package/kernel/mac80211/patches/subsys/320-mac80211-Add-TXQ-scheduling-API.patch

   1 From: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= <toke@toke.dk>
   2 Date: Tue, 18 Dec 2018 17:02:06 -0800
   3 Subject: [PATCH] mac80211: Add TXQ scheduling API
   4 MIME-Version: 1.0
   5 Content-Type: text/plain; charset=UTF-8
   6 Content-Transfer-Encoding: 8bit
   7
   8 This adds an API to mac80211 to handle scheduling of TXQs. The interface
   9 between driver and mac80211 for TXQ handling is changed by adding two new
  10 functions: ieee80211_next_txq(), which will return the next TXQ to schedule
  11 in the current round-robin rotation, and ieee80211_return_txq(), which the
  12 driver uses to indicate that it has finished scheduling a TXQ (which will
  13 then be put back in the scheduling rotation if it isn't empty).
  14
  15 The driver must call ieee80211_txq_schedule_start() at the start of each
  16 scheduling session, and ieee80211_txq_schedule_end() at the end. The API
  17 then guarantees that the same TXQ is not returned twice in the same
  18 session (so a driver can loop on ieee80211_next_txq() without worrying
  19 about breaking the loop.
  20
  21 Usage of the new API is optional, so drivers can be ported one at a time.
  22 In this patch, the actual scheduling performed by mac80211 is simple
  23 round-robin, but a subsequent commit adds airtime fairness awareness to the
  24 scheduler.
  25
  26 Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>
  27 [minor kernel-doc fix, propagate sparse locking checks out]
  28 Signed-off-by: Johannes Berg <johannes.berg@intel.com>
  29 ---
  30
  31 --- a/include/net/mac80211.h
  32 +++ b/include/net/mac80211.h
  33 @@ -107,9 +107,15 @@
  34   * The driver is expected to initialize its private per-queue data for stations
  35   * and interfaces in the .add_interface and .sta_add ops.
  36   *
  37 - * The driver can't access the queue directly. To dequeue a frame, it calls
  38 - * ieee80211_tx_dequeue(). Whenever mac80211 adds a new frame to a queue, it
  39 - * calls the .wake_tx_queue driver op.
  40 + * The driver can't access the queue directly. To dequeue a frame from a
  41 + * txq, it calls ieee80211_tx_dequeue(). Whenever mac80211 adds a new frame to a
  42 + * queue, it calls the .wake_tx_queue driver op.
  43 + *
  44 + * Drivers can optionally delegate responsibility for scheduling queues to
  45 + * mac80211, to take advantage of airtime fairness accounting. In this case, to
  46 + * obtain the next queue to pull frames from, the driver calls
  47 + * ieee80211_next_txq(). The driver is then expected to return the txq using
  48 + * ieee80211_return_txq().
  49   *
  50   * For AP powersave TIM handling, the driver only needs to indicate if it has
  51   * buffered packets in the driver specific data structures by calling
  52 @@ -5979,7 +5985,8 @@ void ieee80211_unreserve_tid(struct ieee
  53   * ieee80211_tx_dequeue - dequeue a packet from a software tx queue
  54   *
  55   * @hw: pointer as obtained from ieee80211_alloc_hw()
  56 - * @txq: pointer obtained from station or virtual interface
  57 + * @txq: pointer obtained from station or virtual interface, or from
  58 + *     ieee80211_next_txq()
  59   *
  60   * Returns the skb if successful, %NULL if no frame was available.
  61   */
  62 @@ -5987,6 +5994,54 @@ struct sk_buff *ieee80211_tx_dequeue(str
  63                                      struct ieee80211_txq *txq);
  64
  65  /**
  66 + * ieee80211_next_txq - get next tx queue to pull packets from
  67 + *
  68 + * @hw: pointer as obtained from ieee80211_alloc_hw()
  69 + * @ac: AC number to return packets from.
  70 + *
  71 + * Should only be called between calls to ieee80211_txq_schedule_start()
  72 + * and ieee80211_txq_schedule_end().
  73 + * Returns the next txq if successful, %NULL if no queue is eligible. If a txq
  74 + * is returned, it should be returned with ieee80211_return_txq() after the
  75 + * driver has finished scheduling it.
  76 + */
  77 +struct ieee80211_txq *ieee80211_next_txq(struct ieee80211_hw *hw, u8 ac);
  78 +
  79 +/**
  80 + * ieee80211_return_txq - return a TXQ previously acquired by ieee80211_next_txq()
  81 + *
  82 + * @hw: pointer as obtained from ieee80211_alloc_hw()
  83 + * @txq: pointer obtained from station or virtual interface
  84 + *
  85 + * Should only be called between calls to ieee80211_txq_schedule_start()
  86 + * and ieee80211_txq_schedule_end().
  87 + */
  88 +void ieee80211_return_txq(struct ieee80211_hw *hw, struct ieee80211_txq *txq);
  89 +
  90 +/**
  91 + * ieee80211_txq_schedule_start - acquire locks for safe scheduling of an AC
  92 + *
  93 + * @hw: pointer as obtained from ieee80211_alloc_hw()
  94 + * @ac: AC number to acquire locks for
  95 + *
  96 + * Acquire locks needed to schedule TXQs from the given AC. Should be called
  97 + * before ieee80211_next_txq() or ieee80211_return_txq().
  98 + */
  99 +void ieee80211_txq_schedule_start(struct ieee80211_hw *hw, u8 ac)
 100 +       __acquires(txq_lock);
 101 +
 102 +/**
 103 + * ieee80211_txq_schedule_end - release locks for safe scheduling of an AC
 104 + *
 105 + * @hw: pointer as obtained from ieee80211_alloc_hw()
 106 + * @ac: AC number to acquire locks for
 107 + *
 108 + * Release locks previously acquired by ieee80211_txq_schedule_end().
 109 + */
 110 +void ieee80211_txq_schedule_end(struct ieee80211_hw *hw, u8 ac)
 111 +       __releases(txq_lock);
 112 +
 113 +/**
 114   * ieee80211_txq_get_depth - get pending frame/byte count of given txq
 115   *
 116   * The values are not guaranteed to be coherent with regard to each other, i.e.
 117 --- a/net/mac80211/agg-tx.c
 118 +++ b/net/mac80211/agg-tx.c
 119 @@ -229,7 +229,7 @@ ieee80211_agg_start_txq(struct sta_info
 120         clear_bit(IEEE80211_TXQ_STOP, &txqi->flags);
 121         local_bh_disable();
 122         rcu_read_lock();
 123 -       drv_wake_tx_queue(sta->sdata->local, txqi);
 124 +       schedule_and_wake_txq(sta->sdata->local, txqi);
 125         rcu_read_unlock();
 126         local_bh_enable();
 127  }
 128 --- a/net/mac80211/driver-ops.h
 129 +++ b/net/mac80211/driver-ops.h
 130 @@ -1176,6 +1176,15 @@ static inline void drv_wake_tx_queue(str
 131         local->ops->wake_tx_queue(&local->hw, &txq->txq);
 132  }
 133
 134 +static inline void schedule_and_wake_txq(struct ieee80211_local *local,
 135 +                                        struct txq_info *txqi)
 136 +{
 137 +       spin_lock_bh(&local->active_txq_lock[txqi->txq.ac]);
 138 +       ieee80211_return_txq(&local->hw, &txqi->txq);
 139 +       spin_unlock_bh(&local->active_txq_lock[txqi->txq.ac]);
 140 +       drv_wake_tx_queue(local, txqi);
 141 +}
 142 +
 143  static inline int drv_start_nan(struct ieee80211_local *local,
 144                                 struct ieee80211_sub_if_data *sdata,
 145                                 struct cfg80211_nan_conf *conf)
 146 --- a/net/mac80211/ieee80211_i.h
 147 +++ b/net/mac80211/ieee80211_i.h
 148 @@ -829,6 +829,8 @@ enum txq_info_flags {
 149   *     a fq_flow which is already owned by a different tin
 150   * @def_cvars: codel vars for @def_flow
 151   * @frags: used to keep fragments created after dequeue
 152 + * @schedule_order: used with ieee80211_local->active_txqs
 153 + * @schedule_round: counter to prevent infinite loops on TXQ scheduling
 154   */
 155  struct txq_info {
 156         struct fq_tin tin;
 157 @@ -836,6 +838,8 @@ struct txq_info {
 158         struct codel_vars def_cvars;
 159         struct codel_stats cstats;
 160         struct sk_buff_head frags;
 161 +       struct list_head schedule_order;
 162 +       u16 schedule_round;
 163         unsigned long flags;
 164
 165         /* keep last! */
 166 @@ -1127,6 +1131,11 @@ struct ieee80211_local {
 167         struct codel_vars *cvars;
 168         struct codel_params cparams;
 169
 170 +       /* protects active_txqs and txqi->schedule_order */
 171 +       spinlock_t active_txq_lock[IEEE80211_NUM_ACS];
 172 +       struct list_head active_txqs[IEEE80211_NUM_ACS];
 173 +       u16 schedule_round[IEEE80211_NUM_ACS];
 174 +
 175         const struct ieee80211_ops *ops;
 176
 177         /*
 178 --- a/net/mac80211/main.c
 179 +++ b/net/mac80211/main.c
 180 @@ -652,6 +652,11 @@ struct ieee80211_hw *ieee80211_alloc_hw_
 181         spin_lock_init(&local->rx_path_lock);
 182         spin_lock_init(&local->queue_stop_reason_lock);
 183
 184 +       for (i = 0; i < IEEE80211_NUM_ACS; i++) {
 185 +               INIT_LIST_HEAD(&local->active_txqs[i]);
 186 +               spin_lock_init(&local->active_txq_lock[i]);
 187 +       }
 188 +
 189         INIT_LIST_HEAD(&local->chanctx_list);
 190         mutex_init(&local->chanctx_mtx);
 191
 192 --- a/net/mac80211/sta_info.c
 193 +++ b/net/mac80211/sta_info.c
 194 @@ -1261,7 +1261,7 @@ void ieee80211_sta_ps_deliver_wakeup(str
 195                         if (!txq_has_queue(sta->sta.txq[i]))
 196                                 continue;
 197
 198 -                       drv_wake_tx_queue(local, to_txq_info(sta->sta.txq[i]));
 199 +                       schedule_and_wake_txq(local, to_txq_info(sta->sta.txq[i]));
 200                 }
 201         }
 202
 203 --- a/net/mac80211/tx.c
 204 +++ b/net/mac80211/tx.c
 205 @@ -1441,6 +1441,7 @@ void ieee80211_txq_init(struct ieee80211
 206         codel_vars_init(&txqi->def_cvars);
 207         codel_stats_init(&txqi->cstats);
 208         __skb_queue_head_init(&txqi->frags);
 209 +       INIT_LIST_HEAD(&txqi->schedule_order);
 210
 211         txqi->txq.vif = &sdata->vif;
 212
 213 @@ -1464,6 +1465,9 @@ void ieee80211_txq_purge(struct ieee8021
 214
 215         fq_tin_reset(fq, tin, fq_skb_free_func);
 216         ieee80211_purge_tx_queue(&local->hw, &txqi->frags);
 217 +       spin_lock_bh(&local->active_txq_lock[txqi->txq.ac]);
 218 +       list_del_init(&txqi->schedule_order);
 219 +       spin_unlock_bh(&local->active_txq_lock[txqi->txq.ac]);
 220  }
 221
 222  void ieee80211_txq_set_params(struct ieee80211_local *local)
 223 @@ -1580,7 +1584,7 @@ static bool ieee80211_queue_skb(struct i
 224         ieee80211_txq_enqueue(local, txqi, skb);
 225         spin_unlock_bh(&fq->lock);
 226
 227 -       drv_wake_tx_queue(local, txqi);
 228 +       schedule_and_wake_txq(local, txqi);
 229
 230         return true;
 231  }
 232 @@ -3631,6 +3635,60 @@ out:
 233  }
 234  EXPORT_SYMBOL(ieee80211_tx_dequeue);
 235
 236 +struct ieee80211_txq *ieee80211_next_txq(struct ieee80211_hw *hw, u8 ac)
 237 +{
 238 +       struct ieee80211_local *local = hw_to_local(hw);
 239 +       struct txq_info *txqi = NULL;
 240 +
 241 +       lockdep_assert_held(&local->active_txq_lock[ac]);
 242 +
 243 +       txqi = list_first_entry_or_null(&local->active_txqs[ac],
 244 +                                       struct txq_info,
 245 +                                       schedule_order);
 246 +
 247 +       if (!txqi || txqi->schedule_round == local->schedule_round[ac])
 248 +               return NULL;
 249 +
 250 +       list_del_init(&txqi->schedule_order);
 251 +       txqi->schedule_round = local->schedule_round[ac];
 252 +       return &txqi->txq;
 253 +}
 254 +EXPORT_SYMBOL(ieee80211_next_txq);
 255 +
 256 +void ieee80211_return_txq(struct ieee80211_hw *hw,
 257 +                         struct ieee80211_txq *txq)
 258 +{
 259 +       struct ieee80211_local *local = hw_to_local(hw);
 260 +       struct txq_info *txqi = to_txq_info(txq);
 261 +
 262 +       lockdep_assert_held(&local->active_txq_lock[txq->ac]);
 263 +
 264 +       if (list_empty(&txqi->schedule_order) &&
 265 +           (!skb_queue_empty(&txqi->frags) || txqi->tin.backlog_packets))
 266 +               list_add_tail(&txqi->schedule_order,
 267 +                             &local->active_txqs[txq->ac]);
 268 +}
 269 +EXPORT_SYMBOL(ieee80211_return_txq);
 270 +
 271 +void ieee80211_txq_schedule_start(struct ieee80211_hw *hw, u8 ac)
 272 +       __acquires(txq_lock)
 273 +{
 274 +       struct ieee80211_local *local = hw_to_local(hw);
 275 +
 276 +       spin_lock_bh(&local->active_txq_lock[ac]);
 277 +       local->schedule_round[ac]++;
 278 +}
 279 +EXPORT_SYMBOL(ieee80211_txq_schedule_start);
 280 +
 281 +void ieee80211_txq_schedule_end(struct ieee80211_hw *hw, u8 ac)
 282 +       __releases(txq_lock)
 283 +{
 284 +       struct ieee80211_local *local = hw_to_local(hw);
 285 +
 286 +       spin_unlock_bh(&local->active_txq_lock[ac]);
 287 +}
 288 +EXPORT_SYMBOL(ieee80211_txq_schedule_end);
 289 +
 290  void __ieee80211_subif_start_xmit(struct sk_buff *skb,
 291                                   struct net_device *dev,
 292                                   u32 info_flags,