[PATCH 2.6.9-rc1-mm4 1/4] r8169: miscalculation of available Tx descriptors

[Francois Romieu <romieu@xxxxxxxxxxxxx>]

The count of available entries in the Tx descriptors ring is badly wrong.

Signed-off-by: Francois Romieu <romieu@xxxxxxxxxxxxx>

diff -puN drivers/net/r8169.c~r8169-130 drivers/net/r8169.c
--- linux-2.6.9-rc1/drivers/net/r8169.c~r8169-130       2004-09-08 
22:02:35.000000000 +0200
+++ linux-2.6.9-rc1-fr/drivers/net/r8169.c      2004-09-08 22:02:35.000000000 
+0200
@@ -77,6 +77,9 @@ VERSION 1.6LK <2004/04/14>
 #define dprintk(fmt, args...)  do {} while (0)
 #endif /* RTL8169_DEBUG */
 
+#define TX_BUFFS_AVAIL(tp) \
+       (tp->dirty_tx + NUM_TX_DESC - tp->cur_tx - 1)
+
 #ifdef CONFIG_R8169_NAPI
 #define rtl8169_rx_skb                 netif_receive_skb
 #define rtl8169_rx_hwaccel_skb         vlan_hwaccel_rx
@@ -1766,8 +1769,7 @@ static int rtl8169_start_xmit(struct sk_
        u32 status, len;
        u32 opts1;
        
-       if (unlikely(tp->cur_tx - tp->dirty_tx < skb_shinfo(skb)->nr_frags)) {
-               netif_stop_queue(dev);
+       if (unlikely(TX_BUFFS_AVAIL(tp) < skb_shinfo(skb)->nr_frags)) {
                printk(KERN_ERR PFX "%s: BUG! Tx Ring full when queue awake!\n",
                       dev->name);
                return 1;
@@ -1816,10 +1818,10 @@ static int rtl8169_start_xmit(struct sk_
 
        RTL_W8(TxPoll, 0x40);   //set polling bit
 
-       if (tp->cur_tx - tp->dirty_tx < MAX_SKB_FRAGS) {
+       if (TX_BUFFS_AVAIL(tp) < MAX_SKB_FRAGS) {
                netif_stop_queue(dev);
                smp_rmb();
-               if (tp->cur_tx - tp->dirty_tx >= MAX_SKB_FRAGS)
+               if (TX_BUFFS_AVAIL(tp) >= MAX_SKB_FRAGS)
                        netif_wake_queue(dev);
        }
 
@@ -1874,8 +1876,10 @@ rtl8169_tx_interrupt(struct net_device *
        if (tp->dirty_tx != dirty_tx) {
                tp->dirty_tx = dirty_tx;
                smp_wmb();
-               if (netif_queue_stopped(dev))
+               if (netif_queue_stopped(dev) &&
+                   (TX_BUFFS_AVAIL(tp) >= MAX_SKB_FRAGS)) {
                        netif_wake_queue(dev);
+               }
        }
 }
 

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