[Qemu-devel] [PATCH] ehci: fix infinite loop with usb netdevice

[David S. Ahern]

Hi Jan:

The attached addresses the spinning with the usb net device. Now I can
enable the device and ethtool shows a link:

# ifconfig usb0 up
# ethtool usb0
Settings for usb0:
        Current message level: 0x00000007 (7)
        Link detected: yes

Though dhclient still can't get an address. After a bit of
instrumentation it appears that packets are lost in the receive the path
somewhere:

usb0      Link encap:Ethernet  HWaddr 42:5F:CA:51:54:77
          BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:25 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 b)  TX bytes:5513 (5.3 KiB)

I looked at an x3650M2 with an IMM. It has a usb-based ethernet device.
I compared the output of lsusb -v from the IMM with the qemu usb net
device and nothing jumps out -- other than the fact that the IMM's
network device shows up on a uhci bus.

David

diff --git a/hw/usb-ehci.c b/hw/usb-ehci.c
index f806a20..218d590 100644
--- a/hw/usb-ehci.c
+++ b/hw/usb-ehci.c
@@ -981,13 +981,15 @@ err:
             qh->token |= QTD_TOKEN_HALT;
             break;
         case USB_RET_NAK:
+            /* 4.10.3 */
             reload = get_field(qh->epchar, QH_EPCHAR_RL);
             if ((ehci->pid == USB_TOKEN_IN) && reload) {
                 int nakcnt = get_field(qh->altnext_qtd, QH_ALTNEXT_NAKCNT);
                 nakcnt--;
                 set_field(&qh->altnext_qtd, nakcnt, QH_ALTNEXT_NAKCNT);
+            } else if (!reload) {
+                return USB_RET_NAK;
             }
-            return USB_RET_NAK;
             break;
         case USB_RET_BABBLE:
             fprintf(stderr, "USB babble TODO\n");
@@ -1040,7 +1042,7 @@ err:
 
         ret += ehci->more;
 
-        if (ret > ehci->tbytes) {
+        if ((ret > ehci->tbytes) && (ehci->pid == USB_TOKEN_IN)) {
             ret = USB_RET_BABBLE;
             goto err;
         }