From: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= Date: Tue, 18 Dec 2018 17:02:06 -0800 Subject: [PATCH] mac80211: Add TXQ scheduling API MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This adds an API to mac80211 to handle scheduling of TXQs. The interface between driver and mac80211 for TXQ handling is changed by adding two new functions: ieee80211_next_txq(), which will return the next TXQ to schedule in the current round-robin rotation, and ieee80211_return_txq(), which the driver uses to indicate that it has finished scheduling a TXQ (which will then be put back in the scheduling rotation if it isn't empty). The driver must call ieee80211_txq_schedule_start() at the start of each scheduling session, and ieee80211_txq_schedule_end() at the end. The API then guarantees that the same TXQ is not returned twice in the same session (so a driver can loop on ieee80211_next_txq() without worrying about breaking the loop. Usage of the new API is optional, so drivers can be ported one at a time. In this patch, the actual scheduling performed by mac80211 is simple round-robin, but a subsequent commit adds airtime fairness awareness to the scheduler. Signed-off-by: Toke Høiland-Jørgensen [minor kernel-doc fix, propagate sparse locking checks out] Signed-off-by: Johannes Berg --- --- a/include/net/mac80211.h +++ b/include/net/mac80211.h @@ -107,9 +107,15 @@ * The driver is expected to initialize its private per-queue data for stations * and interfaces in the .add_interface and .sta_add ops. * - * The driver can't access the queue directly. To dequeue a frame, it calls - * ieee80211_tx_dequeue(). Whenever mac80211 adds a new frame to a queue, it - * calls the .wake_tx_queue driver op. + * The driver can't access the queue directly. To dequeue a frame from a + * txq, it calls ieee80211_tx_dequeue(). Whenever mac80211 adds a new frame to a + * queue, it calls the .wake_tx_queue driver op. + * + * Drivers can optionally delegate responsibility for scheduling queues to + * mac80211, to take advantage of airtime fairness accounting. In this case, to + * obtain the next queue to pull frames from, the driver calls + * ieee80211_next_txq(). The driver is then expected to return the txq using + * ieee80211_return_txq(). * * For AP powersave TIM handling, the driver only needs to indicate if it has * buffered packets in the driver specific data structures by calling @@ -5979,7 +5985,8 @@ void ieee80211_unreserve_tid(struct ieee * ieee80211_tx_dequeue - dequeue a packet from a software tx queue * * @hw: pointer as obtained from ieee80211_alloc_hw() - * @txq: pointer obtained from station or virtual interface + * @txq: pointer obtained from station or virtual interface, or from + * ieee80211_next_txq() * * Returns the skb if successful, %NULL if no frame was available. */ @@ -5987,6 +5994,54 @@ struct sk_buff *ieee80211_tx_dequeue(str struct ieee80211_txq *txq); /** + * ieee80211_next_txq - get next tx queue to pull packets from + * + * @hw: pointer as obtained from ieee80211_alloc_hw() + * @ac: AC number to return packets from. + * + * Should only be called between calls to ieee80211_txq_schedule_start() + * and ieee80211_txq_schedule_end(). + * Returns the next txq if successful, %NULL if no queue is eligible. If a txq + * is returned, it should be returned with ieee80211_return_txq() after the + * driver has finished scheduling it. + */ +struct ieee80211_txq *ieee80211_next_txq(struct ieee80211_hw *hw, u8 ac); + +/** + * ieee80211_return_txq - return a TXQ previously acquired by ieee80211_next_txq() + * + * @hw: pointer as obtained from ieee80211_alloc_hw() + * @txq: pointer obtained from station or virtual interface + * + * Should only be called between calls to ieee80211_txq_schedule_start() + * and ieee80211_txq_schedule_end(). + */ +void ieee80211_return_txq(struct ieee80211_hw *hw, struct ieee80211_txq *txq); + +/** + * ieee80211_txq_schedule_start - acquire locks for safe scheduling of an AC + * + * @hw: pointer as obtained from ieee80211_alloc_hw() + * @ac: AC number to acquire locks for + * + * Acquire locks needed to schedule TXQs from the given AC. Should be called + * before ieee80211_next_txq() or ieee80211_return_txq(). + */ +void ieee80211_txq_schedule_start(struct ieee80211_hw *hw, u8 ac) + __acquires(txq_lock); + +/** + * ieee80211_txq_schedule_end - release locks for safe scheduling of an AC + * + * @hw: pointer as obtained from ieee80211_alloc_hw() + * @ac: AC number to acquire locks for + * + * Release locks previously acquired by ieee80211_txq_schedule_end(). + */ +void ieee80211_txq_schedule_end(struct ieee80211_hw *hw, u8 ac) + __releases(txq_lock); + +/** * ieee80211_txq_get_depth - get pending frame/byte count of given txq * * The values are not guaranteed to be coherent with regard to each other, i.e. --- a/net/mac80211/agg-tx.c +++ b/net/mac80211/agg-tx.c @@ -229,7 +229,7 @@ ieee80211_agg_start_txq(struct sta_info clear_bit(IEEE80211_TXQ_STOP, &txqi->flags); local_bh_disable(); rcu_read_lock(); - drv_wake_tx_queue(sta->sdata->local, txqi); + schedule_and_wake_txq(sta->sdata->local, txqi); rcu_read_unlock(); local_bh_enable(); } --- a/net/mac80211/driver-ops.h +++ b/net/mac80211/driver-ops.h @@ -1176,6 +1176,15 @@ static inline void drv_wake_tx_queue(str local->ops->wake_tx_queue(&local->hw, &txq->txq); } +static inline void schedule_and_wake_txq(struct ieee80211_local *local, + struct txq_info *txqi) +{ + spin_lock_bh(&local->active_txq_lock[txqi->txq.ac]); + ieee80211_return_txq(&local->hw, &txqi->txq); + spin_unlock_bh(&local->active_txq_lock[txqi->txq.ac]); + drv_wake_tx_queue(local, txqi); +} + static inline int drv_start_nan(struct ieee80211_local *local, struct ieee80211_sub_if_data *sdata, struct cfg80211_nan_conf *conf) --- a/net/mac80211/ieee80211_i.h +++ b/net/mac80211/ieee80211_i.h @@ -829,6 +829,8 @@ enum txq_info_flags { * a fq_flow which is already owned by a different tin * @def_cvars: codel vars for @def_flow * @frags: used to keep fragments created after dequeue + * @schedule_order: used with ieee80211_local->active_txqs + * @schedule_round: counter to prevent infinite loops on TXQ scheduling */ struct txq_info { struct fq_tin tin; @@ -836,6 +838,8 @@ struct txq_info { struct codel_vars def_cvars; struct codel_stats cstats; struct sk_buff_head frags; + struct list_head schedule_order; + u16 schedule_round; unsigned long flags; /* keep last! */ @@ -1127,6 +1131,11 @@ struct ieee80211_local { struct codel_vars *cvars; struct codel_params cparams; + /* protects active_txqs and txqi->schedule_order */ + spinlock_t active_txq_lock[IEEE80211_NUM_ACS]; + struct list_head active_txqs[IEEE80211_NUM_ACS]; + u16 schedule_round[IEEE80211_NUM_ACS]; + const struct ieee80211_ops *ops; /* --- a/net/mac80211/main.c +++ b/net/mac80211/main.c @@ -652,6 +652,11 @@ struct ieee80211_hw *ieee80211_alloc_hw_ spin_lock_init(&local->rx_path_lock); spin_lock_init(&local->queue_stop_reason_lock); + for (i = 0; i < IEEE80211_NUM_ACS; i++) { + INIT_LIST_HEAD(&local->active_txqs[i]); + spin_lock_init(&local->active_txq_lock[i]); + } + INIT_LIST_HEAD(&local->chanctx_list); mutex_init(&local->chanctx_mtx); --- a/net/mac80211/sta_info.c +++ b/net/mac80211/sta_info.c @@ -1261,7 +1261,7 @@ void ieee80211_sta_ps_deliver_wakeup(str if (!txq_has_queue(sta->sta.txq[i])) continue; - drv_wake_tx_queue(local, to_txq_info(sta->sta.txq[i])); + schedule_and_wake_txq(local, to_txq_info(sta->sta.txq[i])); } } --- a/net/mac80211/tx.c +++ b/net/mac80211/tx.c @@ -1441,6 +1441,7 @@ void ieee80211_txq_init(struct ieee80211 codel_vars_init(&txqi->def_cvars); codel_stats_init(&txqi->cstats); __skb_queue_head_init(&txqi->frags); + INIT_LIST_HEAD(&txqi->schedule_order); txqi->txq.vif = &sdata->vif; @@ -1464,6 +1465,9 @@ void ieee80211_txq_purge(struct ieee8021 fq_tin_reset(fq, tin, fq_skb_free_func); ieee80211_purge_tx_queue(&local->hw, &txqi->frags); + spin_lock_bh(&local->active_txq_lock[txqi->txq.ac]); + list_del_init(&txqi->schedule_order); + spin_unlock_bh(&local->active_txq_lock[txqi->txq.ac]); } void ieee80211_txq_set_params(struct ieee80211_local *local) @@ -1580,7 +1584,7 @@ static bool ieee80211_queue_skb(struct i ieee80211_txq_enqueue(local, txqi, skb); spin_unlock_bh(&fq->lock); - drv_wake_tx_queue(local, txqi); + schedule_and_wake_txq(local, txqi); return true; } @@ -3631,6 +3635,60 @@ out: } EXPORT_SYMBOL(ieee80211_tx_dequeue); +struct ieee80211_txq *ieee80211_next_txq(struct ieee80211_hw *hw, u8 ac) +{ + struct ieee80211_local *local = hw_to_local(hw); + struct txq_info *txqi = NULL; + + lockdep_assert_held(&local->active_txq_lock[ac]); + + txqi = list_first_entry_or_null(&local->active_txqs[ac], + struct txq_info, + schedule_order); + + if (!txqi || txqi->schedule_round == local->schedule_round[ac]) + return NULL; + + list_del_init(&txqi->schedule_order); + txqi->schedule_round = local->schedule_round[ac]; + return &txqi->txq; +} +EXPORT_SYMBOL(ieee80211_next_txq); + +void ieee80211_return_txq(struct ieee80211_hw *hw, + struct ieee80211_txq *txq) +{ + struct ieee80211_local *local = hw_to_local(hw); + struct txq_info *txqi = to_txq_info(txq); + + lockdep_assert_held(&local->active_txq_lock[txq->ac]); + + if (list_empty(&txqi->schedule_order) && + (!skb_queue_empty(&txqi->frags) || txqi->tin.backlog_packets)) + list_add_tail(&txqi->schedule_order, + &local->active_txqs[txq->ac]); +} +EXPORT_SYMBOL(ieee80211_return_txq); + +void ieee80211_txq_schedule_start(struct ieee80211_hw *hw, u8 ac) + __acquires(txq_lock) +{ + struct ieee80211_local *local = hw_to_local(hw); + + spin_lock_bh(&local->active_txq_lock[ac]); + local->schedule_round[ac]++; +} +EXPORT_SYMBOL(ieee80211_txq_schedule_start); + +void ieee80211_txq_schedule_end(struct ieee80211_hw *hw, u8 ac) + __releases(txq_lock) +{ + struct ieee80211_local *local = hw_to_local(hw); + + spin_unlock_bh(&local->active_txq_lock[ac]); +} +EXPORT_SYMBOL(ieee80211_txq_schedule_end); + void __ieee80211_subif_start_xmit(struct sk_buff *skb, struct net_device *dev, u32 info_flags,