Re: [RFC PATCH] usb: gadget: dfu: Wrap fs operation in workqueue

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hello Jules,

On 29.01.21 11:51, Jules Maselbas wrote:
> Hi Ahmad,
> 
> On Fri, Jan 29, 2021 at 10:51:18AM +0100, Ahmad Fatoum wrote:
>> Hello Jules,
>>
>> On 27.01.21 17:49, Jules Maselbas wrote:
>>> File system operation shouldn't be executed in a poller. Use
>>> a workqueue to delay filesystem operation to command context.
>>>
>>> This is an RFC, extra work must be done to properly handle error
>>> cases and dfu cleanup.
>>
>> I erroneously thought the poller is within the DFU bits. I wonder what
>> side-effect moving the whole USB gadget polling into a workqueue would
>> have. In that case, we wouldn't need to any changes for DFU itself.
>>
> If I understood correctly you're suggesting to wrap the entire dfu
> gadget inside a poller. I have not tried this and it might work.
> However wrapping each fs operation allow the dfu gadget to respond
> to GET_STATUS queries will erase/write operation are on-going.

To allow running in the "background", the UDC calls into the gadget code
in a poller. I was wondering if replacing that poller with a workqueue
would just make the problem go away, not for DFU. It now know it wouldn't:
Work queues work in shell context and doing console stuff in shell context
(via ttyACM gadget) is not a wise choice. So please dismiss my suggestion ^^.

> 
> Jules
> 
> 

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