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Date:   Mon, 28 Nov 2022 10:26:50 +0100
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Subject: Re: [PATCH v3 0/2] ALSA: core: Fix deadlock when shutdown a frozen
 userspace
To:     Ricardo Ribalda <ribalda@chromium.org>,
        Takashi Iwai <tiwai@suse.com>, Len Brown <len.brown@intel.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
        Kai Vehmanen <kai.vehmanen@linux.intel.com>,
        Ranjani Sridharan <ranjani.sridharan@linux.intel.com>,
        Mark Brown <broonie@kernel.org>,
        Jaroslav Kysela <perex@perex.cz>, Pavel Machek <pavel@ucw.cz>,
        "Rafael J. Wysocki" <rafael@kernel.org>
Cc:     alsa-devel@alsa-project.org,
        "Joel Fernandes (Google)" <joel@joelfernandes.org>,
        linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
References: <20221127-snd-freeze-v3-0-a2eda731ca14@chromium.org>
Content-Language: en-US
From:   Oliver Neukum <oneukum@suse.com>
In-Reply-To: <20221127-snd-freeze-v3-0-a2eda731ca14@chromium.org>
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On 28.11.22 10:10, Ricardo Ribalda wrote:
> Since 83bfc7e793b5 ("ASoC: SOF: core: unregister clients and machine drivers in .shutdown")
> we wait for userspace to close its fds.
> 
> But that will never occur with a frozen userspace (like during kexec()).


Hi,

that means that user space can delay an unplugging process for an
indefinite time. And that is a problem. I am afraid there is a problem
with the basic approach, even outside of times user space is frozen.

	Regards
		Oliver