[PATCH] usb: dwc3: Skip TRBs while removing requests in disconnect path

[Elson Roy Serrao]

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 invoking
skip_trbs() in the ep disable path.

Signed-off-by: Elson Roy Serrao <quic_eserrao@xxxxxxxxxxx>
---
 drivers/usb/dwc3/gadget.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 578804d..b45e917 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -986,6 +986,8 @@ static int __dwc3_gadget_ep_enable(struct dwc3_ep *dep, unsigned int action)
 	return 0;
 }
 
+static void dwc3_gadget_ep_skip_trbs(struct dwc3_ep *dep, struct dwc3_request *req);
+
 void dwc3_remove_requests(struct dwc3 *dwc, struct dwc3_ep *dep, int status)
 {
 	struct dwc3_request		*req;
@@ -1000,6 +1002,7 @@ void dwc3_remove_requests(struct dwc3 *dwc, struct dwc3_ep *dep, int status)
 	while (!list_empty(&dep->started_list)) {
 		req = next_request(&dep->started_list);
 
+		dwc3_gadget_ep_skip_trbs(dep, req);
 		dwc3_gadget_giveback(dep, req, status);
 	}
 
@@ -1012,6 +1015,7 @@ void dwc3_remove_requests(struct dwc3 *dwc, struct dwc3_ep *dep, int status)
 	while (!list_empty(&dep->cancelled_list)) {
 		req = next_request(&dep->cancelled_list);
 
+		dwc3_gadget_ep_skip_trbs(dep, req);
 		dwc3_gadget_giveback(dep, req, status);
 	}
 }
-- 
2.7.4