Re: [PATCH 4/6] usb: dwc3: gadget: Give back staled requests

[Felipe Balbi <balbi@kernel.org>]

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Hi,

Thinh Nguyen <Thinh.Nguyen@synopsys.com> writes:
>> Thinh Nguyen <Thinh.Nguyen@synopsys.com> writes:
>>> If a request is dequeued, the transfer is cancelled. Give back all
>>> the started requests.
>>>
>>> In most scenarios, the function driver dequeues all requests of a
>>> transfer when there's a failure. If the function driver follows this,
>>> then it's fine. If not, then we'd be skipping TRBs at different points
>>> within the dequeue and enqueue pointers, making dequeue/enqueue pointers
>>> useless. To enforce and make sure that we're properly skipping TRBs,
>>> cancel all the started requests and give back all the cancelled requests
>>> to the function drivers.
>> Which function driver is *not* cancelling transfers correctly? We can
>> (and should) be defensive on dwc3, but let's not hide bugs on function
>> drivers either.
>>
>
> I didn't review all the function drivers for this. I just see a 
> potential issue and go for a more defensive approach. What's your 
> suggestion?

Fair enough, that's good for my understading of why the patch was
created. Is there a way to add a WARN() or something like that so we
catch erroneous gadget drivers easily? Also, could you check if we need
a documentation update for the gadget API with regards to this finding?

cheers

-- 
balbi

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