Re: USB gadgets with configfs hang reboot

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

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.

Ivo
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