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

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi Oliver

On Thu, 1 Dec 2022 at 14:22, 'Oliver Neukum' via Chromeos Kdump
<chromeos-kdump@xxxxxxxxxx> wrote:
>
> 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.
>

It fixes a real issue. We have not had any complaints until we tried
to kexec in the platform.
I wont recommend reverting it until we have an alternative implementation.

kexec is far less common than suspend/reboot.

> > 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()

In general, the whole shutdown is broken for all the subsystems ;).
It is a complicated issue. Users handling fds, devices with DMAs in
the middle of an operation, dma fences....

Unfortunately I am not that familiar with the sound subsystem to make
a proper patch for this.

>
>         Regards
>                 Oliver
>
>
>
> --
> You received this message because you are subscribed to the Google Groups "Chromeos Kdump" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to chromeos-kdump+unsubscribe@xxxxxxxxxx.
> To view this discussion on the web, visit https://groups.google.com/a/google.com/d/msgid/chromeos-kdump/d3730d1d-6f92-700a-06c4-0e0a35e270b0%40suse.com.



-- 
Ricardo Ribalda



[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Security]     [Bugtraq]     [Linux OMAP]     [Linux MIPS]     [ECOS]     [Asterisk Internet PBX]     [Linux API]

  Powered by Linux