DM9000: fix interface hang under load

When transferring data at full speed, the DM9000 network interface
sometimes stops sending/receiving data. Worse, ksoftirqd consumes
100% cpu and the net tx watchdog never triggers.
Fix by spin_lock_irqsave() in dm9000_start_xmit() to prevent the
interrupt handler from interfering.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

diff --git a/drivers/net/dm9000.c b/drivers/net/dm9000.c
index c3de81b..738aa59 100644 (file)
--- a/drivers/net/dm9000.c
+++ b/drivers/net/dm9000.c
@@ -700,6 +700,7 @@ dm9000_init_dm9000(struct net_device *dev)
 static int
 dm9000_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
+       unsigned long flags;
        board_info_t *db = (board_info_t *) dev->priv;
 
        PRINTK3("dm9000_start_xmit\n");
@@ -707,10 +708,7 @@ dm9000_start_xmit(struct sk_buff *skb, struct net_device *dev)
        if (db->tx_pkt_cnt > 1)
                return 1;
 
-       netif_stop_queue(dev);
-
-       /* Disable all interrupts */
-       iow(db, DM9000_IMR, IMR_PAR);
+       spin_lock_irqsave(&db->lock, flags);
 
        /* Move data to DM9000 TX RAM */
        writeb(DM9000_MWCMD, db->io_addr);
@@ -718,12 +716,9 @@ dm9000_start_xmit(struct sk_buff *skb, struct net_device *dev)
        (db->outblk)(db->io_data, skb->data, skb->len);
        db->stats.tx_bytes += skb->len;
 
+       db->tx_pkt_cnt++;
        /* TX control: First packet immediately send, second packet queue */
-       if (db->tx_pkt_cnt == 0) {
-
-               /* First Packet */
-               db->tx_pkt_cnt++;
-
+       if (db->tx_pkt_cnt == 1) {
                /* Set TX length to DM9000 */
                iow(db, DM9000_TXPLL, skb->len & 0xff);
                iow(db, DM9000_TXPLH, (skb->len >> 8) & 0xff);
@@ -732,23 +727,17 @@ dm9000_start_xmit(struct sk_buff *skb, struct net_device *dev)
                iow(db, DM9000_TCR, TCR_TXREQ); /* Cleared after TX complete */
 
                dev->trans_start = jiffies;     /* save the time stamp */
-
        } else {
                /* Second packet */
-               db->tx_pkt_cnt++;
                db->queue_pkt_len = skb->len;
+               netif_stop_queue(dev);
        }
 
+       spin_unlock_irqrestore(&db->lock, flags);
+
        /* free this SKB */
        dev_kfree_skb(skb);
 
-       /* Re-enable resource check */
-       if (db->tx_pkt_cnt == 1)
-               netif_wake_queue(dev);
-
-       /* Re-enable interrupt */
-       iow(db, DM9000_IMR, IMR_PAR | IMR_PTM | IMR_PRM);
-
        return 0;
 }