Re: [PATCH v4] ALSA: core: Fix deadlock when shutdown a frozen userspace

[Takashi Iwai <tiwai@suse.de>]

On Mon, 28 Nov 2022 14:42:49 +0100,
Ricardo Ribalda wrote:
> 
> During kexec(), the userspace is frozen. Therefore we cannot wait for it
> to complete.
> 
> Avoid running snd_sof_machine_unregister during shutdown.
> 
> This fixes:
> 
> [   84.943749] Freezing user space processes ... (elapsed 0.111 seconds) done.
> [  246.784446] INFO: task kexec-lite:5123 blocked for more than 122 seconds.
> [  246.819035] Call Trace:
> [  246.821782]  <TASK>
> [  246.824186]  __schedule+0x5f9/0x1263
> [  246.828231]  schedule+0x87/0xc5
> [  246.831779]  snd_card_disconnect_sync+0xb5/0x127
> ...
> [  246.889249]  snd_sof_device_shutdown+0xb4/0x150
> [  246.899317]  pci_device_shutdown+0x37/0x61
> [  246.903990]  device_shutdown+0x14c/0x1d6
> [  246.908391]  kernel_kexec+0x45/0xb9
> 
> And:
> 
> [  246.893222] INFO: task kexec-lite:4891 blocked for more than 122 seconds.
> [  246.927709] Call Trace:
> [  246.930461]  <TASK>
> [  246.932819]  __schedule+0x5f9/0x1263
> [  246.936855]  ? fsnotify_grab_connector+0x5c/0x70
> [  246.942045]  schedule+0x87/0xc5
> [  246.945567]  schedule_timeout+0x49/0xf3
> [  246.949877]  wait_for_completion+0x86/0xe8
> [  246.954463]  snd_card_free+0x68/0x89
> ...
> [  247.001080]  platform_device_unregister+0x12/0x35
> 
> Cc: stable@vger.kernel.org
> Fixes: 83bfc7e793b5 ("ASoC: SOF: core: unregister clients and machine drivers in .shutdown")
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
> To: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
> To: Liam Girdwood <lgirdwood@gmail.com>
> To: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
> To: Bard Liao <yung-chuan.liao@linux.intel.com>
> To: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
> To: Kai Vehmanen <kai.vehmanen@linux.intel.com>
> To: Daniel Baluta <daniel.baluta@nxp.com>
> To: Mark Brown <broonie@kernel.org>
> To: Jaroslav Kysela <perex@perex.cz>
> To: Takashi Iwai <tiwai@suse.com>
> Cc: sound-open-firmware@alsa-project.org
> Cc: alsa-devel@alsa-project.org
> Cc: linux-kernel@vger.kernel.org
> ---
> Changes in v4:
> - Do not call snd_sof_machine_unregister from shutdown.
> - Link to v3: https://lore.kernel.org/r/20221127-snd-freeze-v3-0-a2eda731ca14@chromium.org

The subject prefix should be adjusted -- now it's no longer about ALSA
core but specific to ASoC SOF.


thanks,

Takashi