In a loop txqs dequeue scenario, if the first txq in the rbtree gets
removed from rbtree immediately in the ieee80211_return_txq(), the
loop will break soon in the ieee80211_next_txq() due to schedule_pos
not leading to the second txq in the rbtree. Thus, defering the
removal right before the end of this schedule round.
Co-developed-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
Signed-off-by: Yibo Zhao <yiboz@xxxxxxxxxxxxxx>
Signed-off-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
---
include/net/mac80211.h | 16 ++++++++++--
net/mac80211/ieee80211_i.h | 3 +++
net/mac80211/main.c | 6 +++++
net/mac80211/tx.c | 63 +++++++++++++++++++++++++++++++++++++++++++---
4 files changed, 83 insertions(+), 5 deletions(-)
diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index ac2ed8e..ba5a345 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -925,6 +925,8 @@ struct ieee80211_tx_rate {
#define IEEE80211_MAX_TX_RETRY 31
+#define IEEE80211_AIRTIME_TXQ_RM_CHK_INTV_IN_MS 100
+
static inline void ieee80211_rate_set_vht(struct ieee80211_tx_rate *rate,
u8 mcs, u8 nss)
{
@@ -6232,7 +6234,8 @@ struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw,
* @ac: AC number to return packets from.
*
* Should only be called between calls to ieee80211_txq_schedule_start()
- * and ieee80211_txq_schedule_end().
+ * and ieee80211_txq_schedule_end(). If the txq is empty, it will be added
+ * to a remove list and get removed later.
* 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.
@@ -6268,7 +6271,8 @@ void ieee80211_txq_schedule_start(struct ieee80211_hw *hw, u8 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().
+ * Release locks previously acquired by ieee80211_txq_schedule_end(). Check
+ * and remove the empty txq from rb-tree.
*/
void ieee80211_txq_schedule_end(struct ieee80211_hw *hw, u8 ac)
__releases(txq_lock);
@@ -6287,6 +6291,14 @@ void ieee80211_schedule_txq(struct ieee80211_hw *hw, struct ieee80211_txq *txq)
__acquires(txq_lock) __releases(txq_lock);
/**
+ * ieee80211_txqs_check - Check txqs waiting for removal
+ *
+ * @tmr: pointer as obtained from local
+ *
+ */
+void ieee80211_txqs_check(struct timer_list *tmr);
+
+/**
* ieee80211_txq_may_transmit - check whether TXQ is allowed to transmit
*
* This function is used to check whether given txq is allowed to transmit by
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index a4556f9..49aa143e 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -847,6 +847,7 @@ struct txq_info {
struct codel_stats cstats;
struct sk_buff_head frags;
struct rb_node schedule_order;
+ struct list_head candidate;
unsigned long flags;
/* keep last! */
@@ -1145,6 +1146,8 @@ struct ieee80211_local {
u64 airtime_v_t[IEEE80211_NUM_ACS];
u64 airtime_weight_sum[IEEE80211_NUM_ACS];
+ struct list_head remove_list[IEEE80211_NUM_ACS];
+ struct timer_list remove_timer;
u16 airtime_flags;
const struct ieee80211_ops *ops;
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index e9ffa8e..78fe24a 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -667,10 +667,15 @@ struct ieee80211_hw *ieee80211_alloc_hw_nm(size_t priv_data_len,
for (i = 0; i < IEEE80211_NUM_ACS; i++) {
local->active_txqs[i] = RB_ROOT_CACHED;
+ INIT_LIST_HEAD(&local->remove_list[i]);
spin_lock_init(&local->active_txq_lock[i]);
}
local->airtime_flags = AIRTIME_USE_TX | AIRTIME_USE_RX;
+ timer_setup(&local->remove_timer, ieee80211_txqs_check, 0);
+ mod_timer(&local->remove_timer,
+ jiffies + msecs_to_jiffies(IEEE80211_AIRTIME_TXQ_RM_CHK_INTV_IN_MS));
+
INIT_LIST_HEAD(&local->chanctx_list);
mutex_init(&local->chanctx_mtx);
@@ -1305,6 +1310,7 @@ void ieee80211_unregister_hw(struct ieee80211_hw *hw)
tasklet_kill(&local->tx_pending_tasklet);
tasklet_kill(&local->tasklet);
+ del_timer_sync(&local->remove_timer);
#ifdef CONFIG_INET
unregister_inetaddr_notifier(&local->ifa_notifier);
#endif
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index d00baaa..42ca010 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -1450,6 +1450,7 @@ void ieee80211_txq_init(struct ieee80211_sub_if_data *sdata,
codel_stats_init(&txqi->cstats);
__skb_queue_head_init(&txqi->frags);
RB_CLEAR_NODE(&txqi->schedule_order);
+ INIT_LIST_HEAD(&txqi->candidate);
txqi->txq.vif = &sdata->vif;
@@ -3724,6 +3725,9 @@ void ieee80211_schedule_txq(struct ieee80211_hw *hw,
spin_lock_bh(&local->active_txq_lock[ac]);
+ if (!list_empty(&txqi->candidate))
+ list_del_init(&txqi->candidate);
+
if (!RB_EMPTY_NODE(&txqi->schedule_order))
goto out;
@@ -3783,6 +3787,20 @@ static void __ieee80211_unschedule_txq(struct ieee80211_hw *hw,
RB_CLEAR_NODE(&txqi->schedule_order);
}
+void ieee80211_remove_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 (!RB_EMPTY_NODE(&txqi->schedule_order)) {
+ __ieee80211_unschedule_txq(hw, txq);
+ list_del_init(&txqi->candidate);
+ }
+}
+
void ieee80211_unschedule_txq(struct ieee80211_hw *hw,
struct ieee80211_txq *txq)
__acquires(txq_lock) __releases(txq_lock)
@@ -3790,7 +3808,7 @@ void ieee80211_unschedule_txq(struct ieee80211_hw *hw,
struct ieee80211_local *local = hw_to_local(hw);
spin_lock_bh(&local->active_txq_lock[txq->ac]);
- __ieee80211_unschedule_txq(hw, txq);
+ ieee80211_remove_txq(hw, txq);
spin_unlock_bh(&local->active_txq_lock[txq->ac]);
}
@@ -3803,11 +3821,48 @@ void ieee80211_return_txq(struct ieee80211_hw *hw,
lockdep_assert_held(&local->active_txq_lock[txq->ac]);
if (!RB_EMPTY_NODE(&txqi->schedule_order) &&
- (skb_queue_empty(&txqi->frags) && !txqi->tin.backlog_packets))
- __ieee80211_unschedule_txq(hw, txq);
+ !txq_has_queue(&txqi->txq) &&
+ list_empty(&txqi->candidate))
+ list_add_tail(&txqi->candidate, &local->remove_list[txq->ac]);
+
}
EXPORT_SYMBOL(ieee80211_return_txq);
+void __ieee80211_check_txqs(struct ieee80211_local *local, int ac)
+{
+ struct txq_info *iter, *tmp;
+ struct sta_info *sta;
+
+ lockdep_assert_held(&local->active_txq_lock[ac]);
+
+ list_for_each_entry_safe(iter, tmp, &local->remove_list[ac],
+ candidate) {
+ sta = container_of(iter->txq.sta, struct sta_info, sta);
+
+ if (txq_has_queue(&iter->txq))
+ list_del_init(&iter->candidate);
+ else
+ ieee80211_remove_txq(&local->hw, &iter->txq);
+ }
+}
+
+void ieee80211_txqs_check(struct timer_list *t)
+{
+ struct ieee80211_local *local = from_timer(local, t, remove_timer);
+ struct txq_info *iter, *tmp;
+ struct sta_info *sta;
+ int ac;
+
+ for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
+ spin_lock_bh(&local->active_txq_lock[ac]);
+ __ieee80211_check_txqs(local, ac);
+ spin_unlock_bh(&local->active_txq_lock[ac]);
+ }
+
+ mod_timer(&local->remove_timer,
+ jiffies + msecs_to_jiffies(IEEE80211_AIRTIME_TXQ_RM_CHK_INTV_IN_MS));
+}
+
bool ieee80211_txq_may_transmit(struct ieee80211_hw *hw,
struct ieee80211_txq *txq)
{
@@ -3841,6 +3896,8 @@ void ieee80211_txq_schedule_end(struct ieee80211_hw *hw, u8 ac)
struct ieee80211_local *local = hw_to_local(hw);
local->schedule_pos[ac] = NULL;
+ __ieee80211_check_txqs(local, ac);
+
spin_unlock_bh(&local->active_txq_lock[ac]);
}
EXPORT_SYMBOL(ieee80211_txq_schedule_end);
--
1.9.1
