Hi,
Magnus Lilja <lilja.magnus@xxxxxxxxx> writes:
> Hi
>
> I tried the fsl_udc_core gadget driver on the i.MX31 PDK board and got a
> kernel panic (NULL pointer dereference) when connecting the USB cable. I
> had the g_serial module loaded as well.
>
> The NULL pointer panic comes from gadget/udc/core.c
> usb_gadget_giveback_request() which calls req->complete() and in some
> cases req->complete is NULL.
>
> Commit 304f7e5e1d08 ("usb: gadget: Refactor request completion") changed
> fsl_udc2_core.c (and several other files) and in fsl_udc2_core.c a check
> that req->complete is non-NULL was removed:
>
> --- a/drivers/usb/gadget/udc/fsl_udc_core.c
> +++ b/drivers/usb/gadget/udc/fsl_udc_core.c
> @@ -197,10 +197,8 @@ __acquires(ep->udc->lock)
> ep->stopped = 1;
>
> spin_unlock(&ep->udc->lock);
> - /* complete() is from gadget layer,
> - * eg fsg->bulk_in_complete() */
> - if (req->req.complete)
> - req->req.complete(&ep->ep, &req->req);
> +
> + usb_gadget_giveback_request(&ep->ep, &req->req);
>
> spin_lock(&ep->udc->lock);
> ep->stopped = stopped;
>
> If I re-introduce the check (either in fsl_udc_core.c or core.c) at
> least USB gadget operation using g_serial seems to work just fine.
>
> I don't know the logic in detail to understand whether this is a proper
> fix or if there is some other more problem with the fls_udc_core driver.
> Does anyone have input in this matter?
>
> I can produce a proper patch that fixes this problem by re-introducing
> the check (in either fsl_udc_core.c or core.c) if that is a proper
> solution and I can also assist in testing other fixes to the problem.
->complete() is supposed to be mandatory. Which gadget do you have that
->doesn't set ->complete() to a valid function pointer?
--
balbi
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