usb_core: More legacy control API fixes

In the old API, usb_core_transfer_complete() would ignore
any completions on EP0. The legacy control API will also
ignore most completions on EP0, but it only did so after
filling in the completion event.

If the driver submits a spurious completion on EP0, then
this could clobber a previously queued completion event.

Fix this by deciding whether to ignore the completion
*before* modifying the event data.

Change-Id: I68526898a96efa594ada4e94bb6851aaaf12e92a

1 files changed, 11 insertions, 8 deletions

diff --git a/firmware/usbstack/usb_core.c b/firmware/usbstack/usb_core.c
index 738b92ed4d..8e32e3501f 100644
--- a/firmware/usbstack/usb_core.c
+++ b/firmware/usbstack/usb_core.c
@@ -950,12 +950,8 @@ void usb_core_transfer_complete(int endpoint, int dir, int status, int length)
     struct usb_transfer_completion_event_data* completion_event =
         &ep_data[endpoint].completion_event[EP_DIR(dir)];
 
-    completion_event->endpoint = endpoint;
-    completion_event->dir = dir;
-    completion_event->data[0] = NULL;
-    completion_event->data[1] = NULL;
-    completion_event->status = status;
-    completion_event->length = length;
+    void* data0 = NULL;
+    void* data1 = NULL;
 
 #ifdef USB_LEGACY_CONTROL_API
     if(endpoint == EP_CONTROL) {
@@ -963,14 +959,21 @@ void usb_core_transfer_complete(int endpoint, int dir, int status, int length)
         struct usb_ctrlrequest* req = active_request;
 
         if(dir == USB_DIR_OUT && req && cwdd) {
-            completion_event->data[0] = req;
-            completion_event->data[1] = control_write_data;
+            data0 = req;
+            data1 = control_write_data;
         } else {
             return;
         }
     }
 #endif
 
+    completion_event->endpoint = endpoint;
+    completion_event->dir = dir;
+    completion_event->data[0] = data0;
+    completion_event->data[1] = data1;
+    completion_event->status = status;
+    completion_event->length = length;
+
     usb_signal_transfer_completion(completion_event);
 }