pch_gbe: replace private tx ring lock with common netif_tx_lock

pch_gbe_tx_ring.tx_lock is only used in the hard_xmit handler and
in the transmit completion reaper called from NAPI context.

Compile-tested only. Potential victims Cced.

Someone more knowledgeable may check if pch_gbe_tx_queue could
have some use for a mmiowb.
Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Cc: Darren Hart <dvhart@infradead.org>
Cc: Andy Cress <andy.cress@us.kontron.com>
Cc: bryan@fossetcon.org
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/oki-semi/pch_gbe/pch_gbe.h

@@ -481,7 +481,6 @@ struct pch_gbe_buffer {
 
 /**
  * struct pch_gbe_tx_ring - tx ring information
- * @tx_lock:	spinlock structs
  * @desc:	pointer to the descriptor ring memory
  * @dma:	physical address of the descriptor ring
  * @size:	length of descriptor ring in bytes
@@ -491,7 +490,6 @@ struct pch_gbe_buffer {
  * @buffer_info:	array of buffer information structs
  */
 struct pch_gbe_tx_ring {
-	spinlock_t tx_lock;
 	struct pch_gbe_tx_desc *desc;
 	dma_addr_t dma;
 	unsigned int size;

drivers/net/ethernet/oki-semi/pch_gbe/pch_gbe_main.c

@@ -1640,7 +1640,7 @@ pch_gbe_clean_tx(struct pch_gbe_adapter *adapter,
 		   cleaned_count);
 	if (cleaned_count > 0)  { /*skip this if nothing cleaned*/
 		/* Recover from running out of Tx resources in xmit_frame */
-		spin_lock(&tx_ring->tx_lock);
+		netif_tx_lock(adapter->netdev);
 		if (unlikely(cleaned && (netif_queue_stopped(adapter->netdev))))
 		{
 			netif_wake_queue(adapter->netdev);
@@ -1652,7 +1652,7 @@ pch_gbe_clean_tx(struct pch_gbe_adapter *adapter,
 
 		netdev_dbg(adapter->netdev, "next_to_clean : %d\n",
 			   tx_ring->next_to_clean);
-		spin_unlock(&tx_ring->tx_lock);
+		netif_tx_unlock(adapter->netdev);
 	}
 	return cleaned;
 }
@@ -1805,7 +1805,6 @@ int pch_gbe_setup_tx_resources(struct pch_gbe_adapter *adapter,
 
 	tx_ring->next_to_use = 0;
 	tx_ring->next_to_clean = 0;
-	spin_lock_init(&tx_ring->tx_lock);
 
 	for (desNo = 0; desNo < tx_ring->count; desNo++) {
 		tx_desc = PCH_GBE_TX_DESC(*tx_ring, desNo);
@@ -2135,13 +2134,9 @@ static int pch_gbe_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
 {
 	struct pch_gbe_adapter *adapter = netdev_priv(netdev);
 	struct pch_gbe_tx_ring *tx_ring = adapter->tx_ring;
-	unsigned long flags;
-
-	spin_lock_irqsave(&tx_ring->tx_lock, flags);
 
 	if (unlikely(!PCH_GBE_DESC_UNUSED(tx_ring))) {
 		netif_stop_queue(netdev);
-		spin_unlock_irqrestore(&tx_ring->tx_lock, flags);
 		netdev_dbg(netdev,
 			   "Return : BUSY  next_to use : 0x%08x  next_to clean : 0x%08x\n",
 			   tx_ring->next_to_use, tx_ring->next_to_clean);
@@ -2150,7 +2145,6 @@ static int pch_gbe_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
 
 	/* CRC,ITAG no support */
 	pch_gbe_tx_queue(adapter, tx_ring, skb);
-	spin_unlock_irqrestore(&tx_ring->tx_lock, flags);
 	return NETDEV_TX_OK;
 }