On 22.02.2012 08:05, Oliver Hartkopp wrote:

Feb 21 20:27:10 vwagwolkf484 kernel: [ 3162.519539] peak_usb 2-1.3:1.0: can3: Tx URB aborted (-71)
Feb 21 20:27:10 vwagwolkf484 kernel: [ 3162.519592] peak_usb 2-1.3:1.0: can2: Tx URB aborted (-71)
Feb 21 20:27:10 vwagwolkf484 kernel: [ 3162.519632] peak_usb 2-1.3:1.0: can_put_echo_skb: BUG! echo_skb is occupied!
Feb 21 20:27:10 vwagwolkf484 kernel: [ 3162.519707] peak_usb 2-1.3:1.0: can3: Rx URB aborted (-71)
Feb 21 20:27:10 vwagwolkf484 kernel: [ 3162.519746] peak_usb 2-1.3:1.0: can_put_echo_skb: BUG! echo_skb is occupied!

(..)

Feb 21 20:27:10 vwagwolkf484 kernel: [ 3162.615114] peak_usb 2-1.3:1.0: can2: Tx URB aborted (-108)
Feb 21 20:27:10 vwagwolkf484 kernel: [ 3162.615117] peak_usb 2-1.3:1.0: can_put_echo_skb: BUG! echo_skb is occupied!
Feb 21 20:27:10 vwagwolkf484 kernel: [ 3162.615120] peak_usb 2-1.3:1.0: can2: Tx URB aborted (-108)
Feb 21 20:27:10 vwagwolkf484 kernel: [ 3162.615124] peak_usb 2-1.3:1.0: can_put_echo_skb: BUG! echo_skb is occupied!
Feb 21 20:27:10 vwagwolkf484 kernel: [ 3162.615130] peak_usb 2-1.3:1.0: can_put_echo_skb: BUG! echo_skb is occupied!
Feb 21 20:27:10 vwagwolkf484 kernel: [ 3162.623962] peak_usb 2-1.3:1.0: can3: Tx URB aborted (-108)
Feb 21 20:27:10 vwagwolkf484 kernel: [ 3162.623969] peak_usb 2-1.3:1.0: can3: Tx URB aborted (-108)

-71  => EPROTO          71      /* Protocol error */
-108 => ESHUTDOWN       108     /* Cannot send after transport endpoint shutdown */

+/*
+ * callback for bulk Tx urb
+ */
+static void peak_usb_write_bulk_callback(struct urb *urb)
+{
+       struct peak_tx_urb_context *context = urb->context;
+       struct peak_usb_device *dev;
+       struct net_device *netdev;
+
+       BUG_ON(!context);
+
+       dev = context->dev;
+       netdev = dev->netdev;
+
+       atomic_dec(&dev->active_tx_urbs);
+
+       if (!netif_device_present(netdev))
+               return;
+
+       switch (urb->status) {
+       case 0: /* tx ok */
+               netdev->trans_start = jiffies;
+
+               /* transmission complete interrupt */
+               netdev->stats.tx_packets++;
+               netdev->stats.tx_bytes += context->dlc;
+
+               can_get_echo_skb(netdev, context->echo_index);
+               break;
+
+       case -ENOENT: /* on ifconfig down */
+               break;
+       default:
+               netdev_err(netdev, "Tx URB aborted (%d)\n", urb->status);

Just printing this status and continue with business as usual (netif_wake_queue!) is probably not the right approach 8-)

Please check if it makes sense to check (urb->status != 0) earlier in this callback function.
 
+       }
+
+       /* release context */
+       context->echo_index = PCAN_USB_MAX_TX_URBS;
+
+       netif_wake_queue(netdev);
+}