[alsa-devel] snd_usb_usx2y holding onto a lock?

[Takashi Iwai]

On Fri, 17 Aug 2018 09:23:35 +0200,
Joseph Spencer wrote:
> 
> When plugging an audio interface in with nomodeset I see the following in
> the logs:
> 
> Aug 08 23:19:23 localhost.localdomain kernel: INFO: task pulseaudio:1750
> blocked for more than 120 seconds.
> Aug 08 23:19:23 localhost.localdomain kernel:       Tainted: G
>  OE     4.17.11-200.fc28.x86_64+debug #1
> Aug 08 23:19:23 localhost.localdomain kernel: "echo 0 >
> /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> Aug 08 23:19:23 localhost.localdomain kernel: pulseaudio      D12408  1750
>  1268 0x00000000
> Aug 08 23:19:23 localhost.localdomain kernel: Call Trace:
> 
> Aug 08 23:19:23 localhost.localdomain kernel:  ? __schedule+0x2ba/0xaf0
> 
> Aug 08 23:19:23 localhost.localdomain kernel:  ?
> prepare_to_wait_event+0xd2/0x180
> Aug 08 23:19:23 localhost.localdomain kernel:  schedule+0x2f/0x90
> 
> Aug 08 23:19:23 localhost.localdomain kernel:  usX2Y_urbs_start+0x208/0x470
> [snd_usb_usx2y]
> Aug 08 23:19:23 localhost.localdomain kernel:  ? finish_wait+0x80/0x80
(snip) 

So this is waiting for the event to be triggered by the urb
completion, but it didn't happen by some reason on your machine.

> The audio interface doesn't work and without nomodeset X freezes.
> 
> Any help pointing me in the right direction would be greatly appreciated.
> It looks like an issue with the snd_usb_usx2y driver to me, but I'm not
> sure.

Unfortunately the driver is very special and does somewhat magical way
only the author knows of well.
You need to follow the code, and at least check whether the urb
submission at the playback start worked properly as expected.


Takashi