[PATCH] (13/23) sk98: handle ring full correctly

[Stephen Hemminger <shemminger@xxxxxxxx>]

This driver needs to manage it's transmit queue properly.
The hard_start_xmit needs to return OK if send successfully
and BUSY (1) if queue is full. In either case must free skb,
existing code would leak if tx ring filled!

Also, check if queue is send fills queue and stop transmit queue 
as needed. In order to test for ring full w/o race, pull locking 
up from XmitFrame to SkGeXmit

Signed-off-by: Stephen Hemminger<shemminger@xxxxxxxx>

diff -Nru a/drivers/net/sk98lin/skge.c b/drivers/net/sk98lin/skge.c
--- a/drivers/net/sk98lin/skge.c        2004-11-03 15:56:39 -08:00
+++ b/drivers/net/sk98lin/skge.c        2004-11-03 15:56:39 -08:00
@@ -1396,59 +1396,43 @@
  * Returns:
  *     0, if everything is ok
  *     !=0, on error
- * WARNING: returning 1 in 'tbusy' case caused system crashes (double
- *     allocated skb's) !!!
  */
 static int SkGeXmit(struct sk_buff *skb, struct net_device *dev)
 {
-DEV_NET                *pNet;
-SK_AC          *pAC;
-int                    Rc;     /* return code of XmitFrame */
-
-       pNet = netdev_priv(dev);
-       pAC = pNet->pAC;
+       DEV_NET *pNet = netdev_priv(dev);
+       SK_AC   *pAC = pNet->pAC;
+       TX_PORT         *pTxPort;
+       int     rc;
+       unsigned long flags;
+
+       if (pAC->RlmtNets == 2)
+               pTxPort = &pAC->TxPort[pNet->PortNr][TX_PRIO_LOW];
+       else
+               pTxPort = &pAC->TxPort[pAC->ActivePort][TX_PRIO_LOW];
 
+       spin_lock_irqsave(&pTxPort->TxDesRingLock, flags);
        if ((!skb_shinfo(skb)->nr_frags) ||
                (pAC->GIni.GIChipId == CHIP_ID_GENESIS)) {
                /* Don't activate scatter-gather and hardware checksum */
-
-               if (pAC->RlmtNets == 2)
-                       Rc = XmitFrame(
-                               pAC,
-                               &pAC->TxPort[pNet->PortNr][TX_PRIO_LOW],
-                               skb);
-               else
-                       Rc = XmitFrame(
-                               pAC,
-                               &pAC->TxPort[pAC->ActivePort][TX_PRIO_LOW],
-                               skb);
+               rc = XmitFrame( pAC, pTxPort, skb);
        } else {
-               /* scatter-gather and hardware TCP checksumming anabled*/
-               if (pAC->RlmtNets == 2)
-                       Rc = XmitFrameSG(
-                               pAC,
-                               &pAC->TxPort[pNet->PortNr][TX_PRIO_LOW],
-                               skb);
-               else
-                       Rc = XmitFrameSG(
-                               pAC,
-                               &pAC->TxPort[pAC->ActivePort][TX_PRIO_LOW],
-                               skb);
+               rc = XmitFrameSG(pAC, pTxPort, skb);
        }
 
-       /* Transmitter out of resources? */
-       if (Rc <= 0) {
+       /* No space left for next transmit */
+       if (rc <= 0) 
                netif_stop_queue(dev);
-       }
 
-       /* If not taken, give buffer ownership back to the
-        * queueing layer.
-        */
-       if (Rc < 0)
-               return (1);
+       spin_unlock_irqrestore(&pTxPort->TxDesRingLock, flags);
 
-       dev->trans_start = jiffies;
-       return (0);
+       /* Transmit failed, out of resources */
+       if (rc < 0) {
+               dev_kfree_skb(skb);
+               return NETDEV_TX_BUSY;
+       } else {
+               dev->trans_start = jiffies;             
+               return NETDEV_TX_OK;
+       }
 } /* SkGeXmit */
 
 
@@ -1481,7 +1465,6 @@
 {
        TXD             *pTxd;          /* the rxd to fill */
        TXD             *pOldTxd;
-       unsigned long    Flags;
        SK_U64           PhysAddr;
        int              Protocol;
        int              IpHeaderLength;
@@ -1489,7 +1472,6 @@
 
        SK_DBG_MSG(NULL, SK_DBGMOD_DRV, SK_DBGCAT_DRV_TX_PROGRESS, ("X"));
 
-       spin_lock_irqsave(&pTxPort->TxDesRingLock, Flags);
 #ifndef USE_TX_COMPLETE
        FreeTxDescriptors(pAC, pTxPort);
 #endif
@@ -1500,7 +1482,6 @@
                */
                FreeTxDescriptors(pAC, pTxPort);
                if (pTxPort->TxdRingFree == 0) {
-                       spin_unlock_irqrestore(&pTxPort->TxDesRingLock, Flags);
                        SK_PNMI_CNT_NO_TX_BUF(pAC, pTxPort->PortIndex);
                        SK_DBG_MSG(NULL, SK_DBGMOD_DRV,
                                SK_DBGCAT_DRV_TX_PROGRESS,
@@ -1523,7 +1504,6 @@
        */
        if (BytesSend < C_LEN_ETHERNET_MINSIZE) {
                if ((pMessage = skb_padto(pMessage, C_LEN_ETHERNET_MINSIZE)) == 
NULL) {
-                       spin_unlock_irqrestore(&pTxPort->TxDesRingLock, Flags);
                        return 0;
                }
                pMessage->len = C_LEN_ETHERNET_MINSIZE;
@@ -1598,16 +1578,7 @@
                SK_OUT8(pTxPort->HwAddr, Q_CSR, CSR_START);
        }       
 
-       /* 
-       ** after releasing the lock, the skb may immediately be free'd 
-       */
-       spin_unlock_irqrestore(&pTxPort->TxDesRingLock, Flags);
-       if (pTxPort->TxdRingFree != 0) {
-               return (BytesSend);
-       } else {
-               return (0);
-       }
-
+       return (pTxPort->TxdRingFree != 0);
 } /* XmitFrame */
 
 /*****************************************************************************
@@ -1640,16 +1611,13 @@
        int              Protocol;
        skb_frag_t      *sk_frag;
        SK_U64           PhysAddr;
-       unsigned long    Flags;
 
-       spin_lock_irqsave(&pTxPort->TxDesRingLock, Flags);
 #ifndef USE_TX_COMPLETE
        FreeTxDescriptors(pAC, pTxPort);
 #endif
        if ((skb_shinfo(pMessage)->nr_frags +1) > pTxPort->TxdRingFree) {
                FreeTxDescriptors(pAC, pTxPort);
                if ((skb_shinfo(pMessage)->nr_frags + 1) > 
pTxPort->TxdRingFree) {
-                       spin_unlock_irqrestore(&pTxPort->TxDesRingLock, Flags);
                        SK_PNMI_CNT_NO_TX_BUF(pAC, pTxPort->PortIndex);
                        SK_DBG_MSG(NULL, SK_DBGMOD_DRV,
                                SK_DBGCAT_DRV_TX_PROGRESS,
@@ -1781,13 +1749,7 @@
        pTxPort->pTxdRingPrev = pTxdLst;
        pTxPort->pTxdRingHead = pTxd;
 
-       spin_unlock_irqrestore(&pTxPort->TxDesRingLock, Flags);
-
-       if (pTxPort->TxdRingFree > 0) {
-               return (BytesSend);
-       } else {
-               return (0);
-       }
+       return (pTxPort->TxdRingFree > 0);
 }
 
 /*****************************************************************************