Re: [PATCH] usb: dwc3: Do not process request if HWO is set for its TRB

[Felipe Balbi <balbi@kernel.org>]

Hi,

Sriharsha Allenki <sallenki@codeaurora.org> writes:
>>>> what problem you actually found? Preferrably with tracepoint data
>>>> showing the fault.
>>> Test case here involves f_fs driver in AIO mode and we see ~8 TRBs in
>>> the queue with HWO set and UPDATE_XFER done. In the failure case I see
>>> thatas part of processingthe interrupt generated by the core for the
>>> completion of the first TRB, the driver isgoing ahead and giving
>> we shouldn't get completion interrupt for the first TRB, only the
>> last. Care to share tracepoint data?
>
> We have seen the issue only once and we do not have any tracepoint
> data for it. But with the internal logging we have in our downstream code,
> I see a race between dequeue from the function driver, and the giveback
> as part of the completion (XferInProgress).

Which other changes do you have in your downstream code? Could this
problem be caused by some of the changes in your downstream tree?

> A request (say Request-1) is dequeued before we could notify it's
> completion to the gadget driver. Because of this, as part of handling
> the completion event for the Request-1 we gaveback the next
> request(Request-2) in the queue which is yet to be processed by the
> core leading to the mentioned SMMU fault.

I really need to see tracepoint of this happening. Every list
modification happens with locks held.

> Normally, the core should not process the TRBs once a request
> has been dequeued because of the stop_active_transfer as part of
> dequeue, but I see a timeout when issuing the end transfer command
> during dequeue because of which core is still processing the TRBs
> in the queue.

Ok, so that's the real problem. End Transfer times out. Are you fixing
the wrong thing?

Please, collect trace point data with UPSTREAM kernel. You can't report
a bug on a downstream kernel without reproducing it in the upstream;
otherwise we will be running in circles here.

-- 
balbi