Because the fsl_udc_core driver shares one 'status_req' object for the
complete ep0 control transfer, it is not possible to prime the final
STATUS phase immediately after the IN transaction.  E.g. ch9getstatus()
executed:

| req = udc->status_req;
| ...
| list_add_tail(&req->queue, &ep->queue);
| if (ep0_prime_status(udc, EP_DIR_OUT))
|       ....
|       struct fsl_req *req = udc->status_req;
|       list_add_tail(&req->queue, &ep->queue);

which corrupts the ep->queue list by inserting 'status_req' twice.  This
causes a kernel oops e.g. when 'lsusb -v' is executed on the host.

Patch delays the final 'ep0_prime_status(udc, EP_DIR_OUT))' by moving it
into the ep0 completion handler.

Signed-off-by: Enrico Scholz <enrico.sch...@sigma-chemnitz.de>
---
 drivers/usb/gadget/fsl_udc_core.c | 16 +++-------------
 1 file changed, 3 insertions(+), 13 deletions(-)

diff --git a/drivers/usb/gadget/fsl_udc_core.c 
b/drivers/usb/gadget/fsl_udc_core.c
index d7138cc..55c4a61 100644
--- a/drivers/usb/gadget/fsl_udc_core.c
+++ b/drivers/usb/gadget/fsl_udc_core.c
@@ -1294,8 +1294,7 @@ static int ep0_prime_status(struct fsl_udc *udc, int 
direction)
                udc->ep0_dir = USB_DIR_OUT;
 
        ep = &udc->eps[0];
-       if (udc->ep0_state != DATA_STATE_XMIT)
-               udc->ep0_state = WAIT_FOR_OUT_STATUS;
+       udc->ep0_state = WAIT_FOR_OUT_STATUS;
 
        req->ep = ep;
        req->req.length = 0;
@@ -1400,8 +1399,6 @@ static void ch9getstatus(struct fsl_udc *udc, u8 
request_type, u16 value,
 
        list_add_tail(&req->queue, &ep->queue);
        udc->ep0_state = DATA_STATE_XMIT;
-       if (ep0_prime_status(udc, EP_DIR_OUT))
-               ep0stall(udc);
 
        return;
 stall:
@@ -1511,14 +1508,6 @@ static void setup_received_irq(struct fsl_udc *udc,
                spin_lock(&udc->lock);
                udc->ep0_state = (setup->bRequestType & USB_DIR_IN)
                                ?  DATA_STATE_XMIT : DATA_STATE_RECV;
-               /*
-                * If the data stage is IN, send status prime immediately.
-                * See 2.0 Spec chapter 8.5.3.3 for detail.
-                */
-               if (udc->ep0_state == DATA_STATE_XMIT)
-                       if (ep0_prime_status(udc, EP_DIR_OUT))
-                               ep0stall(udc);
-
        } else {
                /* No data phase, IN status from gadget */
                udc->ep0_dir = USB_DIR_IN;
@@ -1548,7 +1537,8 @@ static void ep0_req_complete(struct fsl_udc *udc, struct 
fsl_ep *ep0,
        switch (udc->ep0_state) {
        case DATA_STATE_XMIT:
                /* already primed at setup_received_irq */
-               udc->ep0_state = WAIT_FOR_OUT_STATUS;
+               if (ep0_prime_status(udc, EP_DIR_OUT))
+                       ep0stall(udc);
                break;
        case DATA_STATE_RECV:
                /* send status phase */
-- 
1.7.11.4

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