ath9k_htc: Fix TX queue management

Handle queue start/stop properly by maintaining
a counter to check if the pending frame count has
exceeded the threshold. Otherwise, packets would be
dropped needlessly. While at it, use a simple flag
to track queue status and use helper functions too.

Signed-off-by: Sujith Manoharan <Sujith.Manoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

5 files changed, 52 insertions, 27 deletions

diff --git a/drivers/net/wireless/ath/ath9k/htc.h b/drivers/net/wireless/ath/ath9k/htc.h
index 3185fe7568c..fc4c466e756 100644
--- a/drivers/net/wireless/ath/ath9k/htc.h
+++ b/drivers/net/wireless/ath/ath9k/htc.h
@@ -262,11 +262,16 @@ struct ath9k_htc_rx {
         spinlock_t rxbuflock;
 };
 
-struct ath9k_htc_tx {
-        bool tx_queues_stop;
-        spinlock_t tx_lock;
+#define ATH9K_HTC_TX_RESERVE   10
+#define ATH9K_HTC_TX_THRESHOLD (MAX_TX_BUF_NUM - ATH9K_HTC_TX_RESERVE)
+
+#define ATH9K_HTC_OP_TX_QUEUES_STOP BIT(0)
 
+struct ath9k_htc_tx {
+        u8 flags;
+        int queued_cnt;
         struct sk_buff_head tx_queue;
+        spinlock_t tx_lock;
 };
 
 struct ath9k_htc_tx_ctl {
@@ -532,6 +537,8 @@ int ath9k_htc_cabq_setup(struct ath9k_htc_priv *priv);
 int get_hw_qnum(u16 queue, int *hwq_map);
 int ath_htc_txq_update(struct ath9k_htc_priv *priv, int qnum,
                        struct ath9k_tx_queue_info *qinfo);
+void ath9k_htc_check_stop_queues(struct ath9k_htc_priv *priv);
+void ath9k_htc_check_wake_queues(struct ath9k_htc_priv *priv);
 
 int ath9k_rx_init(struct ath9k_htc_priv *priv);
 void ath9k_rx_cleanup(struct ath9k_htc_priv *priv);
diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_beacon.c b/drivers/net/wireless/ath/ath9k/htc_drv_beacon.c
index 713def18451..de37d46bb0d 100644
--- a/drivers/net/wireless/ath/ath9k/htc_drv_beacon.c
+++ b/drivers/net/wireless/ath/ath9k/htc_drv_beacon.c
@@ -326,6 +326,10 @@ static void ath9k_htc_send_buffered(struct ath9k_htc_priv *priv,
                         ath_dbg(common, ATH_DBG_FATAL,
                                 "Failed to send CAB frame\n");
                         dev_kfree_skb_any(skb);
+                } else {
+                        spin_lock_bh(&priv->tx.tx_lock);
+                        priv->tx.queued_cnt++;
+                        spin_unlock_bh(&priv->tx.tx_lock);
                 }
         next:
                 skb = ieee80211_get_buffered_bc(priv->hw, vif);
diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_gpio.c b/drivers/net/wireless/ath/ath9k/htc_drv_gpio.c
index 1f6df4a1d22..92e4b312a98 100644
--- a/drivers/net/wireless/ath/ath9k/htc_drv_gpio.c
+++ b/drivers/net/wireless/ath/ath9k/htc_drv_gpio.c
@@ -399,7 +399,7 @@ void ath9k_htc_radio_enable(struct ieee80211_hw *hw)
         /* Start TX */
         htc_start(priv->htc);
         spin_lock_bh(&priv->tx.tx_lock);
-        priv->tx.tx_queues_stop = false;
+        priv->tx.flags &= ~ATH9K_HTC_OP_TX_QUEUES_STOP;
         spin_unlock_bh(&priv->tx.tx_lock);
         ieee80211_wake_queues(hw);
 
diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_main.c b/drivers/net/wireless/ath/ath9k/htc_drv_main.c
index ff3a49577a0..690113673d2 100644
--- a/drivers/net/wireless/ath/ath9k/htc_drv_main.c
+++ b/drivers/net/wireless/ath/ath9k/htc_drv_main.c
@@ -833,6 +833,7 @@ static void ath9k_htc_tx(struct ieee80211_hw *hw, struct sk_buff *skb)
 {
         struct ieee80211_hdr *hdr;
         struct ath9k_htc_priv *priv = hw->priv;
+        struct ath_common *common = ath9k_hw_common(priv->ah);
         int padpos, padsize, ret;
 
         hdr = (struct ieee80211_hdr *) skb->data;
@@ -841,28 +842,22 @@ static void ath9k_htc_tx(struct ieee80211_hw *hw, struct sk_buff *skb)
         padpos = ath9k_cmn_padpos(hdr->frame_control);
         padsize = padpos & 3;
         if (padsize && skb->len > padpos) {
-                if (skb_headroom(skb) < padsize)
+                if (skb_headroom(skb) < padsize) {
+                        ath_dbg(common, ATH_DBG_XMIT, "No room for padding\n");
                         goto fail_tx;
+                }
                 skb_push(skb, padsize);
                 memmove(skb->data, skb->data + padsize, padpos);
         }
 
         ret = ath9k_htc_tx_start(priv, skb, false);
         if (ret != 0) {
-                if (ret == -ENOMEM) {
-                        ath_dbg(ath9k_hw_common(priv->ah), ATH_DBG_XMIT,
-                                "Stopping TX queues\n");
-                        ieee80211_stop_queues(hw);
-                        spin_lock_bh(&priv->tx.tx_lock);
-                        priv->tx.tx_queues_stop = true;
-                        spin_unlock_bh(&priv->tx.tx_lock);
-                } else {
-                        ath_dbg(ath9k_hw_common(priv->ah), ATH_DBG_XMIT,
-                                "Tx failed\n");
-                }
+                ath_dbg(common, ATH_DBG_XMIT, "Tx failed\n");
                 goto fail_tx;
         }
 
+        ath9k_htc_check_stop_queues(priv);
+
         return;
 
 fail_tx:
@@ -924,7 +919,7 @@ static int ath9k_htc_start(struct ieee80211_hw *hw)
         htc_start(priv->htc);
 
         spin_lock_bh(&priv->tx.tx_lock);
-        priv->tx.tx_queues_stop = false;
+        priv->tx.flags &= ~ATH9K_HTC_OP_TX_QUEUES_STOP;
         spin_unlock_bh(&priv->tx.tx_lock);
 
         ieee80211_wake_queues(hw);
diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_txrx.c b/drivers/net/wireless/ath/ath9k/htc_drv_txrx.c
index 6f7987d7b6b..1cbe194179a 100644
--- a/drivers/net/wireless/ath/ath9k/htc_drv_txrx.c
+++ b/drivers/net/wireless/ath/ath9k/htc_drv_txrx.c
@@ -53,6 +53,29 @@ int get_hw_qnum(u16 queue, int *hwq_map)
         }
 }
 
+void ath9k_htc_check_stop_queues(struct ath9k_htc_priv *priv)
+{
+        spin_lock_bh(&priv->tx.tx_lock);
+        priv->tx.queued_cnt++;
+        if ((priv->tx.queued_cnt >= ATH9K_HTC_TX_THRESHOLD) &&
+            !(priv->tx.flags & ATH9K_HTC_OP_TX_QUEUES_STOP)) {
+                priv->tx.flags |= ATH9K_HTC_OP_TX_QUEUES_STOP;
+                ieee80211_stop_queues(priv->hw);
+        }
+        spin_unlock_bh(&priv->tx.tx_lock);
+}
+
+void ath9k_htc_check_wake_queues(struct ath9k_htc_priv *priv)
+{
+        spin_lock_bh(&priv->tx.tx_lock);
+        if ((priv->tx.queued_cnt < ATH9K_HTC_TX_THRESHOLD) &&
+            (priv->tx.flags & ATH9K_HTC_OP_TX_QUEUES_STOP)) {
+                priv->tx.flags &= ~ATH9K_HTC_OP_TX_QUEUES_STOP;
+                ieee80211_wake_queues(priv->hw);
+        }
+        spin_unlock_bh(&priv->tx.tx_lock);
+}
+
 int ath_htc_txq_update(struct ath9k_htc_priv *priv, int qnum,
                        struct ath9k_tx_queue_info *qinfo)
 {
@@ -302,21 +325,17 @@ void ath9k_tx_tasklet(unsigned long data)
                 rcu_read_unlock();
 
         send_mac80211:
+                spin_lock_bh(&priv->tx.tx_lock);
+                if (WARN_ON(--priv->tx.queued_cnt < 0))
+                        priv->tx.queued_cnt = 0;
+                spin_unlock_bh(&priv->tx.tx_lock);
+
                 /* Send status to mac80211 */
                 ieee80211_tx_status(priv->hw, skb);
         }
 
         /* Wake TX queues if needed */
-        spin_lock_bh(&priv->tx.tx_lock);
-        if (priv->tx.tx_queues_stop) {
-                priv->tx.tx_queues_stop = false;
-                spin_unlock_bh(&priv->tx.tx_lock);
-                ath_dbg(ath9k_hw_common(priv->ah), ATH_DBG_XMIT,
-                        "Waking up TX queues\n");
-                ieee80211_wake_queues(priv->hw);
-                return;
-        }
-        spin_unlock_bh(&priv->tx.tx_lock);
+        ath9k_htc_check_wake_queues(priv);
 }
 
 void ath9k_htc_txep(void *drv_priv, struct sk_buff *skb,