Re: [PATCH v8 3/3] ASoC: SOF: Fix deadlock when shutdown a frozen userspace

[Oliver Neukum]

On 01.12.22 14:03, Ricardo Ribalda wrote:

Hi,
 
> This patchset does not modify this behaviour. It simply fixes the
> stall for kexec().
>
> The  patch that introduced the stall:
> 83bfc7e793b5 ("ASoC: SOF: core: unregister clients and machine drivers
> in .shutdown")

That patch is problematic. I would go as far as saying that
it needs to be reverted.

> was sent as a generalised version of:
> https://github.com/thesofproject/linux/pull/3388
>
> AFAIK, we would need a similar patch for every single board.... which
> I am not sure it is doable in a reasonable timeframe.
>
> On the meantime this seems like a decent compromises. Yes, a
> miss-behaving userspace can still stall during suspend, but that was
> not introduced in this patch.

Well, I mean if you know what wrong then I'd say at least return to
a sanely broken state.

The whole approach is wrong. You need to be able to deal with user
space talking to removed devices by returning an error and keeping
the resources association with the open file allocated until
user space calls close()

	Regards
		Oliver