p54: fix queue stall due to underrun

Larry Finger discovered a weird behavior under load.
In essence, the queue's length count under runs,
which in turn renders the associated ac queue unusable.

Reported-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Christian Lamparter <chunkeey@web.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/net/wireless/p54/txrx.c b/drivers/net/wireless/p54/txrx.c
index 31fda17bec43..6426d2cae6de 100644
--- a/drivers/net/wireless/p54/txrx.c
+++ b/drivers/net/wireless/p54/txrx.c
@@ -199,7 +199,7 @@ static int p54_tx_qos_accounting_alloc(struct p54_common *priv,
         queue = &priv->tx_stats[p54_queue];
 
         spin_lock_irqsave(&priv->tx_stats_lock, flags);
-        if (unlikely(queue->len > queue->limit && IS_QOS_QUEUE(p54_queue))) {
+        if (unlikely(queue->len >= queue->limit && IS_QOS_QUEUE(p54_queue))) {
                 spin_unlock_irqrestore(&priv->tx_stats_lock, flags);
                 return -ENOSPC;
         }
@@ -222,8 +222,11 @@ static void p54_tx_qos_accounting_free(struct p54_common *priv,
         if (skb && IS_DATA_FRAME(skb)) {
                 struct p54_hdr *hdr = (void *) skb->data;
                 struct p54_tx_data *data = (void *) hdr->data;
+                unsigned long flags;
 
+                spin_lock_irqsave(&priv->tx_stats_lock, flags);
                 priv->tx_stats[data->hw_queue].len--;
+                spin_unlock_irqrestore(&priv->tx_stats_lock, flags);
         }
         p54_wake_queues(priv);
 }
@@ -462,7 +465,6 @@ static void p54_rx_eeprom_readback(struct p54_common *priv,
 
         priv->eeprom = NULL;
         tmp = p54_find_and_unlink_skb(priv, hdr->req_id);
-        p54_tx_qos_accounting_free(priv, tmp);
         dev_kfree_skb_any(tmp);
         complete(&priv->eeprom_comp);
 }
@@ -489,7 +491,6 @@ static void p54_rx_stats(struct p54_common *priv, struct sk_buff *skb)
         priv->noise = p54_rssi_to_dbm(priv, le32_to_cpu(stats->noise));
 
         tmp = p54_find_and_unlink_skb(priv, hdr->req_id);
-        p54_tx_qos_accounting_free(priv, tmp);
         dev_kfree_skb_any(tmp);
 }