From: Ricardo Ribalda <ribalda@chromium.org>
To: Oliver Neukum <oneukum@suse.com>
Cc: Juergen Gross <jgross@suse.com>, Mark Brown <broonie@kernel.org>,
Chromeos Kdump <chromeos-kdump@google.com>,
Daniel Baluta <daniel.baluta@nxp.com>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
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Ranjani Sridharan <ranjani.sridharan@linux.intel.com>,
"Rafael J. Wysocki" <rafael@kernel.org>,
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xen-devel@lists.xenproject.org
Subject: Re: [PATCH v8 3/3] ASoC: SOF: Fix deadlock when shutdown a frozen userspace
Date: Thu, 1 Dec 2022 14:34:16 +0100 [thread overview]
Message-ID: <CANiDSCtm7dCst_atiWk=ZcK_D3=VzvD0+kWXVQr4gEn--JjGkw@mail.gmail.com> (raw)
In-Reply-To: <d3730d1d-6f92-700a-06c4-0e0a35e270b0@suse.com>
Hi Oliver
On Thu, 1 Dec 2022 at 14:22, 'Oliver Neukum' via Chromeos Kdump
<chromeos-kdump@google.com> 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
>
>
>
> --
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> 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
next prev parent reply other threads:[~2022-12-01 13:34 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-01 11:08 [PATCH v8 0/3] ASoC: SOF: Fix deadlock when shutdown a frozen userspace Ricardo Ribalda
2022-12-01 11:08 ` [PATCH v8 1/3] kexec: Refactor kexec_in_progress into a function Ricardo Ribalda
2022-12-01 11:08 ` [PATCH v8 2/3] freezer: refactor pm_freezing " Ricardo Ribalda
2022-12-02 17:47 ` Rafael J. Wysocki
2022-12-05 12:05 ` Ricardo Ribalda
2022-12-01 11:08 ` [PATCH v8 3/3] ASoC: SOF: Fix deadlock when shutdown a frozen userspace Ricardo Ribalda
2022-12-01 12:28 ` Oliver Neukum
2022-12-01 13:03 ` Ricardo Ribalda
2022-12-01 13:22 ` Oliver Neukum
2022-12-01 13:34 ` Ricardo Ribalda [this message]
2022-12-09 11:53 ` Kai Vehmanen
2022-12-01 13:38 ` Takashi Iwai
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