p54: enforce strict tx_queue limits

The patch fixes an old FIXME in p54pci.c by moving the "queue full"
check into the common library, where we can deal with it properly.

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

2 files changed, 21 insertions, 8 deletions

diff --git a/drivers/net/wireless/p54/p54common.c b/drivers/net/wireless/p54/p54common.c
index 409ae930d766..fac6b416e9e9 100644
--- a/drivers/net/wireless/p54/p54common.c
+++ b/drivers/net/wireless/p54/p54common.c
@@ -874,7 +874,27 @@ static int p54_assign_address(struct ieee80211_hw *dev, struct sk_buff *skb,
                 return -EINVAL;
 
         spin_lock_irqsave(&priv->tx_queue.lock, flags);
+
         left = skb_queue_len(&priv->tx_queue);
+        if (unlikely(left >= 28)) {
+                /*
+                 * The tx_queue is nearly full!
+                 * We have throttle normal data traffic, because we must
+                 * have a few spare slots for control frames left.
+                 */
+                ieee80211_stop_queues(dev);
+
+                if (unlikely(left == 32)) {
+                        /*
+                         * The tx_queue is now really full.
+                         *
+                         * TODO: check if the device has crashed and reset it.
+                         */
+                        spin_unlock_irqrestore(&priv->tx_queue.lock, flags);
+                        return -ENOSPC;
+                }
+        }
+
         while (left--) {
                 u32 hole_size;
                 info = IEEE80211_SKB_CB(entry);
@@ -903,7 +923,7 @@ static int p54_assign_address(struct ieee80211_hw *dev, struct sk_buff *skb,
         if (!target_skb) {
                 spin_unlock_irqrestore(&priv->tx_queue.lock, flags);
                 ieee80211_stop_queues(dev);
-                return -ENOMEM;
+                return -ENOSPC;
         }
 
         info = IEEE80211_SKB_CB(skb);
diff --git a/drivers/net/wireless/p54/p54pci.c b/drivers/net/wireless/p54/p54pci.c
index d21c509325fe..c28220e401b9 100644
--- a/drivers/net/wireless/p54/p54pci.c
+++ b/drivers/net/wireless/p54/p54pci.c
@@ -332,13 +332,6 @@ static void p54p_tx(struct ieee80211_hw *dev, struct sk_buff *skb,
 
         P54P_WRITE(dev_int, cpu_to_le32(ISL38XX_DEV_INT_UPDATE));
         P54P_READ(dev_int);
-
-        /* FIXME: unlikely to happen because the device usually runs out of
-           memory before we fill the ring up, but we can make it impossible */
-        if (idx - device_idx > ARRAY_SIZE(ring_control->tx_data) - 2) {
-                p54_free_skb(dev, skb);
-                printk(KERN_INFO "%s: tx overflow.\n", wiphy_name(dev->wiphy));
-        }
 }
 
 static void p54p_stop(struct ieee80211_hw *dev)