[PATCH] 8139too: Rx fifo/overflow recovery

From: Francois Romieu <romieu@fr.zoreil.com>

This patch allows to update the interrupt status register after an Rx
overflow or a Rx fifo error even when the Rx buffer contains no packet.
The update must be kept in the packet processing loop to prevent an Rx
error storm.  As an interesting behavior, the status of the interrupt
status register must not be read early.
Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>

drivers/net/8139too.c

@@ -1927,6 +1927,24 @@ static __inline__ void wrap_copy(struct sk_buff *skb, const unsigned char *ring,
 }
 #endif
 
+static void rtl8139_isr_ack(struct rtl8139_private *tp)
+{
+	void *ioaddr = tp->mmio_addr;
+	u16 status;
+
+	status = RTL_R16 (IntrStatus) & RxAckBits;
+
+	/* Clear out errors and receive interrupts */
+	if (likely(status != 0)) {
+		if (unlikely(status & (RxFIFOOver | RxOverflow))) {
+			tp->stats.rx_errors++;
+			if (status & RxFIFOOver)
+				tp->stats.rx_fifo_errors++;
+		}
+		RTL_W16_F (IntrStatus, RxAckBits);
+	}
+}
+
 static int rtl8139_rx(struct net_device *dev, struct rtl8139_private *tp,
 		      int budget)
 {
@@ -1934,6 +1952,7 @@ static int rtl8139_rx(struct net_device *dev, struct rtl8139_private *tp,
 	int received = 0;
 	unsigned char *rx_ring = tp->rx_ring;
 	unsigned int cur_rx = tp->cur_rx;
+	unsigned int rx_size = 0;
 
 	DPRINTK ("%s: In rtl8139_rx(), current %4.4x BufAddr %4.4x,"
 		 " free to %4.4x, Cmd %2.2x.\n", dev->name, cur_rx,
@@ -1944,10 +1963,8 @@ static int rtl8139_rx(struct net_device *dev, struct rtl8139_private *tp,
 	       && (RTL_R8 (ChipCmd) & RxBufEmpty) == 0) {
 		u32 ring_offset = cur_rx % RX_BUF_LEN;
 		u32 rx_status;
-		unsigned int rx_size;
 		unsigned int pkt_size;
 		struct sk_buff *skb;
-		u16 status;
 
 		rmb();
 
@@ -1977,7 +1994,7 @@ static int rtl8139_rx(struct net_device *dev, struct rtl8139_private *tp,
 		 */
 		if (unlikely(rx_size == 0xfff0)) {
 			tp->xstats.early_rx++;
-			goto done;
+			break;
 		}
 
 		/* If Rx err or invalid rx_size/rx_status received
@@ -1989,7 +2006,8 @@ static int rtl8139_rx(struct net_device *dev, struct rtl8139_private *tp,
 			     (rx_size < 8) ||
 			     (!(rx_status & RxStatusOK)))) {
 			rtl8139_rx_err (rx_status, dev, tp, ioaddr);
-			return -1;
+			received = -1;
+			goto out;
 		}
 
 		/* Malloc up new buffer, compatible with net-2e. */
@@ -2025,19 +2043,11 @@ static int rtl8139_rx(struct net_device *dev, struct rtl8139_private *tp,
 		cur_rx = (cur_rx + rx_size + 4 + 3) & ~3;
 		RTL_W16 (RxBufPtr, (u16) (cur_rx - 16));
 
-		/* Clear out errors and receive interrupts */
-		status = RTL_R16 (IntrStatus) & RxAckBits;
-		if (likely(status != 0)) {
-			if (unlikely(status & (RxFIFOOver | RxOverflow))) {
-				tp->stats.rx_errors++;
-				if (status & RxFIFOOver)
-					tp->stats.rx_fifo_errors++;
-			}
-			RTL_W16_F (IntrStatus, RxAckBits);
-		}
+		rtl8139_isr_ack(tp);
 	}
 
- done:
+	if (unlikely(!received || rx_size == 0xfff0))
+		rtl8139_isr_ack(tp);
 
 #if RTL8139_DEBUG > 1
 	DPRINTK ("%s: Done rtl8139_rx(), current %4.4x BufAddr %4.4x,"
@@ -2047,6 +2057,7 @@ static int rtl8139_rx(struct net_device *dev, struct rtl8139_private *tp,
 #endif
 
 	tp->cur_rx = cur_rx;
+out:
 	return received;
 }