usb: dwc3: gadget: Reset num TRBs before giving back the request

Consider a scenario where cable disconnect happens when there is an active
usb reqest queued to the UDC. As part of the disconnect we would issue an
end transfer with no interrupt-on-completion before giving back this
request. Since we are giving back the request without skipping TRBs the
num_trbs field of dwc3_request still holds the stale value previously used.
Function drivers re-use same request for a given bind-unbind session and
hence their dwc3_request context gets preserved across cable
disconnect/connect. When such a request gets re-queued after cable connect,
we would increase the num_trbs field on top of the previous stale value
thus incorrectly representing the number of TRBs used. Fix this by
resetting num_trbs field before giving back the request.

Fixes: 09fe1f8 ("usb: dwc3: gadget: track number of TRBs per request")
Cc: stable <stable@kernel.org>
Signed-off-by: Elson Roy Serrao <quic_eserrao@quicinc.com>
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Message-ID: <1685654850-8468-1-git-send-email-quic_eserrao@quicinc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Elson Roy Serrao

drivers/usb/dwc3/gadget.c

@@ -198,6 +198,7 @@ static void dwc3_gadget_del_and_unmap_request(struct dwc3_ep *dep,
 	list_del(&req->list);
 	req->remaining = 0;
 	req->needs_extra_trb = false;
+	req->num_trbs = 0;
 
 	if (req->request.status == -EINPROGRESS)
 		req->request.status = status;