Re: USB gadgets with configfs hang reboot

[Ivaylo Dimitrov <ivo.g.dimitrov.75-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Hi,

On 18.04.2016 10:55, Felipe Balbi wrote:
>
> Hi,
>
> Ivaylo Dimitrov <ivo.g.dimitrov.75-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> writes:
>> Hi,
>>
>> On 16.01.2016 12:40, Ivaylo Dimitrov wrote:
>>> Hi,
>>>
>>> On 16.01.2016 00:48, Tony Lindgren wrote:
>>>> Hi all,
>>>>
>>>> Looks like there's some issue with the USB gadgets and configfs.
>>>>
>>>> I'm seeing rmmod of the UDC driver cause a warning and then reboot
>>>> hangs the system. This happens at least with v4.4, and I've reproduced
>>>> it with dwc3 and musb so it seems to be generic.
>>>>
>>>
>>> Having configfs is not needed, disabling usb gadgets (#
>>> CONFIG_USB_MUSB_GADGET is not set) seems to solved at least poweroff
>>> hang issue on N900. Also, g_nokia is not a module in the config I use,
>>> so I guess the problem is not related whether gadgets are modular or
>>> not. Unfortunately I was not able to test reboot, as rootfs became
>>> corrupted after the first poweroff :( . So it looks like my theory that
>>> onenand corruption on N900 is because poweroff/reboot hangs is wrong.
>>
>> (copied from "Re: [PATCH] usb: f_mass_storage: test whether thread is
>> running before starting another" thread)
>>
>> Yet another problem with USB gadget, this time with f_acm - if there is
>> an open /dev/ttyGSn device, it is impossible to reboot/power down the
>> device.
>>
>> My investigation shown that there is a process(pnatd) that opens
>> /dev/ttyGSn devices, so gserial_free_port() hangs on
>> wait_event(port->close_wait, gs_closed(port)); if I do "cd
>> /sys/bus/platform/drivers/musb-hdrc && echo musb-hdrc.0.auto > unbind".
>>
>> Unfortunately I don't have serial debug port connector on my N900, so I
>> can't capture logs after the reboot command, however, I suspect it hangs
>> on the same place as with unbind.
>>
>> That looks weird, as one would expect that close() is called when the
>> kernel kills user processes on reboot/powerdown.
>
> right, care to enable lockup detection and see if you can get more info
> out of it ?
>

Nothing interesting, besides that screen does not work :(. However, the 
device boots, I can connect through wifi and reboot still hangs. Also, I 
don't see that port->close_wait in /proc/lockdep. Is that expected?

Is there a reason why a process (pnatd in this particular case) doesn't 
get killed on reboot?

Ivo
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