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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Thinh Nguyen <thinhn@synopsys.com>,
        Felipe Balbi <balbi@kernel.org>
Subject: [PATCH 4.19 36/54] usb: dwc3: gadget: Wrap around when skip TRBs
Date:   Sat, 11 Apr 2020 14:09:18 +0200
Message-Id: <20200411115512.087843119@linuxfoundation.org>
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From: Thinh Nguyen <Thinh.Nguyen@synopsys.com>

commit 2dedea035ae82c5af0595637a6eda4655532b21e upstream.

When skipping TRBs, we need to account for wrapping around the ring
buffer and not modifying some invalid TRBs. Without this fix, dwc3 won't
be able to check for available TRBs.

Cc: stable <stable@vger.kernel.org>
Fixes: 7746a8dfb3f9 ("usb: dwc3: gadget: extract dwc3_gadget_ep_skip_trbs()")
Signed-off-by: Thinh Nguyen <thinhn@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/dwc3/gadget.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1369,7 +1369,7 @@ static void dwc3_gadget_ep_skip_trbs(str
 	for (i = 0; i < req->num_trbs; i++) {
 		struct dwc3_trb *trb;
 
-		trb = req->trb + i;
+		trb = &dep->trb_pool[dep->trb_dequeue];
 		trb->ctrl &= ~DWC3_TRB_CTRL_HWO;
 		dwc3_ep_inc_deq(dep);
 	}