
-			ieee80211_start_tx_ba_cb_irqsafe(vif, sta->addr, tid);
+			ret = IEEE80211_AMPDU_TX_START_IMMEDIATE;
 		break;
 	case IEEE80211_AMPDU_TX_STOP_CONT:
 	case IEEE80211_AMPDU_TX_STOP_FLUSH:

drivers/net/wireless/ath/ath9k/main.c

···
 		ath9k_ps_wakeup(sc);
 		ret = ath_tx_aggr_start(sc, sta, tid, ssn);
 		if (!ret)
-			ieee80211_start_tx_ba_cb_irqsafe(vif, sta->addr, tid);
+			ret = IEEE80211_AMPDU_TX_START_IMMEDIATE;
 		ath9k_ps_restore(sc);
 		break;
 	case IEEE80211_AMPDU_TX_STOP_FLUSH:

drivers/net/wireless/ath/carl9170/main.c

···
 		rcu_assign_pointer(sta_info->agg[tid], tid_info);
 		spin_unlock_bh(&ar->tx_ampdu_list_lock);
 
-		ieee80211_start_tx_ba_cb_irqsafe(vif, sta->addr, tid);
-		break;
+		return IEEE80211_AMPDU_TX_START_IMMEDIATE;
 
 	case IEEE80211_AMPDU_TX_STOP_CONT:
 	case IEEE80211_AMPDU_TX_STOP_FLUSH:

drivers/net/wireless/ath/wcn36xx/main.c

···
 	enum ieee80211_ampdu_mlme_action action = params->action;
 	u16 tid = params->tid;
 	u16 *ssn = &params->ssn;
+	int ret = 0;
 
 	wcn36xx_dbg(WCN36XX_DBG_MAC, "mac ampdu action action %d tid %d\n",
 		    action, tid);
···
 		sta_priv->ampdu_state[tid] = WCN36XX_AMPDU_START;
 		spin_unlock_bh(&sta_priv->ampdu_lock);
 
-		ieee80211_start_tx_ba_cb_irqsafe(vif, sta->addr, tid);
+		ret = IEEE80211_AMPDU_TX_START_IMMEDIATE;
 		break;
 	case IEEE80211_AMPDU_TX_OPERATIONAL:
 		spin_lock_bh(&sta_priv->ampdu_lock);
···
 
 	mutex_unlock(&wcn->conf_mutex);
 
-	return 0;
+	return ret;
 }
 
 static const struct ieee80211_ops wcn36xx_ops = {

drivers/net/wireless/broadcom/brcm80211/brcmsmac/mac80211_if.c

···
 				     "START: tid %d is not agg\'able\n", tid);
 			return -EINVAL;
 		}
-		ieee80211_start_tx_ba_cb_irqsafe(vif, sta->addr, tid);
-		break;
+		return IEEE80211_AMPDU_TX_START_IMMEDIATE;
 
 	case IEEE80211_AMPDU_TX_STOP_CONT:
 	case IEEE80211_AMPDU_TX_STOP_FLUSH:

drivers/net/wireless/intel/iwlegacy/4965-mac.c

···
 	if (tid_data->tfds_in_queue == 0) {
 		D_HT("HW queue is empty\n");
 		tid_data->agg.state = IL_AGG_ON;
-		ieee80211_start_tx_ba_cb_irqsafe(vif, sta->addr, tid);
+		ret = IEEE80211_AMPDU_TX_START_IMMEDIATE;
 	} else {
 		D_HT("HW queue is NOT empty: %d packets in HW queue\n",
 		     tid_data->tfds_in_queue);

drivers/net/wireless/intel/iwlwifi/dvm/tx.c

···
 		IWL_DEBUG_TX_QUEUES(priv, "Can proceed: ssn = next_recl = %d\n",
 				    tid_data->agg.ssn);
 		tid_data->agg.state = IWL_AGG_STARTING;
-		ieee80211_start_tx_ba_cb_irqsafe(vif, sta->addr, tid);
+		ret = IEEE80211_AMPDU_TX_START_IMMEDIATE;
 	} else {
 		IWL_DEBUG_TX_QUEUES(priv, "Can't proceed: ssn %d, "
 				    "next_reclaimed = %d\n",

drivers/net/wireless/intel/iwlwifi/mvm/sta.c

···
 
 	if (normalized_ssn == tid_data->next_reclaimed) {
 		tid_data->state = IWL_AGG_STARTING;
-		ieee80211_start_tx_ba_cb_irqsafe(vif, sta->addr, tid);
+		ret = IEEE80211_AMPDU_TX_START_IMMEDIATE;
 	} else {
 		tid_data->state = IWL_EMPTYING_HW_QUEUE_ADDBA;
+		ret = 0;
 	}
-
-	ret = 0;
 
 out:
 	spin_unlock_bh(&mvmsta->lock);

drivers/net/wireless/mac80211_hwsim.c

···
 
 	switch (action) {
 	case IEEE80211_AMPDU_TX_START:
-		ieee80211_start_tx_ba_cb_irqsafe(vif, sta->addr, tid);
-		break;
+		return IEEE80211_AMPDU_TX_START_IMMEDIATE;
 	case IEEE80211_AMPDU_TX_STOP_CONT:
 	case IEEE80211_AMPDU_TX_STOP_FLUSH:
 	case IEEE80211_AMPDU_TX_STOP_FLUSH_CONT:

drivers/net/wireless/marvell/mwl8k.c

···
 			rc = -EBUSY;
 			break;
 		}
-		ieee80211_start_tx_ba_cb_irqsafe(vif, addr, tid);
+		rc = IEEE80211_AMPDU_TX_START_IMMEDIATE;
 		break;
 	case IEEE80211_AMPDU_TX_STOP_CONT:
 	case IEEE80211_AMPDU_TX_STOP_FLUSH:

drivers/net/wireless/mediatek/mt76/mt7603/main.c

···
 		break;
 	case IEEE80211_AMPDU_TX_START:
 		mtxq->agg_ssn = IEEE80211_SN_TO_SEQ(ssn);
-		ieee80211_start_tx_ba_cb_irqsafe(vif, sta->addr, tid);
-		break;
+		return IEEE80211_AMPDU_TX_START_IMMEDIATE;
 	case IEEE80211_AMPDU_TX_STOP_CONT:
 		mtxq->aggr = false;
 		mt7603_mac_tx_ba_reset(dev, msta->wcid.idx, tid, -1);

drivers/net/wireless/mediatek/mt76/mt7615/main.c

···
 		break;
 	case IEEE80211_AMPDU_TX_START:
 		mtxq->agg_ssn = IEEE80211_SN_TO_SEQ(ssn);
-		ieee80211_start_tx_ba_cb_irqsafe(vif, sta->addr, tid);
-		break;
+		return IEEE80211_AMPDU_TX_START_IMMEDIATE;
 	case IEEE80211_AMPDU_TX_STOP_CONT:
 		mtxq->aggr = false;
 		mt7615_mcu_set_tx_ba(dev, params, 0);

drivers/net/wireless/mediatek/mt76/mt76x02_util.c

···
 		break;
 	case IEEE80211_AMPDU_TX_START:
 		mtxq->agg_ssn = IEEE80211_SN_TO_SEQ(ssn);
-		ieee80211_start_tx_ba_cb_irqsafe(vif, sta->addr, tid);
-		break;
+		return IEEE80211_AMPDU_TX_START_IMMEDIATE;
 	case IEEE80211_AMPDU_TX_STOP_CONT:
 		mtxq->aggr = false;
 		ieee80211_stop_tx_ba_cb_irqsafe(vif, sta->addr, tid);

drivers/net/wireless/mediatek/mt7601u/main.c

···
 		break;
 	case IEEE80211_AMPDU_TX_START:
 		msta->agg_ssn[tid] = ssn << 4;
-		ieee80211_start_tx_ba_cb_irqsafe(vif, sta->addr, tid);
-		break;
+		return IEEE80211_AMPDU_TX_START_IMMEDIATE;
 	case IEEE80211_AMPDU_TX_STOP_CONT:
 		ieee80211_stop_tx_ba_cb_irqsafe(vif, sta->addr, tid);
 		break;

drivers/net/wireless/ralink/rt2x00/rt2800lib.c

···
 	 * when the hw reorders frames due to aggregation.
 	 */
 	if (sta_priv->wcid > WCID_END)
-		return 1;
+		return -ENOSPC;
 
 	switch (action) {
 	case IEEE80211_AMPDU_RX_START:
···
 		 */
 		break;
 	case IEEE80211_AMPDU_TX_START:
-		ieee80211_start_tx_ba_cb_irqsafe(vif, sta->addr, tid);
+		ret = IEEE80211_AMPDU_TX_START_IMMEDIATE;
 		break;
 	case IEEE80211_AMPDU_TX_STOP_CONT:
 	case IEEE80211_AMPDU_TX_STOP_FLUSH:

drivers/net/wireless/realtek/rtlwifi/base.c

···
 
 	tid_data->agg.agg_state = RTL_AGG_START;
 
-	ieee80211_start_tx_ba_cb_irqsafe(vif, sta->addr, tid);
-	return 0;
+	return IEEE80211_AMPDU_TX_START_IMMEDIATE;
 }
 
 int rtl_tx_agg_stop(struct ieee80211_hw *hw, struct ieee80211_vif *vif,

drivers/net/wireless/realtek/rtw88/mac80211.c

···
 
 	switch (params->action) {
 	case IEEE80211_AMPDU_TX_START:
-		ieee80211_start_tx_ba_cb_irqsafe(vif, sta->addr, tid);
-		break;
+		return IEEE80211_AMPDU_TX_START_IMMEDIATE;
 	case IEEE80211_AMPDU_TX_STOP_CONT:
 	case IEEE80211_AMPDU_TX_STOP_FLUSH:
 	case IEEE80211_AMPDU_TX_STOP_FLUSH_CONT:

drivers/net/wireless/rsi/rsi_91x_mac80211.c

···
 		else if ((vif->type == NL80211_IFTYPE_AP) ||
 			 (vif->type == NL80211_IFTYPE_P2P_GO))
 			rsta->seq_start[tid] = seq_no;
-		ieee80211_start_tx_ba_cb_irqsafe(vif, sta->addr, tid);
-		status = 0;
+		status = IEEE80211_AMPDU_TX_START_IMMEDIATE;
 		break;
 
 	case IEEE80211_AMPDU_TX_STOP_CONT:

include/net/mac80211.h

···
  *
  * @IEEE80211_AMPDU_RX_START: start RX aggregation
  * @IEEE80211_AMPDU_RX_STOP: stop RX aggregation
- * @IEEE80211_AMPDU_TX_START: start TX aggregation
+ * @IEEE80211_AMPDU_TX_START: start TX aggregation, the driver must either
+ *	call ieee80211_start_tx_ba_cb_irqsafe() or return the special
+ *	status %IEEE80211_AMPDU_TX_START_IMMEDIATE.
  * @IEEE80211_AMPDU_TX_OPERATIONAL: TX aggregation has become operational
  * @IEEE80211_AMPDU_TX_STOP_CONT: stop TX aggregation but continue transmitting
  *	queued packets, now unaggregated. After all packets are transmitted the
···
 	IEEE80211_AMPDU_TX_STOP_FLUSH_CONT,
 	IEEE80211_AMPDU_TX_OPERATIONAL,
 };
+
+#define IEEE80211_AMPDU_TX_START_IMMEDIATE 1
 
 /**
  * struct ieee80211_ampdu_params - AMPDU action parameters
···
 	 *
 	 * Even ``189`` would be wrong since 1 could be lost again.
 	 *
-	 * Returns a negative error code on failure.
+	 * Returns a negative error code on failure. The driver may return
+	 * %IEEE80211_AMPDU_TX_START_IMMEDIATE for %IEEE80211_AMPDU_TX_START
+	 * if the session can start immediately.
+	 *
 	 * The callback can sleep.
 	 */
 	int (*ampdu_action)(struct ieee80211_hw *hw,

net/mac80211/agg-tx.c

···
 
 	params.ssn = sta->tid_seq[tid] >> 4;
 	ret = drv_ampdu_action(local, sdata, &params);
-	if (ret) {
+	if (ret == IEEE80211_AMPDU_TX_START_IMMEDIATE) {
+		/*
+		 * We didn't send the request yet, so don't need to check
+		 * here if we already got a response, just mark as driver
+		 * ready immediately.
+		 */
+		set_bit(HT_AGG_STATE_DRV_READY, &tid_tx->state);
+	} else if (ret) {
 		ht_dbg(sdata,
 		       "BA request denied - HW unavailable for %pM tid %d\n",
 		       sta->sta.addr, tid);