mac80211: synchronously reserve TID per station

In TDLS (e.g., TDLS off-channel) there is a requirement for
some drivers to supply an unused TID between the AP and the
device to the FW, to allow sending PTI requests and to allow
the FW to aggregate on a specific TID for better throughput.

To ensure that the allocated TID is indeed unused, this patch
introduces an API for blocking the driver from TXing on that
TID.

Signed-off-by: Liad Kaufman <liad.kaufman@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 91 insertions, 0 deletions

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 2dd89670e1cd..0cb41d1a1f20 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -3107,6 +3107,97 @@ ieee80211_get_buffered_bc(struct ieee80211_hw *hw,
 }
 EXPORT_SYMBOL(ieee80211_get_buffered_bc);
 
+int ieee80211_reserve_tid(struct ieee80211_sta *pubsta, u8 tid)
+{
+	struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
+	struct ieee80211_sub_if_data *sdata = sta->sdata;
+	struct ieee80211_local *local = sdata->local;
+	int ret;
+	u32 queues;
+
+	lockdep_assert_held(&local->sta_mtx);
+
+	/* only some cases are supported right now */
+	switch (sdata->vif.type) {
+	case NL80211_IFTYPE_STATION:
+	case NL80211_IFTYPE_AP:
+	case NL80211_IFTYPE_AP_VLAN:
+		break;
+	default:
+		WARN_ON(1);
+		return -EINVAL;
+	}
+
+	if (WARN_ON(tid >= IEEE80211_NUM_UPS))
+		return -EINVAL;
+
+	if (sta->reserved_tid == tid) {
+		ret = 0;
+		goto out;
+	}
+
+	if (sta->reserved_tid != IEEE80211_TID_UNRESERVED) {
+		sdata_err(sdata, "TID reservation already active\n");
+		ret = -EALREADY;
+		goto out;
+	}
+
+	ieee80211_stop_vif_queues(sdata->local, sdata,
+				  IEEE80211_QUEUE_STOP_REASON_RESERVE_TID);
+
+	synchronize_net();
+
+	/* Tear down BA sessions so we stop aggregating on this TID */
+	if (local->hw.flags & IEEE80211_HW_AMPDU_AGGREGATION) {
+		set_sta_flag(sta, WLAN_STA_BLOCK_BA);
+		__ieee80211_stop_tx_ba_session(sta, tid,
+					       AGG_STOP_LOCAL_REQUEST);
+	}
+
+	queues = BIT(sdata->vif.hw_queue[ieee802_1d_to_ac[tid]]);
+	__ieee80211_flush_queues(local, sdata, queues);
+
+	sta->reserved_tid = tid;
+
+	ieee80211_wake_vif_queues(local, sdata,
+				  IEEE80211_QUEUE_STOP_REASON_RESERVE_TID);
+
+	if (local->hw.flags & IEEE80211_HW_AMPDU_AGGREGATION)
+		clear_sta_flag(sta, WLAN_STA_BLOCK_BA);
+
+	ret = 0;
+ out:
+	return ret;
+}
+EXPORT_SYMBOL(ieee80211_reserve_tid);
+
+void ieee80211_unreserve_tid(struct ieee80211_sta *pubsta, u8 tid)
+{
+	struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
+	struct ieee80211_sub_if_data *sdata = sta->sdata;
+
+	lockdep_assert_held(&sdata->local->sta_mtx);
+
+	/* only some cases are supported right now */
+	switch (sdata->vif.type) {
+	case NL80211_IFTYPE_STATION:
+	case NL80211_IFTYPE_AP:
+	case NL80211_IFTYPE_AP_VLAN:
+		break;
+	default:
+		WARN_ON(1);
+		return;
+	}
+
+	if (tid != sta->reserved_tid) {
+		sdata_err(sdata, "TID to unreserve (%d) isn't reserved\n", tid);
+		return;
+	}
+
+	sta->reserved_tid = IEEE80211_TID_UNRESERVED;
+}
+EXPORT_SYMBOL(ieee80211_unreserve_tid);
+
 void __ieee80211_tx_skb_tid_band(struct ieee80211_sub_if_data *sdata,
 				 struct sk_buff *skb, int tid,
 				 enum ieee80211_band band)