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>

6 files changed, 159 insertions, 3 deletions

diff --git a/drivers/net/wireless/ath/ath9k/htc.h b/drivers/net/wireless/ath/ath9k/htc.h
index b40753ca6706..b413b46119b0 100644
--- a/drivers/net/wireless/ath/ath9k/htc.h
+++ b/drivers/net/wireless/ath/ath9k/htc.h
@@ -262,7 +262,10 @@ struct ath9k_htc_rx {
         spinlock_t rxbuflock;
 };
 
-#define ATH9K_HTC_TX_RESERVE   10
+#define ATH9K_HTC_TX_CLEANUP_INTERVAL 50 /* ms */
+#define ATH9K_HTC_TX_TIMEOUT_INTERVAL 2500 /* ms */
+#define ATH9K_HTC_TX_RESERVE 10
+#define ATH9K_HTC_TX_TIMEOUT_COUNT 20
 #define ATH9K_HTC_TX_THRESHOLD (MAX_TX_BUF_NUM - ATH9K_HTC_TX_RESERVE)
 
 #define ATH9K_HTC_OP_TX_QUEUES_STOP BIT(0)
@@ -279,6 +282,7 @@ struct ath9k_htc_tx {
         struct sk_buff_head data_vo_queue;
         struct sk_buff_head tx_failed;
         DECLARE_BITMAP(tx_slot, MAX_TX_BUF_NUM);
+        struct timer_list cleanup_timer;
         spinlock_t tx_lock;
 };
 
@@ -287,6 +291,7 @@ struct ath9k_htc_tx_ctl {
         u8 epid;
         u8 txok;
         u8 sta_idx;
+        unsigned long timestamp;
 };
 
 static inline struct ath9k_htc_tx_ctl *HTC_SKB_CB(struct sk_buff *skb)
@@ -557,6 +562,7 @@ void ath9k_htc_tx_drain(struct ath9k_htc_priv *priv);
 void ath9k_htc_txstatus(struct ath9k_htc_priv *priv, void *wmi_event);
 void ath9k_htc_tx_failed(struct ath9k_htc_priv *priv);
 void ath9k_tx_failed_tasklet(unsigned long data);
+void ath9k_htc_tx_cleanup_timer(unsigned long data);
 
 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_init.c b/drivers/net/wireless/ath/ath9k/htc_drv_init.c
index afceeaa6b916..0aec25920c0a 100644
--- a/drivers/net/wireless/ath/ath9k/htc_drv_init.c
+++ b/drivers/net/wireless/ath/ath9k/htc_drv_init.c
@@ -671,7 +671,6 @@ static int ath9k_init_priv(struct ath9k_htc_priv *priv,
         common->priv = priv;
         common->debug_mask = ath9k_debug;
 
-        spin_lock_init(&priv->wmi->wmi_lock);
         spin_lock_init(&priv->beacon_lock);
         spin_lock_init(&priv->tx.tx_lock);
         mutex_init(&priv->mutex);
@@ -683,6 +682,8 @@ static int ath9k_init_priv(struct ath9k_htc_priv *priv,
         INIT_DELAYED_WORK(&priv->ani_work, ath9k_htc_ani_work);
         INIT_WORK(&priv->ps_work, ath9k_ps_work);
         INIT_WORK(&priv->fatal_work, ath9k_fatal_work);
+        setup_timer(&priv->tx.cleanup_timer, ath9k_htc_tx_cleanup_timer,
+                    (unsigned long)priv);
 
         /*
          * Cache line size is used to size and align various
diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_main.c b/drivers/net/wireless/ath/ath9k/htc_drv_main.c
index ae85cc4373f0..4de38643cb53 100644
--- a/drivers/net/wireless/ath/ath9k/htc_drv_main.c
+++ b/drivers/net/wireless/ath/ath9k/htc_drv_main.c
@@ -194,6 +194,7 @@ void ath9k_htc_reset(struct ath9k_htc_priv *priv)
         ath9k_htc_stop_ani(priv);
         ieee80211_stop_queues(priv->hw);
 
+        del_timer_sync(&priv->tx.cleanup_timer);
         ath9k_htc_tx_drain(priv);
 
         WMI_CMD(WMI_DISABLE_INTR_CMDID);
@@ -225,6 +226,9 @@ void ath9k_htc_reset(struct ath9k_htc_priv *priv)
         ath9k_htc_vif_reconfig(priv);
         ieee80211_wake_queues(priv->hw);
 
+        mod_timer(&priv->tx.cleanup_timer,
+                  jiffies + msecs_to_jiffies(ATH9K_HTC_TX_CLEANUP_INTERVAL));
+
         ath9k_htc_ps_restore(priv);
         mutex_unlock(&priv->mutex);
 }
@@ -251,6 +255,7 @@ static int ath9k_htc_set_channel(struct ath9k_htc_priv *priv,
 
         ath9k_htc_ps_wakeup(priv);
 
+        del_timer_sync(&priv->tx.cleanup_timer);
         ath9k_htc_tx_drain(priv);
 
         WMI_CMD(WMI_DISABLE_INTR_CMDID);
@@ -301,6 +306,9 @@ static int ath9k_htc_set_channel(struct ath9k_htc_priv *priv,
             !(hw->conf.flags & IEEE80211_CONF_OFFCHANNEL))
                 ath9k_htc_vif_reconfig(priv);
 
+        mod_timer(&priv->tx.cleanup_timer,
+                  jiffies + msecs_to_jiffies(ATH9K_HTC_TX_CLEANUP_INTERVAL));
+
 err:
         ath9k_htc_ps_restore(priv);
         return ret;
@@ -937,6 +945,9 @@ static int ath9k_htc_start(struct ieee80211_hw *hw)
 
         ieee80211_wake_queues(hw);
 
+        mod_timer(&priv->tx.cleanup_timer,
+                  jiffies + msecs_to_jiffies(ATH9K_HTC_TX_CLEANUP_INTERVAL));
+
         if (ah->btcoex_hw.scheme == ATH_BTCOEX_CFG_3WIRE) {
                 ath9k_hw_btcoex_set_weight(ah, AR_BT_COEX_WGHT,
                                            AR_STOMP_LOW_WLAN_WGHT);
@@ -972,6 +983,7 @@ static void ath9k_htc_stop(struct ieee80211_hw *hw)
 
         tasklet_kill(&priv->rx_tasklet);
 
+        del_timer_sync(&priv->tx.cleanup_timer);
         ath9k_htc_tx_drain(priv);
         ath9k_wmi_event_drain(priv);
 
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);
diff --git a/drivers/net/wireless/ath/ath9k/wmi.c b/drivers/net/wireless/ath/ath9k/wmi.c
index 3f5a4d1fe077..697e5af842c1 100644
--- a/drivers/net/wireless/ath/ath9k/wmi.c
+++ b/drivers/net/wireless/ath/ath9k/wmi.c
@@ -91,9 +91,12 @@ struct wmi *ath9k_init_wmi(struct ath9k_htc_priv *priv)
         wmi->drv_priv = priv;
         wmi->stopped = false;
         skb_queue_head_init(&wmi->wmi_event_queue);
+        spin_lock_init(&wmi->wmi_lock);
+        spin_lock_init(&wmi->event_lock);
         mutex_init(&wmi->op_mutex);
         mutex_init(&wmi->multi_write_mutex);
         init_completion(&wmi->cmd_wait);
+        INIT_LIST_HEAD(&wmi->pending_tx_events);
         tasklet_init(&wmi->wmi_event_tasklet, ath9k_wmi_event_tasklet,
                      (unsigned long)wmi);
 
diff --git a/drivers/net/wireless/ath/ath9k/wmi.h b/drivers/net/wireless/ath/ath9k/wmi.h
index 44b17385374f..310d94eaed19 100644
--- a/drivers/net/wireless/ath/ath9k/wmi.h
+++ b/drivers/net/wireless/ath/ath9k/wmi.h
@@ -130,6 +130,12 @@ struct register_write {
         __be32 val;
 };
 
+struct ath9k_htc_tx_event {
+        int count;
+        struct __wmi_event_txstatus txs;
+        struct list_head list;
+};
+
 struct wmi {
         struct ath9k_htc_priv *drv_priv;
         struct htc_target *htc;
@@ -144,6 +150,9 @@ struct wmi {
         u32 cmd_rsp_len;
         bool stopped;
 
+        struct list_head pending_tx_events;
+        spinlock_t event_lock;
+
         spinlock_t wmi_lock;
 
         atomic_t mwrite_cnt;