[Qemu-devel] [PATCH 6/6] usb-ehci: Handle ISO packets failing with an error other then NAK

[Hans de Goede <hdegoede@redhat.com>]

Before this patch the ehci code was not checking for any other errors other
then USB_RET_NAK. This causes 2 problems:
1) Other errors are not reported to the guest.
2) When transactions with the ITD_XACT_IOC bit set completing with another
   error would not result in USBSTS_INT getting set.

I hit this problem when unplugging devices while iso data was streaming from
the device to the guest. When this happens it takes a while for the guest to
process the unplugging and remove ISO transactions from the ehci schedule, in
the mean time these transactions would complete with a result of USB_RET_NODEV,
which was not handled. This lead to the Linux guest's usb subsystem "hanging",
that is it would no longer see new usb devices getting plugged in and running
for example lsusb would lead to a stuck (D state) lsusb process. This patch
fixes this.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 hw/usb-ehci.c |   22 +++++++++++++++++++---
 1 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/hw/usb-ehci.c b/hw/usb-ehci.c
index 69bcc4b..a6b6ae5 100644
--- a/hw/usb-ehci.c
+++ b/hw/usb-ehci.c
@@ -1512,11 +1512,27 @@ static int ehci_process_itd(EHCIState *ehci,
                     /* IN */
                     set_field(&itd->transact[i], ret, ITD_XACT_LENGTH);
                 }
-
-                if (itd->transact[i] & ITD_XACT_IOC) {
-                    ehci_record_interrupt(ehci, USBSTS_INT);
+            } else {
+                switch (ret) {
+                default:
+                    fprintf(stderr, "Unexpected iso usb result: %d\n", ret);
+                    /* Fall through */
+                case USB_RET_NODEV:
+                    /* 3.3.2: XACTERR is only allowed on IN transactions */
+                    if (dir) {
+                        itd->transact[i] |= ITD_XACT_XACTERR;
+                        ehci_record_interrupt(ehci, USBSTS_ERRINT);
+                    }
+                    break;
+                case USB_RET_BABBLE:
+                    itd->transact[i] |= ITD_XACT_BABBLE;
+                    ehci_record_interrupt(ehci, USBSTS_ERRINT);
+                    break;
                 }
             }
+            if (itd->transact[i] & ITD_XACT_IOC) {
+                ehci_record_interrupt(ehci, USBSTS_INT);
+            }
             itd->transact[i] &= ~ITD_XACT_ACTIVE;
         }
     }
-- 
1.7.7.6