diff --git a/hw/usb-msd.c b/hw/usb-msd.c
index c3a197a..7a08358 100644
--- a/hw/usb-msd.c
+++ b/hw/usb-msd.c
@@ -315,9 +315,9 @@ static int usb_msd_handle_control(USBDevice *dev, USBPacket *p,
     return ret;
 }
 
-static void usb_msd_cancel_io(USBPacket *p, void *opaque)
+static void usb_msd_cancel_io(USBDevice *dev, USBPacket *p)
 {
-    MSDState *s = opaque;
+    MSDState *s = DO_UPCAST(MSDState, dev, dev);
     s->scsi_dev->info->cancel_io(s->scsi_dev, s->tag);
     s->packet = NULL;
     s->scsi_len = 0;
@@ -398,7 +398,6 @@ static int usb_msd_handle_data(USBDevice *dev, USBPacket *p)
             }
             if (s->usb_len) {
                 DPRINTF("Deferring packet %p\n", p);
-                usb_defer_packet(p, usb_msd_cancel_io, s);
                 s->packet = p;
                 ret = USB_RET_ASYNC;
             } else {
@@ -421,7 +420,6 @@ static int usb_msd_handle_data(USBDevice *dev, USBPacket *p)
             if (s->data_len != 0 || len < 13)
                 goto fail;
             /* Waiting for SCSI write to complete.  */
-            usb_defer_packet(p, usb_msd_cancel_io, s);
             s->packet = p;
             ret = USB_RET_ASYNC;
             break;
@@ -455,7 +453,6 @@ static int usb_msd_handle_data(USBDevice *dev, USBPacket *p)
             }
             if (s->usb_len) {
                 DPRINTF("Deferring packet %p\n", p);
-                usb_defer_packet(p, usb_msd_cancel_io, s);
                 s->packet = p;
                 ret = USB_RET_ASYNC;
             } else {
@@ -604,6 +601,7 @@ static struct USBDeviceInfo msd_info = {
     .usb_desc       = &desc,
     .init           = usb_msd_initfn,
     .handle_packet  = usb_generic_handle_packet,
+    .cancel_packet  = usb_msd_cancel_io,
     .handle_attach  = usb_desc_attach,
     .handle_reset   = usb_msd_handle_reset,
     .handle_control = usb_msd_handle_control,
diff --git a/hw/usb.c b/hw/usb.c
index 8a9a7fc..4a39cbc 100644
--- a/hw/usb.c
+++ b/hw/usb.c
@@ -345,6 +345,6 @@ void usb_packet_complete(USBDevice *dev, USBPacket *p)
 void usb_cancel_packet(USBPacket * p)
 {
     assert(p->owner != NULL);
-    p->cancel_cb(p, p->cancel_opaque);
+    p->owner->info->cancel_packet(p->owner, p);
     p->owner = NULL;
 }
diff --git a/hw/usb.h b/hw/usb.h
index 80e8e90..9882400 100644
--- a/hw/usb.h
+++ b/hw/usb.h
@@ -194,6 +194,11 @@ struct USBDeviceInfo {
     int (*handle_packet)(USBDevice *dev, USBPacket *p);
 
     /*
+     * Called when a packet is canceled.
+     */
+    void (*cancel_packet)(USBDevice *dev, USBPacket *p);
+
+    /*
      * Called when device is destroyed.
      */
     void (*handle_destroy)(USBDevice *dev);
@@ -263,24 +268,12 @@ struct USBPacket {
     int len;
     /* Internal use by the USB layer.  */
     USBDevice *owner;
-    USBCallback *cancel_cb;
-    void *cancel_opaque;
 };
 
 int usb_handle_packet(USBDevice *dev, USBPacket *p);
 void usb_packet_complete(USBDevice *dev, USBPacket *p);
 void usb_cancel_packet(USBPacket * p);
 
-/* Defer completion of a USB packet.  The hadle_packet routine should then
-   return USB_RET_ASYNC.  Packets that complete immediately (before
-   handle_packet returns) should not call this method.  */
-static inline void usb_defer_packet(USBPacket *p, USBCallback *cancel,
-                                    void * opaque)
-{
-    p->cancel_cb = cancel;
-    p->cancel_opaque = opaque;
-}
-
 void usb_attach(USBPort *port, USBDevice *dev);
 void usb_wakeup(USBDevice *dev);
 int usb_generic_handle_packet(USBDevice *s, USBPacket *p);
diff --git a/usb-linux.c b/usb-linux.c
index 5547b02..f9f8d28 100644
--- a/usb-linux.c
+++ b/usb-linux.c
@@ -335,9 +335,9 @@ static void async_complete(void *opaque)
     }
 }
 
-static void async_cancel(USBPacket *p, void *opaque)
+static void usb_host_async_cancel(USBDevice *dev, USBPacket *p)
 {
-    USBHostDevice *s = opaque;
+    USBHostDevice *s = DO_UPCAST(USBHostDevice, dev, dev);
     AsyncURB *aurb;
 
     QLIST_FOREACH(aurb, &s->aurbs, next) {
@@ -736,7 +736,6 @@ static int usb_host_handle_data(USBDevice *dev, USBPacket *p)
         }
     }
 
-    usb_defer_packet(p, async_cancel, s);
     return USB_RET_ASYNC;
 }
 
@@ -868,7 +867,6 @@ static int usb_host_handle_control(USBDevice *dev, USBPacket *p,
         }
     }
 
-    usb_defer_packet(p, async_cancel, s);
     return USB_RET_ASYNC;
 }
 
@@ -1197,6 +1195,7 @@ static struct USBDeviceInfo usb_host_dev_info = {
     .qdev.size      = sizeof(USBHostDevice),
     .init           = usb_host_initfn,
     .handle_packet  = usb_generic_handle_packet,
+    .cancel_packet  = usb_host_async_cancel,
     .handle_data    = usb_host_handle_data,
     .handle_control = usb_host_handle_control,
     .handle_reset   = usb_host_handle_reset,
