Re: USB gadgets with configfs hang reboot

[Felipe Balbi <balbi-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

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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 ?

-- 
balbi

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