+++ /dev/null
-From: Felix Fietkau <nbd@nbd.name>
-Date: Wed, 13 Mar 2019 19:09:22 +0100
-Subject: [PATCH] mac80211: rework locking for txq scheduling / airtime
- fairness
-
-Holding the lock around the entire duration of tx scheduling can create
-some nasty lock contention, especially when processing airtime information
-from the tx status or the rx path.
-Improve locking by only holding the active_txq_lock for lookups / scheduling
-list modifications.
-
-Signed-off-by: Felix Fietkau <nbd@nbd.name>
----
-
---- a/include/net/mac80211.h
-+++ b/include/net/mac80211.h
-@@ -6069,8 +6069,6 @@ struct sk_buff *ieee80211_tx_dequeue(str
- * @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.
-@@ -6078,51 +6076,41 @@ struct sk_buff *ieee80211_tx_dequeue(str
- 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
-+ * ieee80211_txq_schedule_start - start new scheduling round for TXQs
- *
- * @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().
-+ * 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);
-+void ieee80211_txq_schedule_start(struct ieee80211_hw *hw, u8 ac);
-+
-+/* (deprecated) */
-+static inline void ieee80211_txq_schedule_end(struct ieee80211_hw *hw, u8 ac)
-+{
-+}
-
- /**
-- * ieee80211_txq_schedule_end - release locks for safe scheduling of an AC
-+ * ieee80211_schedule_txq - schedule a TXQ for transmission
- *
- * @hw: pointer as obtained from ieee80211_alloc_hw()
-- * @ac: AC number to acquire locks for
-+ * @txq: pointer obtained from station or virtual interface
- *
-- * Release locks previously acquired by ieee80211_txq_schedule_end().
-+ * Schedules a TXQ for transmission if it is not already scheduled.
- */
--void ieee80211_txq_schedule_end(struct ieee80211_hw *hw, u8 ac)
-- __releases(txq_lock);
-+void ieee80211_schedule_txq(struct ieee80211_hw *hw, struct ieee80211_txq *txq);
-
- /**
-- * ieee80211_schedule_txq - schedule a TXQ for transmission
-+ * 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
-- *
-- * Schedules a TXQ for transmission if it is not already scheduled. Takes a
-- * lock, which means it must *not* be called between
-- * ieee80211_txq_schedule_start() and ieee80211_txq_schedule_end()
- */
--void ieee80211_schedule_txq(struct ieee80211_hw *hw, struct ieee80211_txq *txq)
-- __acquires(txq_lock) __releases(txq_lock);
-+static inline void
-+ieee80211_return_txq(struct ieee80211_hw *hw, struct ieee80211_txq *txq)
-+{
-+ ieee80211_schedule_txq(hw, txq);
-+}
-
- /**
- * ieee80211_txq_may_transmit - check whether TXQ is allowed to transmit
---- a/net/mac80211/tx.c
-+++ b/net/mac80211/tx.c
-@@ -3619,16 +3619,17 @@ 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 ieee80211_txq *ret = NULL;
- struct txq_info *txqi = NULL;
-
-- lockdep_assert_held(&local->active_txq_lock[ac]);
-+ spin_lock_bh(&local->active_txq_lock[ac]);
-
- begin:
- txqi = list_first_entry_or_null(&local->active_txqs[ac],
- struct txq_info,
- schedule_order);
- if (!txqi)
-- return NULL;
-+ goto out;
-
- if (txqi->txq.sta) {
- struct sta_info *sta = container_of(txqi->txq.sta,
-@@ -3645,21 +3646,25 @@ struct ieee80211_txq *ieee80211_next_txq
-
-
- if (txqi->schedule_round == local->schedule_round[ac])
-- return NULL;
-+ goto out;
-
- list_del_init(&txqi->schedule_order);
- txqi->schedule_round = local->schedule_round[ac];
-- return &txqi->txq;
-+ ret = &txqi->txq;
-+
-+out:
-+ spin_unlock_bh(&local->active_txq_lock[ac]);
-+ return ret;
- }
- EXPORT_SYMBOL(ieee80211_next_txq);
-
--void ieee80211_return_txq(struct ieee80211_hw *hw,
-- struct ieee80211_txq *txq)
-+void ieee80211_schedule_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]);
-+ spin_lock_bh(&local->active_txq_lock[txq->ac]);
-
- if (list_empty(&txqi->schedule_order) &&
- (!skb_queue_empty(&txqi->frags) || txqi->tin.backlog_packets)) {
-@@ -3679,18 +3684,7 @@ void ieee80211_return_txq(struct ieee802
- list_add_tail(&txqi->schedule_order,
- &local->active_txqs[txq->ac]);
- }
--}
--EXPORT_SYMBOL(ieee80211_return_txq);
-
--void ieee80211_schedule_txq(struct ieee80211_hw *hw,
-- struct ieee80211_txq *txq)
-- __acquires(txq_lock) __releases(txq_lock)
--{
-- struct ieee80211_local *local = hw_to_local(hw);
-- struct txq_info *txqi = to_txq_info(txq);
--
-- spin_lock_bh(&local->active_txq_lock[txq->ac]);
-- ieee80211_return_txq(hw, txq);
- spin_unlock_bh(&local->active_txq_lock[txq->ac]);
- }
- EXPORT_SYMBOL(ieee80211_schedule_txq);
-@@ -3703,7 +3697,7 @@ bool ieee80211_txq_may_transmit(struct i
- struct sta_info *sta;
- u8 ac = txq->ac;
-
-- lockdep_assert_held(&local->active_txq_lock[ac]);
-+ spin_lock_bh(&local->active_txq_lock[ac]);
-
- if (!txqi->txq.sta)
- goto out;
-@@ -3733,34 +3727,27 @@ bool ieee80211_txq_may_transmit(struct i
-
- sta->airtime[ac].deficit += sta->airtime_weight;
- list_move_tail(&txqi->schedule_order, &local->active_txqs[ac]);
-+ spin_unlock_bh(&local->active_txq_lock[ac]);
-
- return false;
- out:
- if (!list_empty(&txqi->schedule_order))
- list_del_init(&txqi->schedule_order);
-+ spin_unlock_bh(&local->active_txq_lock[ac]);
-
- return true;
- }
- EXPORT_SYMBOL(ieee80211_txq_may_transmit);
-
- 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);
-+EXPORT_SYMBOL(ieee80211_txq_schedule_start);
-
- void __ieee80211_subif_start_xmit(struct sk_buff *skb,
- struct net_device *dev,
projects / openwrt / staging / lynxis.git / blobdiff