Re: Disconnect race in Gadget core

[Felipe Balbi <balbi@kernel.org>]

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Hi,

Peter Chen <peter.chen@kernel.org> writes:
> On 21-05-16 10:51:51, Alan Stern wrote:
>> On Sun, May 16, 2021 at 12:43:58PM +0300, Felipe Balbi wrote:
>> > 
>> > Hi,
>> > 
>> > Alan Stern <stern@rowland.harvard.edu> writes:
>> > >
>> > > If it's okay to call those functions in interrupt context then the 
>> > > kerneldoc definitely should be updated.  However, I don't see why you 
>> > > would want to make DELAYED_STATUS mandatory.  If all the necessary work 
>> > > can be done in the set_alt handler, why not return the status 
>> > > immediately?
>> > 
>> > because we avoid a special case. Instead of having magic return value to
>> > mean "Don't do anything until I enqueue a request" we can just make that
>> > an assumption, i.e. gadget driver *must* enqueue requests for data and
>> > status stages.
>> 
>> Okay.  But that would require auditing every gadget/function driver to 
>> ensure that they _do_ enqueue status stage requests
>
> CDNS3 UDC doesn't enqueue status stage by SW, instead, SW tells HW to do
> it by setting registers.

That's a peculiarity of this particular UDC. Gadget driver will still
call usb_ep_queue() in some situations.

-- 
balbi

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