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

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Message-ID: <alpine.DEB.2.22.394.2212091349310.3532114@eliteleevi.tm.intel.com>
Date:   Fri, 9 Dec 2022 13:53:31 +0200 (EET)
From:   Kai Vehmanen <kai.vehmanen@...ux.intel.com>
To:     Ricardo Ribalda <ribalda@...omium.org>
cc:     Oliver Neukum <oneukum@...e.com>, Juergen Gross <jgross@...e.com>,
        Mark Brown <broonie@...nel.org>,
        Chromeos Kdump <chromeos-kdump@...gle.com>,
        Daniel Baluta <daniel.baluta@....com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Len Brown <len.brown@...el.com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Nicholas Piggin <npiggin@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Eric Biederman <ebiederm@...ssion.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Joel Fernandes <joel@...lfernandes.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Peter Ujfalusi <peter.ujfalusi@...ux.intel.com>,
        Pavel Machek <pavel@....cz>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Kai Vehmanen <kai.vehmanen@...ux.intel.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Ingo Molnar <mingo@...hat.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Dexuan Cui <decui@...rosoft.com>,
        Takashi Iwai <tiwai@...e.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Bard Liao <yung-chuan.liao@...ux.intel.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>, x86@...nel.org,
        kexec@...ts.infradead.org,
        Alsa-devel <alsa-devel@...a-project.org>, stable@...r.kernel.org,
        sound-open-firmware@...a-project.org,
        linuxppc-dev@...ts.ozlabs.org, linux-hyperv@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
        xen-devel@...ts.xenproject.org
Subject: Re: [PATCH v8 3/3] ASoC: SOF: Fix deadlock when shutdown a frozen
 userspace

Hi,

On Thu, 1 Dec 2022, Ricardo Ribalda wrote:

> On Thu, 1 Dec 2022 at 14:22, 'Oliver Neukum' via Chromeos Kdump <chromeos-kdump@...gle.com> wrote:
> >
> > On 01.12.22 14:03, Ricardo Ribalda wrote:
> > > 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.

I've posted an alternative to ALSA list that reverts the problematic
patch and fixes the problem (the patch was originally addressing)
in a different way:

https://mailman.alsa-project.org/pipermail/alsa-devel/2022-December/209776.html

No changes outside sound/soc/ are needed with this approach.

Br, Kai