usb: split packet result into actual_length + status

Since with the ehci and xhci controllers a single packet can be larger
then maxpacketsize, it is possible for the result of a single packet
to be both having transferred some data as well as the transfer to have
an error.

An example would be an input transfer from a bulk endpoint successfully
receiving 1 or more maxpacketsize packets from the device, followed
by a packet signalling halt.

While already touching all the devices and controllers handle_packet /
handle_data / handle_control code, also change the return type of
these functions to void, solely storing the status in the packet. To
make the code paths for regular versus async packet handling more
uniform.

This patch unfortunately is somewhat invasive, since makeing the qemu
usb core deal with this requires changes everywhere. This patch only
prepares the usb core for this, all the hcd / device changes are done
in such a way that there are no functional changes.

This patch has been tested with uhci and ehci hcds, together with usb-audio,
usb-hid and usb-storage devices, as well as with usb-redir redirection
with a wide variety of real devices.

Note that there is usually no need to directly set packet->actual_length
form devices handle_data callback, as that is done by usb_packet_copy()

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

1 files changed, 17 insertions, 21 deletions

diff --git a/hw/usb/dev-wacom.c b/hw/usb/dev-wacom.c
index ed9a5ee358..08b416daa6 100644
--- a/hw/usb/dev-wacom.c
+++ b/hw/usb/dev-wacom.c
@@ -250,7 +250,7 @@ static void usb_wacom_handle_reset(USBDevice *dev)
     s->mode = WACOM_MODE_HID;
 }
 
-static int usb_wacom_handle_control(USBDevice *dev, USBPacket *p,
+static void usb_wacom_handle_control(USBDevice *dev, USBPacket *p,
                int request, int value, int index, int length, uint8_t *data)
 {
     USBWacomState *s = (USBWacomState *) dev;
@@ -258,10 +258,9 @@ static int usb_wacom_handle_control(USBDevice *dev, USBPacket *p,
 
     ret = usb_desc_handle_control(dev, p, request, value, index, length, data);
     if (ret >= 0) {
-        return ret;
+        return;
     }
 
-    ret = 0;
     switch (request) {
     case WACOM_SET_REPORT:
         if (s->mouse_grabbed) {
@@ -269,61 +268,58 @@ static int usb_wacom_handle_control(USBDevice *dev, USBPacket *p,
             s->mouse_grabbed = 0;
         }
         s->mode = data[0];
-        ret = 0;
         break;
     case WACOM_GET_REPORT:
         data[0] = 0;
         data[1] = s->mode;
-        ret = 2;
+        p->actual_length = 2;
         break;
     /* USB HID requests */
     case HID_GET_REPORT:
         if (s->mode == WACOM_MODE_HID)
-            ret = usb_mouse_poll(s, data, length);
+            p->actual_length = usb_mouse_poll(s, data, length);
         else if (s->mode == WACOM_MODE_WACOM)
-            ret = usb_wacom_poll(s, data, length);
+            p->actual_length = usb_wacom_poll(s, data, length);
         break;
     case HID_GET_IDLE:
-        ret = 1;
         data[0] = s->idle;
+        p->actual_length = 1;
         break;
     case HID_SET_IDLE:
         s->idle = (uint8_t) (value >> 8);
-        ret = 0;
         break;
     default:
-        ret = USB_RET_STALL;
+        p->status = USB_RET_STALL;
         break;
     }
-    return ret;
 }
 
-static int usb_wacom_handle_data(USBDevice *dev, USBPacket *p)
+static void usb_wacom_handle_data(USBDevice *dev, USBPacket *p)
 {
     USBWacomState *s = (USBWacomState *) dev;
     uint8_t buf[p->iov.size];
-    int ret = 0;
+    int len = 0;
 
     switch (p->pid) {
     case USB_TOKEN_IN:
         if (p->ep->nr == 1) {
-            if (!(s->changed || s->idle))
-                return USB_RET_NAK;
+            if (!(s->changed || s->idle)) {
+                p->status = USB_RET_NAK;
+                return;
+            }
             s->changed = 0;
             if (s->mode == WACOM_MODE_HID)
-                ret = usb_mouse_poll(s, buf, p->iov.size);
+                len = usb_mouse_poll(s, buf, p->iov.size);
             else if (s->mode == WACOM_MODE_WACOM)
-                ret = usb_wacom_poll(s, buf, p->iov.size);
-            usb_packet_copy(p, buf, ret);
+                len = usb_wacom_poll(s, buf, p->iov.size);
+            usb_packet_copy(p, buf, len);
             break;
         }
         /* Fall through.  */
     case USB_TOKEN_OUT:
     default:
-        ret = USB_RET_STALL;
-        break;
+        p->status = USB_RET_STALL;
     }
-    return ret;
 }
 
 static void usb_wacom_handle_destroy(USBDevice *dev)