2009-07-06 13:18:12

by Christian Lamparter

[permalink] [raw]
Subject: [PATCH] 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 <[email protected]>
Signed-off-by: Christian Lamparter <[email protected]>
---
diff --git a/drivers/net/wireless/p54/txrx.c b/drivers/net/wireless/p54/txrx.c
index ea074a6..01eadb1 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);
}
@@ -504,7 +507,6 @@ 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);
}
@@ -531,7 +533,6 @@ 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);
}