ath9k_htc: Add a timer to cleanup WMI events

Occasionally, a WMI event would arrive ahead of the TX
URB completion handler. Discarding these events would exhaust
the available TX slots, so handle them by running a timer
cleaning up such events. Also, timeout packets for which TX
completion events have not arrived.

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

1 files changed, 126 insertions, 1 deletions

diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_txrx.c b/drivers/net/wireless/ath/ath9k/htc_drv_txrx.c
index a9b6bb1ef287..86f5ce9b6e0e 100644
--- a/drivers/net/wireless/ath/ath9k/htc_drv_txrx.c
+++ b/drivers/net/wireless/ath/ath9k/htc_drv_txrx.c
@@ -495,6 +495,8 @@ static inline void ath9k_htc_tx_drainq(struct ath9k_htc_priv *priv,
 
 void ath9k_htc_tx_drain(struct ath9k_htc_priv *priv)
 {
+        struct ath9k_htc_tx_event *event, *tmp;
+
         spin_lock_bh(&priv->tx.tx_lock);
         priv->tx.flags |= ATH9K_HTC_OP_TX_DRAIN;
         spin_unlock_bh(&priv->tx.tx_lock);
@@ -515,6 +517,16 @@ void ath9k_htc_tx_drain(struct ath9k_htc_priv *priv)
         ath9k_htc_tx_drainq(priv, &priv->tx.data_vo_queue);
         ath9k_htc_tx_drainq(priv, &priv->tx.tx_failed);
 
+        /*
+         * The TX cleanup timer has already been killed.
+         */
+        spin_lock_bh(&priv->wmi->event_lock);
+        list_for_each_entry_safe(event, tmp, &priv->wmi->pending_tx_events, list) {
+                list_del(&event->list);
+                kfree(event);
+        }
+        spin_unlock_bh(&priv->wmi->event_lock);
+
         spin_lock_bh(&priv->tx.tx_lock);
         priv->tx.flags &= ~ATH9K_HTC_OP_TX_DRAIN;
         spin_unlock_bh(&priv->tx.tx_lock);
@@ -595,6 +607,7 @@ void ath9k_htc_txstatus(struct ath9k_htc_priv *priv, void *wmi_event)
         struct wmi_event_txstatus *txs = (struct wmi_event_txstatus *)wmi_event;
         struct __wmi_event_txstatus *__txs;
         struct sk_buff *skb;
+        struct ath9k_htc_tx_event *tx_pend;
         int i;
 
         for (i = 0; i < txs->cnt; i++) {
@@ -603,8 +616,26 @@ void ath9k_htc_txstatus(struct ath9k_htc_priv *priv, void *wmi_event)
                 __txs = &txs->txstatus[i];
 
                 skb = ath9k_htc_tx_get_packet(priv, __txs);
-                if (!skb)
+                if (!skb) {
+                        /*
+                         * Store this event, so that the TX cleanup
+                         * routine can check later for the needed packet.
+                         */
+                        tx_pend = kzalloc(sizeof(struct ath9k_htc_tx_event),
+                                          GFP_ATOMIC);
+                        if (!tx_pend)
+                                continue;
+
+                        memcpy(&tx_pend->txs, __txs,
+                               sizeof(struct __wmi_event_txstatus));
+
+                        spin_lock(&priv->wmi->event_lock);
+                        list_add_tail(&tx_pend->list,
+                                      &priv->wmi->pending_tx_events);
+                        spin_unlock(&priv->wmi->event_lock);
+
                         continue;
+                }
 
                 ath9k_htc_tx_process(priv, skb, __txs);
         }
@@ -622,6 +653,7 @@ void ath9k_htc_txep(void *drv_priv, struct sk_buff *skb,
 
         tx_ctl = HTC_SKB_CB(skb);
         tx_ctl->txok = txok;
+        tx_ctl->timestamp = jiffies;
 
         if (!txok) {
                 skb_queue_tail(&priv->tx.tx_failed, skb);
@@ -638,6 +670,99 @@ void ath9k_htc_txep(void *drv_priv, struct sk_buff *skb,
         skb_queue_tail(epid_queue, skb);
 }
 
+static inline bool check_packet(struct ath9k_htc_priv *priv, struct sk_buff *skb)
+{
+        struct ath_common *common = ath9k_hw_common(priv->ah);
+        struct ath9k_htc_tx_ctl *tx_ctl;
+
+        tx_ctl = HTC_SKB_CB(skb);
+
+        if (time_after(jiffies,
+                       tx_ctl->timestamp +
+                       msecs_to_jiffies(ATH9K_HTC_TX_TIMEOUT_INTERVAL))) {
+                ath_dbg(common, ATH_DBG_XMIT,
+                        "Dropping a packet due to TX timeout\n");
+                return true;
+        }
+
+        return false;
+}
+
+static void ath9k_htc_tx_cleanup_queue(struct ath9k_htc_priv *priv,
+                                       struct sk_buff_head *epid_queue)
+{
+        bool process = false;
+        unsigned long flags;
+        struct sk_buff *skb, *tmp;
+        struct sk_buff_head queue;
+
+        skb_queue_head_init(&queue);
+
+        spin_lock_irqsave(&epid_queue->lock, flags);
+        skb_queue_walk_safe(epid_queue, skb, tmp) {
+                if (check_packet(priv, skb)) {
+                        __skb_unlink(skb, epid_queue);
+                        __skb_queue_tail(&queue, skb);
+                        process = true;
+                }
+        }
+        spin_unlock_irqrestore(&epid_queue->lock, flags);
+
+        if (process) {
+                skb_queue_walk_safe(&queue, skb, tmp) {
+                        __skb_unlink(skb, &queue);
+                        ath9k_htc_tx_process(priv, skb, NULL);
+                }
+        }
+}
+
+void ath9k_htc_tx_cleanup_timer(unsigned long data)
+{
+        struct ath9k_htc_priv *priv = (struct ath9k_htc_priv *) data;
+        struct ath_common *common = ath9k_hw_common(priv->ah);
+        struct ath9k_htc_tx_event *event, *tmp;
+        struct sk_buff *skb;
+
+        spin_lock(&priv->wmi->event_lock);
+        list_for_each_entry_safe(event, tmp, &priv->wmi->pending_tx_events, list) {
+
+                skb = ath9k_htc_tx_get_packet(priv, &event->txs);
+                if (skb) {
+                        ath_dbg(common, ATH_DBG_XMIT,
+                                "Found packet for cookie: %d, epid: %d\n",
+                                event->txs.cookie,
+                                MS(event->txs.ts_rate, ATH9K_HTC_TXSTAT_EPID));
+
+                        ath9k_htc_tx_process(priv, skb, &event->txs);
+                        list_del(&event->list);
+                        kfree(event);
+                        continue;
+                }
+
+                if (++event->count >= ATH9K_HTC_TX_TIMEOUT_COUNT) {
+                        list_del(&event->list);
+                        kfree(event);
+                }
+        }
+        spin_unlock(&priv->wmi->event_lock);
+
+        /*
+         * Check if status-pending packets have to be cleaned up.
+         */
+        ath9k_htc_tx_cleanup_queue(priv, &priv->tx.mgmt_ep_queue);
+        ath9k_htc_tx_cleanup_queue(priv, &priv->tx.cab_ep_queue);
+        ath9k_htc_tx_cleanup_queue(priv, &priv->tx.data_be_queue);
+        ath9k_htc_tx_cleanup_queue(priv, &priv->tx.data_bk_queue);
+        ath9k_htc_tx_cleanup_queue(priv, &priv->tx.data_vi_queue);
+        ath9k_htc_tx_cleanup_queue(priv, &priv->tx.data_vo_queue);
+
+        /* Wake TX queues if needed */
+        ath9k_htc_check_wake_queues(priv);
+
+        mod_timer(&priv->tx.cleanup_timer,
+                  jiffies + msecs_to_jiffies(ATH9K_HTC_TX_CLEANUP_INTERVAL));
+}
+
 int ath9k_tx_init(struct ath9k_htc_priv *priv)
 {
         skb_queue_head_init(&priv->tx.mgmt_ep_queue);