ath9k_htc: Drain pending TX frames properly

When doing a channel set or a reset operation the pending
frames queued up for transmission have to be flushed and
sent to mac80211. Fixing this has to be done in two separate
steps:

  * Flush queued frames and kill the URB TX completion handler.
  * Complete all the frames that in the TX pending queue.

This patch adds proper support for draining and all the callsites
namely, channel change/reset/idle/stop are fixed. A separate queue
is used for handling failed frames.

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

6 files changed, 69 insertions, 49 deletions

diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
index 0b63a48462c..db07e7b9320 100644
--- a/drivers/net/wireless/ath/ath9k/hif_usb.c
+++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
@@ -131,7 +131,19 @@ static inline void ath9k_skb_queue_purge(struct hif_device_usb *hif_dev,
 
         while ((skb = __skb_dequeue(list)) != NULL) {
                 dev_kfree_skb_any(skb);
-                TX_STAT_INC(skb_dropped);
+        }
+}
+
+static inline void ath9k_skb_queue_complete(struct hif_device_usb *hif_dev,
+                                            struct sk_buff_head *queue,
+                                            bool txok)
+{
+        struct sk_buff *skb;
+
+        while ((skb = __skb_dequeue(queue)) != NULL) {
+                ath9k_htc_txcompletion_cb(hif_dev->htc_handle,
+                                          skb, txok);
+                (txok) ? TX_STAT_INC(skb_success) : TX_STAT_INC(skb_failed);
         }
 }
 
@@ -139,7 +151,7 @@ static void hif_usb_tx_cb(struct urb *urb)
 {
         struct tx_buf *tx_buf = (struct tx_buf *) urb->context;
         struct hif_device_usb *hif_dev;
-        struct sk_buff *skb;
+        bool txok = true;
 
         if (!tx_buf || !tx_buf->hif_dev)
                 return;
@@ -153,10 +165,7 @@ static void hif_usb_tx_cb(struct urb *urb)
         case -ECONNRESET:
         case -ENODEV:
         case -ESHUTDOWN:
-                /*
-                 * The URB has been killed, free the SKBs.
-                 */
-                ath9k_skb_queue_purge(hif_dev, &tx_buf->skb_queue);
+                txok = false;
 
                 /*
                  * If the URBs are being flushed, no need to add this
@@ -165,41 +174,19 @@ static void hif_usb_tx_cb(struct urb *urb)
                 spin_lock(&hif_dev->tx.tx_lock);
                 if (hif_dev->tx.flags & HIF_USB_TX_FLUSH) {
                         spin_unlock(&hif_dev->tx.tx_lock);
+                        ath9k_skb_queue_purge(hif_dev, &tx_buf->skb_queue);
                         return;
                 }
                 spin_unlock(&hif_dev->tx.tx_lock);
 
-                /*
-                 * In the stop() case, this URB has to be added to
-                 * the free list.
-                 */
-                goto add_free;
+                break;
         default:
+                txok = false;
                 break;
         }
 
-        /*
-         * Check if TX has been stopped, this is needed because
-         * this CB could have been invoked just after the TX lock
-         * was released in hif_stop() and kill_urb() hasn't been
-         * called yet.
-         */
-        spin_lock(&hif_dev->tx.tx_lock);
-        if (hif_dev->tx.flags & HIF_USB_TX_STOP) {
-                spin_unlock(&hif_dev->tx.tx_lock);
-                ath9k_skb_queue_purge(hif_dev, &tx_buf->skb_queue);
-                goto add_free;
-        }
-        spin_unlock(&hif_dev->tx.tx_lock);
-
-        /* Complete the queued SKBs. */
-        while ((skb = __skb_dequeue(&tx_buf->skb_queue)) != NULL) {
-                ath9k_htc_txcompletion_cb(hif_dev->htc_handle,
-                                          skb, 1);
-                TX_STAT_INC(skb_completed);
-        }
+        ath9k_skb_queue_complete(hif_dev, &tx_buf->skb_queue, txok);
 
-add_free:
         /* Re-initialize the SKB queue */
         tx_buf->len = tx_buf->offset = 0;
         __skb_queue_head_init(&tx_buf->skb_queue);
@@ -272,7 +259,7 @@ static int __hif_usb_tx(struct hif_device_usb *hif_dev)
         ret = usb_submit_urb(tx_buf->urb, GFP_ATOMIC);
         if (ret) {
                 tx_buf->len = tx_buf->offset = 0;
-                ath9k_skb_queue_purge(hif_dev, &tx_buf->skb_queue);
+                ath9k_skb_queue_complete(hif_dev, &tx_buf->skb_queue, false);
                 __skb_queue_head_init(&tx_buf->skb_queue);
                 list_move_tail(&tx_buf->list, &hif_dev->tx.tx_buf);
                 hif_dev->tx.tx_buf_cnt++;
@@ -342,7 +329,7 @@ static void hif_usb_stop(void *hif_handle, u8 pipe_id)
         unsigned long flags;
 
         spin_lock_irqsave(&hif_dev->tx.tx_lock, flags);
-        ath9k_skb_queue_purge(hif_dev, &hif_dev->tx.tx_skb_queue);
+        ath9k_skb_queue_complete(hif_dev, &hif_dev->tx.tx_skb_queue, false);
         hif_dev->tx.tx_skb_cnt = 0;
         hif_dev->tx.flags |= HIF_USB_TX_STOP;
         spin_unlock_irqrestore(&hif_dev->tx.tx_lock, flags);
diff --git a/drivers/net/wireless/ath/ath9k/htc.h b/drivers/net/wireless/ath/ath9k/htc.h
index 45cf7557943..0d2e2b10358 100644
--- a/drivers/net/wireless/ath/ath9k/htc.h
+++ b/drivers/net/wireless/ath/ath9k/htc.h
@@ -271,6 +271,7 @@ struct ath9k_htc_tx {
         u8 flags;
         int queued_cnt;
         struct sk_buff_head tx_queue;
+        struct sk_buff_head tx_failed;
         DECLARE_BITMAP(tx_slot, MAX_TX_BUF_NUM);
         spinlock_t tx_lock;
 };
@@ -305,8 +306,8 @@ struct ath_tx_stats {
         u32 buf_queued;
         u32 buf_completed;
         u32 skb_queued;
-        u32 skb_completed;
-        u32 skb_dropped;
+        u32 skb_success;
+        u32 skb_failed;
         u32 cab_queued;
         u32 queue_stats[WME_NUM_AC];
 };
@@ -544,6 +545,7 @@ void ath9k_htc_check_stop_queues(struct ath9k_htc_priv *priv);
 void ath9k_htc_check_wake_queues(struct ath9k_htc_priv *priv);
 int ath9k_htc_tx_get_slot(struct ath9k_htc_priv *priv);
 void ath9k_htc_tx_clear_slot(struct ath9k_htc_priv *priv, int slot);
+void ath9k_htc_tx_drain(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_debug.c b/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
index 6fc6cb74936..91a486cca32 100644
--- a/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
+++ b/drivers/net/wireless/ath/ath9k/htc_drv_debug.c
@@ -88,11 +88,11 @@ static ssize_t read_file_xmit(struct file *file, char __user *user_buf,
                         "%20s : %10u\n", "SKBs queued",
                         priv->debug.tx_stats.skb_queued);
         len += snprintf(buf + len, sizeof(buf) - len,
-                        "%20s : %10u\n", "SKBs completed",
-                        priv->debug.tx_stats.skb_completed);
+                        "%20s : %10u\n", "SKBs success",
+                        priv->debug.tx_stats.skb_success);
         len += snprintf(buf + len, sizeof(buf) - len,
-                        "%20s : %10u\n", "SKBs dropped",
-                        priv->debug.tx_stats.skb_dropped);
+                        "%20s : %10u\n", "SKBs failed",
+                        priv->debug.tx_stats.skb_failed);
         len += snprintf(buf + len, sizeof(buf) - len,
                         "%20s : %10u\n", "CAB queued",
                         priv->debug.tx_stats.cab_queued);
diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_gpio.c b/drivers/net/wireless/ath/ath9k/htc_drv_gpio.c
index 92e4b312a98..dc0b33d0121 100644
--- a/drivers/net/wireless/ath/ath9k/htc_drv_gpio.c
+++ b/drivers/net/wireless/ath/ath9k/htc_drv_gpio.c
@@ -429,9 +429,8 @@ void ath9k_htc_radio_disable(struct ieee80211_hw *hw)
 
         /* Stop TX */
         ieee80211_stop_queues(hw);
-        htc_stop(priv->htc);
+        ath9k_htc_tx_drain(priv);
         WMI_CMD(WMI_DRAIN_TXQ_ALL_CMDID);
-        skb_queue_purge(&priv->tx.tx_queue);
 
         /* Stop RX */
         WMI_CMD(WMI_STOP_RECV_CMDID);
diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_main.c b/drivers/net/wireless/ath/ath9k/htc_drv_main.c
index c7e056b40e1..fb9ff1188a0 100644
--- a/drivers/net/wireless/ath/ath9k/htc_drv_main.c
+++ b/drivers/net/wireless/ath/ath9k/htc_drv_main.c
@@ -193,7 +193,9 @@ void ath9k_htc_reset(struct ath9k_htc_priv *priv)
 
         ath9k_htc_stop_ani(priv);
         ieee80211_stop_queues(priv->hw);
-        htc_stop(priv->htc);
+
+        ath9k_htc_tx_drain(priv);
+
         WMI_CMD(WMI_DISABLE_INTR_CMDID);
         WMI_CMD(WMI_DRAIN_TXQ_ALL_CMDID);
         WMI_CMD(WMI_STOP_RECV_CMDID);
@@ -248,7 +250,9 @@ static int ath9k_htc_set_channel(struct ath9k_htc_priv *priv,
         fastcc = !!(hw->conf.flags & IEEE80211_CONF_OFFCHANNEL);
 
         ath9k_htc_ps_wakeup(priv);
-        htc_stop(priv->htc);
+
+        ath9k_htc_tx_drain(priv);
+
         WMI_CMD(WMI_DISABLE_INTR_CMDID);
         WMI_CMD(WMI_DRAIN_TXQ_ALL_CMDID);
         WMI_CMD(WMI_STOP_RECV_CMDID);
@@ -263,6 +267,7 @@ static int ath9k_htc_set_channel(struct ath9k_htc_priv *priv,
 
         if (!fastcc)
                 caldata = &priv->caldata;
+
         ret = ath9k_hw_reset(ah, hchan, caldata, fastcc);
         if (ret) {
                 ath_err(common,
@@ -960,16 +965,14 @@ static void ath9k_htc_stop(struct ieee80211_hw *hw)
         }
 
         ath9k_htc_ps_wakeup(priv);
-        htc_stop(priv->htc);
+
         WMI_CMD(WMI_DISABLE_INTR_CMDID);
         WMI_CMD(WMI_DRAIN_TXQ_ALL_CMDID);
         WMI_CMD(WMI_STOP_RECV_CMDID);
 
         tasklet_kill(&priv->rx_tasklet);
-        tasklet_kill(&priv->tx_tasklet);
-
-        skb_queue_purge(&priv->tx.tx_queue);
 
+        ath9k_htc_tx_drain(priv);
         ath9k_wmi_event_drain(priv);
 
         mutex_unlock(&priv->mutex);
diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_txrx.c b/drivers/net/wireless/ath/ath9k/htc_drv_txrx.c
index 944440c84c4..9e0c34b0a79 100644
--- a/drivers/net/wireless/ath/ath9k/htc_drv_txrx.c
+++ b/drivers/net/wireless/ath/ath9k/htc_drv_txrx.c
@@ -423,6 +423,26 @@ send_mac80211:
         ieee80211_tx_status(priv->hw, skb);
 }
 
+void ath9k_htc_tx_drain(struct ath9k_htc_priv *priv)
+{
+        struct sk_buff *skb = NULL;
+
+        /*
+         * Ensure that all pending TX frames are flushed,
+         * and that the TX completion tasklet is killed.
+         */
+        htc_stop(priv->htc);
+        tasklet_kill(&priv->tx_tasklet);
+
+        while ((skb = skb_dequeue(&priv->tx.tx_queue)) != NULL) {
+                ath9k_htc_tx_process(priv, skb);
+        }
+
+        while ((skb = skb_dequeue(&priv->tx.tx_failed)) != NULL) {
+                ath9k_htc_tx_process(priv, skb);
+        }
+}
+
 void ath9k_tx_tasklet(unsigned long data)
 {
         struct ath9k_htc_priv *priv = (struct ath9k_htc_priv *)data;
@@ -432,6 +452,10 @@ void ath9k_tx_tasklet(unsigned long data)
                 ath9k_htc_tx_process(priv, skb);
         }
 
+        while ((skb = skb_dequeue(&priv->tx.tx_failed)) != NULL) {
+                ath9k_htc_tx_process(priv, skb);
+        }
+
         /* Wake TX queues if needed */
         ath9k_htc_check_wake_queues(priv);
 }
@@ -445,13 +469,18 @@ void ath9k_htc_txep(void *drv_priv, struct sk_buff *skb,
         tx_ctl = HTC_SKB_CB(skb);
         tx_ctl->txok = txok;
 
-        skb_queue_tail(&priv->tx.tx_queue, skb);
+        if (txok)
+                skb_queue_tail(&priv->tx.tx_queue, skb);
+        else
+                skb_queue_tail(&priv->tx.tx_failed, skb);
+
         tasklet_schedule(&priv->tx_tasklet);
 }
 
 int ath9k_tx_init(struct ath9k_htc_priv *priv)
 {
         skb_queue_head_init(&priv->tx.tx_queue);
+        skb_queue_head_init(&priv->tx.tx_failed);
         return 0;
 }