| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.14 59/98] usb: dwc3: gadget: Fix TRB preparation during SG | Date | Sun, 25 Jan 2015 10:07:17 -0800 |
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3.14-stable review patch. If anyone has any objections, please let me know.
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From: Amit Virdi <amit.virdi@st.com>
commit ec512fb8e5611fed1df2895f90317ce6797d6b32 upstream.
When scatter gather (SG) is used, multiple TRBs are prepared from one DWC3 request (dwc3_request). So while preparing TRBs, the 'last' flag should be set only when it is the last TRB being prepared from the last dwc3_request entry.
The current implementation uses list_is_last to check if the dwc3_request is the last entry from the request_list. However, list_is_last returns false for the last entry too. This is because, while preparing the first TRB from a request, the function dwc3_prepare_one_trb modifies the request's next and prev pointers while moving the URB to req_queued. Hence, list_is_last always returns false no matter what.
The correct way is not to access the modified pointers of dwc3_request but to use list_empty macro instead.
Fixes: e5ba5ec833aa (usb: dwc3: gadget: fix scatter gather implementation) Signed-off-by: Amit Virdi <amit.virdi@st.com> Signed-off-by: Felipe Balbi <balbi@ti.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/usb/dwc3/gadget.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
--- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -887,8 +887,7 @@ static void dwc3_prepare_trbs(struct dwc if (i == (request->num_mapped_sgs - 1) || sg_is_last(s)) { - if (list_is_last(&req->list, - &dep->request_list)) + if (list_empty(&dep->request_list)) last_one = true; chain = false; }
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