--- /dev/null
+From: Felix Fietkau <nbd@openwrt.org>
+Date: Tue, 18 Nov 2014 23:58:51 +0100
+Subject: [PATCH] mac80211: add an intermediate software queue implementation
+
+This allows drivers to request per-vif and per-sta-tid queues from which
+they can pull frames. This makes it easier to keep the hardware queues
+short, and to improve fairness between clients and vifs.
+
+The task of scheduling packet transmission is left up to the driver -
+queueing is controlled by mac80211. Drivers can only dequeue packets by
+calling ieee80211_tx_dequeue. This makes it possible to add active queue
+management later without changing drivers using this code.
+
+This can also be used as a starting point to implement A-MSDU
+aggregation in a way that does not add artificially induced latency.
+
+Signed-off-by: Felix Fietkau <nbd@openwrt.org>
+---
+
+--- a/include/net/mac80211.h
++++ b/include/net/mac80211.h
+@@ -1192,6 +1192,8 @@ struct ieee80211_vif {
+ u8 cab_queue;
+ u8 hw_queue[IEEE80211_NUM_ACS];
+
++ struct ieee80211_txq *txq;
++
+ struct ieee80211_chanctx_conf __rcu *chanctx_conf;
+
+ u32 driver_flags;
+@@ -1448,6 +1450,8 @@ struct ieee80211_sta {
+ bool tdls;
+ bool tdls_initiator;
+
++ struct ieee80211_txq *txq[IEEE80211_NUM_TIDS];
++
+ /* must be last */
+ u8 drv_priv[0] __aligned(sizeof(void *));
+ };
+@@ -1476,6 +1480,27 @@ struct ieee80211_tx_control {
+ };
+
+ /**
++ * struct ieee80211_txq - Software intermediate tx queue
++ *
++ * @vif: &struct ieee80211_vif pointer from the add_interface callback.
++ * @sta: station table entry, may be NULL for per-vif queue
++ * @tid: the TID for this queue (unset for per-vif queue)
++ * @ac: the AC for this queue
++ *
++ * The driver can obtain packets from this queue by calling
++ * ieee80211_tx_dequeue().
++ */
++struct ieee80211_txq {
++ struct ieee80211_vif *vif;
++ struct ieee80211_sta *sta;
++ u8 tid;
++ u8 ac;
++
++ /* must be last */
++ u8 drv_priv[0] __aligned(sizeof(void *));
++};
++
++/**
+ * enum ieee80211_hw_flags - hardware flags
+ *
+ * These flags are used to indicate hardware capabilities to
+@@ -1698,6 +1723,8 @@ enum ieee80211_hw_flags {
+ * within &struct ieee80211_sta.
+ * @chanctx_data_size: size (in bytes) of the drv_priv data area
+ * within &struct ieee80211_chanctx_conf.
++ * @txq_data_size: size (in bytes) of the drv_priv data area
++ * within @struct ieee80211_txq.
+ *
+ * @max_rates: maximum number of alternate rate retry stages the hw
+ * can handle.
+@@ -1746,6 +1773,9 @@ enum ieee80211_hw_flags {
+ * @n_cipher_schemes: a size of an array of cipher schemes definitions.
+ * @cipher_schemes: a pointer to an array of cipher scheme definitions
+ * supported by HW.
++ *
++ * @txq_ac_max_pending: maximum number of frames per AC pending in all txq
++ * entries for a vif.
+ */
+ struct ieee80211_hw {
+ struct ieee80211_conf conf;
+@@ -1758,6 +1788,7 @@ struct ieee80211_hw {
+ int vif_data_size;
+ int sta_data_size;
+ int chanctx_data_size;
++ int txq_data_size;
+ u16 queues;
+ u16 max_listen_interval;
+ s8 max_signal;
+@@ -1774,6 +1805,7 @@ struct ieee80211_hw {
+ u8 uapsd_max_sp_len;
+ u8 n_cipher_schemes;
+ const struct ieee80211_cipher_scheme *cipher_schemes;
++ int txq_ac_max_pending;
+ };
+
+ /**
+@@ -2881,6 +2913,8 @@ enum ieee80211_reconfig_type {
+ *
+ * @get_txpower: get current maximum tx power (in dBm) based on configuration
+ * and hardware limits.
++ *
++ * @wake_tx_queue: Called when new packets have been added to the queue.
+ */
+ struct ieee80211_ops {
+ void (*tx)(struct ieee80211_hw *hw,
+@@ -3095,6 +3129,9 @@ struct ieee80211_ops {
+ u32 (*get_expected_throughput)(struct ieee80211_sta *sta);
+ int (*get_txpower)(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
+ int *dbm);
++
++ void (*wake_tx_queue)(struct ieee80211_hw *hw,
++ struct ieee80211_txq *txq);
+ };
+
+ /**
+@@ -5038,4 +5075,17 @@ void ieee80211_tdls_oper_request(struct
+ */
+ size_t ieee80211_ie_split(const u8 *ies, size_t ielen,
+ const u8 *ids, int n_ids, size_t offset);
++
++/**
++ * ieee80211_tx_dequeue - dequeue a packet from a software tx queue
++ *
++ * @hw: pointer as obtained from ieee80211_alloc_hw()
++ * @txq: pointer obtained from .add_tx_queue() call
++ *
++ * Returns 0 if successful, -EAGAIN if no frame was available.
++ */
++int ieee80211_tx_dequeue(struct ieee80211_hw *hw, struct ieee80211_txq *txq,
++ struct sk_buff **skb);
++
++
+ #endif /* MAC80211_H */
+--- a/net/mac80211/driver-ops.h
++++ b/net/mac80211/driver-ops.h
+@@ -1311,4 +1311,21 @@ static inline int drv_get_txpower(struct
+ return ret;
+ }
+
++static inline void drv_wake_tx_queue(struct ieee80211_local *local,
++ struct txq_info *txq)
++{
++ struct ieee80211_sub_if_data *sdata = vif_to_sdata(txq->txq.vif);
++
++ if (!check_sdata_in_driver(sdata))
++ return;
++
++ if (txq->txq.sta)
++ trace_drv_wake_sta_tx_queue(local, sdata, txq->txq.sta,
++ txq->txq.tid);
++ else
++ trace_drv_wake_vif_tx_queue(local, sdata);
++
++ local->ops->wake_tx_queue(&local->hw, &txq->txq);
++}
++
+ #endif /* __MAC80211_DRIVER_OPS */
+--- a/net/mac80211/ieee80211_i.h
++++ b/net/mac80211/ieee80211_i.h
+@@ -793,6 +793,13 @@ struct mac80211_qos_map {
+ struct rcu_head rcu_head;
+ };
+
++struct txq_info {
++ struct sk_buff_head queue;
++
++ /* keep last! */
++ struct ieee80211_txq txq;
++};
++
+ struct ieee80211_sub_if_data {
+ struct list_head list;
+
+@@ -837,6 +844,8 @@ struct ieee80211_sub_if_data {
+ bool control_port_no_encrypt;
+ int encrypt_headroom;
+
++ struct txq_info *txq;
++ atomic_t txq_len[IEEE80211_NUM_ACS];
+ struct ieee80211_tx_queue_params tx_conf[IEEE80211_NUM_ACS];
+ struct mac80211_qos_map __rcu *qos_map;
+
+@@ -1868,6 +1877,11 @@ void ieee80211_add_pending_skbs(struct i
+ struct sk_buff_head *skbs);
+ void ieee80211_flush_queues(struct ieee80211_local *local,
+ struct ieee80211_sub_if_data *sdata);
++void ieee80211_init_tx_queue(struct ieee80211_sub_if_data *sdata,
++ struct sta_info *sta,
++ struct txq_info *txq, int tid);
++void ieee80211_flush_tx_queue(struct ieee80211_local *local,
++ struct ieee80211_txq *txq);
+
+ void ieee80211_send_auth(struct ieee80211_sub_if_data *sdata,
+ u16 transaction, u16 auth_alg, u16 status,
+--- a/net/mac80211/iface.c
++++ b/net/mac80211/iface.c
+@@ -967,6 +967,9 @@ static void ieee80211_do_stop(struct iee
+ }
+ spin_unlock_irqrestore(&local->queue_stop_reason_lock, flags);
+
++ if (sdata->vif.txq)
++ ieee80211_flush_tx_queue(local, sdata->vif.txq);
++
+ if (local->open_count == 0)
+ ieee80211_clear_tx_pending(local);
+
+@@ -1773,6 +1776,13 @@ int ieee80211_if_add(struct ieee80211_lo
+ /* setup type-dependent data */
+ ieee80211_setup_sdata(sdata, type);
+
++ if (local->ops->wake_tx_queue) {
++ sdata->txq = kzalloc(sizeof(*sdata->txq) +
++ local->hw.txq_data_size, GFP_KERNEL);
++ if (sdata->txq)
++ ieee80211_init_tx_queue(sdata, NULL, sdata->txq, 0);
++ }
++
+ if (ndev) {
+ if (params) {
+ ndev->ieee80211_ptr->use_4addr = params->use_4addr;
+--- a/net/mac80211/main.c
++++ b/net/mac80211/main.c
+@@ -1004,6 +1004,9 @@ int ieee80211_register_hw(struct ieee802
+
+ local->dynamic_ps_forced_timeout = -1;
+
++ if (!local->hw.txq_ac_max_pending)
++ local->hw.txq_ac_max_pending = 64;
++
+ result = ieee80211_wep_init(local);
+ if (result < 0)
+ wiphy_debug(local->hw.wiphy, "Failed to initialize wep: %d\n",
+--- a/net/mac80211/sta_info.c
++++ b/net/mac80211/sta_info.c
+@@ -119,6 +119,11 @@ static void __cleanup_single_sta(struct
+ sta_info_recalc_tim(sta);
+ }
+
++ if (sta->txq) {
++ for (i = 0; i < IEEE80211_NUM_TIDS; i++)
++ ieee80211_flush_tx_queue(local, sta->sta.txq[i]);
++ }
++
+ for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
+ local->total_ps_buffered -= skb_queue_len(&sta->ps_tx_buf[ac]);
+ ieee80211_purge_tx_queue(&local->hw, &sta->ps_tx_buf[ac]);
+@@ -241,6 +246,8 @@ void sta_info_free(struct ieee80211_loca
+ kfree(sta->tx_lat);
+ }
+
++ kfree(sta->txq);
++
+ sta_dbg(sta->sdata, "Destroyed STA %pM\n", sta->sta.addr);
+
+ kfree(rcu_dereference_raw(sta->sta.rates));
+@@ -294,12 +301,13 @@ struct sta_info *sta_info_alloc(struct i
+ const u8 *addr, gfp_t gfp)
+ {
+ struct ieee80211_local *local = sdata->local;
++ struct ieee80211_hw *hw = &local->hw;
+ struct sta_info *sta;
+ struct timespec uptime;
+ struct ieee80211_tx_latency_bin_ranges *tx_latency;
+ int i;
+
+- sta = kzalloc(sizeof(*sta) + local->hw.sta_data_size, gfp);
++ sta = kzalloc(sizeof(*sta) + hw->sta_data_size, gfp);
+ if (!sta)
+ return NULL;
+
+@@ -357,6 +365,20 @@ struct sta_info *sta_info_alloc(struct i
+ for (i = 0; i < ARRAY_SIZE(sta->chain_signal_avg); i++)
+ ewma_init(&sta->chain_signal_avg[i], 1024, 8);
+
++ if (local->ops->wake_tx_queue) {
++ int size = sizeof(struct txq_info) +
++ ALIGN(hw->txq_data_size, sizeof(void *));
++
++ sta->txq = kcalloc(IEEE80211_NUM_TIDS, size, gfp);
++ if (!sta->txq)
++ goto free;
++
++ for (i = 0; i < IEEE80211_NUM_TIDS; i++) {
++ struct txq_info *txq = sta->txq + i * size;
++ ieee80211_init_tx_queue(sdata, sta, txq, i);
++ }
++ }
++
+ if (sta_prepare_rate_control(local, sta, gfp))
+ goto free;
+
+@@ -380,7 +402,7 @@ struct sta_info *sta_info_alloc(struct i
+ if (sdata->vif.type == NL80211_IFTYPE_AP ||
+ sdata->vif.type == NL80211_IFTYPE_AP_VLAN) {
+ struct ieee80211_supported_band *sband =
+- local->hw.wiphy->bands[ieee80211_get_sdata_band(sdata)];
++ hw->wiphy->bands[ieee80211_get_sdata_band(sdata)];
+ u8 smps = (sband->ht_cap.cap & IEEE80211_HT_CAP_SM_PS) >>
+ IEEE80211_HT_CAP_SM_PS_SHIFT;
+ /*
+--- a/net/mac80211/sta_info.h
++++ b/net/mac80211/sta_info.h
+@@ -371,6 +371,7 @@ struct sta_info {
+ struct sk_buff_head ps_tx_buf[IEEE80211_NUM_ACS];
+ struct sk_buff_head tx_filtered[IEEE80211_NUM_ACS];
+ unsigned long driver_buffered_tids;
++ void *txq;
+
+ /* Updated from RX path only, no locking requirements */
+ unsigned long rx_packets;
+--- a/net/mac80211/trace.h
++++ b/net/mac80211/trace.h
+@@ -2201,6 +2201,40 @@ TRACE_EVENT(drv_get_txpower,
+ )
+ );
+
++DEFINE_EVENT(local_sdata_evt, drv_wake_vif_tx_queue,
++ TP_PROTO(struct ieee80211_local *local,
++ struct ieee80211_sub_if_data *sdata),
++ TP_ARGS(local, sdata)
++);
++
++TRACE_EVENT(drv_wake_sta_tx_queue,
++ TP_PROTO(struct ieee80211_local *local,
++ struct ieee80211_sub_if_data *sdata,
++ struct ieee80211_sta *sta,
++ u8 tid),
++
++ TP_ARGS(local, sdata, sta, tid),
++
++ TP_STRUCT__entry(
++ LOCAL_ENTRY
++ VIF_ENTRY
++ STA_ENTRY
++ __field(u8, tid)
++ ),
++
++ TP_fast_assign(
++ LOCAL_ASSIGN;
++ VIF_ASSIGN;
++ STA_ASSIGN;
++ __entry->tid = tid;
++ ),
++
++ TP_printk(
++ LOCAL_PR_FMT VIF_PR_FMT STA_PR_FMT " tid: 0x%x",
++ LOCAL_PR_ARG, VIF_PR_ARG, STA_PR_ARG, __entry->tid
++ )
++);
++
+
+ #ifdef CPTCFG_MAC80211_MESSAGE_TRACING
+ #undef TRACE_SYSTEM
+--- a/net/mac80211/tx.c
++++ b/net/mac80211/tx.c
+@@ -1198,13 +1198,75 @@ ieee80211_tx_prepare(struct ieee80211_su
+ return TX_CONTINUE;
+ }
+
++static void ieee80211_drv_tx(struct ieee80211_local *local,
++ struct ieee80211_vif *vif,
++ struct ieee80211_sta *pubsta,
++ struct sk_buff *skb)
++{
++ struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
++ struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
++ struct ieee80211_tx_control control = {
++ .sta = pubsta
++ };
++ struct ieee80211_txq *pubtxq = NULL;
++ struct txq_info *txq;
++ u8 ac;
++
++ if (ieee80211_is_mgmt(hdr->frame_control) ||
++ ieee80211_is_ctl(hdr->frame_control))
++ goto tx_normal;
++
++ if (pubsta) {
++ u8 tid = skb->priority & IEEE80211_QOS_CTL_TID_MASK;
++ pubtxq = pubsta->txq[tid];
++ } else {
++ pubtxq = vif->txq;
++ }
++
++ if (!pubtxq)
++ goto tx_normal;
++
++ ac = pubtxq->ac;
++ txq = container_of(pubtxq, struct txq_info, txq);
++ atomic_inc(&sdata->txq_len[ac]);
++ if (atomic_read(&sdata->txq_len[ac]) >= local->hw.txq_ac_max_pending)
++ netif_stop_subqueue(sdata->dev, ac);
++
++ skb_queue_tail(&txq->queue, skb);
++ drv_wake_tx_queue(local, txq);
++
++ return;
++
++tx_normal:
++ drv_tx(local, &control, skb);
++}
++
++int ieee80211_tx_dequeue(struct ieee80211_hw *hw, struct ieee80211_txq *pubtxq,
++ struct sk_buff **dest)
++{
++ struct ieee80211_local *local = hw_to_local(hw);
++ struct ieee80211_sub_if_data *sdata = vif_to_sdata(pubtxq->vif);
++ struct txq_info *txq = container_of(pubtxq, struct txq_info, txq);
++ u8 ac = pubtxq->ac;
++
++ *dest = skb_dequeue(&txq->queue);
++ if (!*dest)
++ return -EAGAIN;
++
++ atomic_dec(&sdata->txq_len[ac]);
++ if (__netif_subqueue_stopped(sdata->dev, ac))
++ ieee80211_propagate_queue_wake(local, sdata->vif.hw_queue[ac]);
++
++ return 0;
++}
++EXPORT_SYMBOL(ieee80211_tx_dequeue);
++
+ static bool ieee80211_tx_frags(struct ieee80211_local *local,
+ struct ieee80211_vif *vif,
+ struct ieee80211_sta *sta,
+ struct sk_buff_head *skbs,
+ bool txpending)
+ {
+- struct ieee80211_tx_control control;
+ struct sk_buff *skb, *tmp;
+ unsigned long flags;
+
+@@ -1262,10 +1324,9 @@ static bool ieee80211_tx_frags(struct ie
+ spin_unlock_irqrestore(&local->queue_stop_reason_lock, flags);
+
+ info->control.vif = vif;
+- control.sta = sta;
+
+ __skb_unlink(skb, skbs);
+- drv_tx(local, &control, skb);
++ ieee80211_drv_tx(local, vif, sta, skb);
+ }
+
+ return true;
+--- a/net/mac80211/util.c
++++ b/net/mac80211/util.c
+@@ -308,6 +308,11 @@ void ieee80211_propagate_queue_wake(stru
+ for (ac = 0; ac < n_acs; ac++) {
+ int ac_queue = sdata->vif.hw_queue[ac];
+
++ if (local->ops->wake_tx_queue &&
++ (atomic_read(&sdata->txq_len[ac]) >
++ local->hw.txq_ac_max_pending))
++ continue;
++
+ if (ac_queue == queue ||
+ (sdata->vif.cab_queue == queue &&
+ local->queue_stop_reasons[ac_queue] == 0 &&
+@@ -3182,3 +3187,33 @@ u8 *ieee80211_add_wmm_info_ie(u8 *buf, u
+
+ return buf;
+ }
++
++void ieee80211_init_tx_queue(struct ieee80211_sub_if_data *sdata,
++ struct sta_info *sta,
++ struct txq_info *txq, int tid)
++{
++ skb_queue_head_init(&txq->queue);
++ txq->txq.vif = &sdata->vif;
++
++ if (sta) {
++ txq->txq.sta = &sta->sta;
++ sta->sta.txq[tid] = &txq->txq;
++ txq->txq.ac = ieee802_1d_to_ac[tid & 7];
++ } else {
++ sdata->vif.txq = &txq->txq;
++ txq->txq.ac = IEEE80211_AC_BE;
++ }
++}
++
++void ieee80211_flush_tx_queue(struct ieee80211_local *local,
++ struct ieee80211_txq *pubtxq)
++{
++ struct txq_info *txq = container_of(pubtxq, struct txq_info, txq);
++ struct ieee80211_sub_if_data *sdata = vif_to_sdata(pubtxq->vif);
++ struct sk_buff *skb;
++
++ while ((skb = skb_dequeue(&txq->queue)) != NULL) {
++ atomic_dec(&sdata->txq_len[pubtxq->ac]);
++ ieee80211_free_txskb(&local->hw, skb);
++ }
++}
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