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From: Mark Brown <broonie@kernel.org>
To: Tzung-Bi Shih <tzungbi@google.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>,
	ALSA development <alsa-devel@alsa-project.org>,
	Dylan Reid <dgreid@google.com>,
	Jimmy Cheng-Yi Chiang <cychiang@google.com>,
	Sylwester Nawrocki <s.nawrocki@samsung.com>,
	Linux Samsung SOC <linux-samsung-soc@vger.kernel.org>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	Takashi Iwai <tiwai@suse.de>
Subject: Re: [alsa-devel] [PATCH v2] ASoC: max98090: save and restore SHDN when changing sensitive registers
Date: Wed, 18 Dec 2019 13:26:20 +0000	[thread overview]
Message-ID: <20191218132620.GE3219@sirena.org.uk> (raw)
In-Reply-To: <CA+Px+wXPa_cwdZUQfCx4jAhhj4Q9b7bNABUGazLKOJ7U5ae-mA@mail.gmail.com>

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On Fri, Dec 13, 2019 at 02:05:32AM +0800, Tzung-Bi Shih wrote:

> I have no enough resources to test and trace the code temporarily.
> But is it possible:
> - snd_card_new( ) succeed in snd_soc_bind_card( ), so that userspace
> can see the control

This feels like snd_card_new() is being overly enthusiastic here, I'd
expect that we might have other problems elsewhere with that.  I'd not
expect userspace to see things until snd_card_register() since between
_new() and that we're in the process of building the card up.  Given
this we *will* need to handle partially constructed cards after all,
unless we change the ALSA core.  Takashi?

> - code in later snd_soc_bind_card( ) decided to defer the probe
> - soc_cleanup_card_resources( ) may forget to clean the control?  (not
> sure about this)

There's going to be a race condition where userspace can see the control
on the partially built card regardless of if it gets cleaned up or not.

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WARNING: multiple messages have this Message-ID (diff)
From: Mark Brown <broonie@kernel.org>
To: Tzung-Bi Shih <tzungbi@google.com>
Cc: ALSA development <alsa-devel@alsa-project.org>,
	Linux Samsung SOC <linux-samsung-soc@vger.kernel.org>,
	Jimmy Cheng-Yi Chiang <cychiang@google.com>,
	Takashi Iwai <tiwai@suse.de>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	Sylwester Nawrocki <s.nawrocki@samsung.com>,
	Dylan Reid <dgreid@google.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>
Subject: Re: [alsa-devel] [PATCH v2] ASoC: max98090: save and restore SHDN when changing sensitive registers
Date: Wed, 18 Dec 2019 13:26:20 +0000	[thread overview]
Message-ID: <20191218132620.GE3219@sirena.org.uk> (raw)
In-Reply-To: <CA+Px+wXPa_cwdZUQfCx4jAhhj4Q9b7bNABUGazLKOJ7U5ae-mA@mail.gmail.com>


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On Fri, Dec 13, 2019 at 02:05:32AM +0800, Tzung-Bi Shih wrote:

> I have no enough resources to test and trace the code temporarily.
> But is it possible:
> - snd_card_new( ) succeed in snd_soc_bind_card( ), so that userspace
> can see the control

This feels like snd_card_new() is being overly enthusiastic here, I'd
expect that we might have other problems elsewhere with that.  I'd not
expect userspace to see things until snd_card_register() since between
_new() and that we're in the process of building the card up.  Given
this we *will* need to handle partially constructed cards after all,
unless we change the ALSA core.  Takashi?

> - code in later snd_soc_bind_card( ) decided to defer the probe
> - soc_cleanup_card_resources( ) may forget to clean the control?  (not
> sure about this)

There's going to be a race condition where userspace can see the control
on the partially built card regardless of if it gets cleaned up or not.

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  parent reply	other threads:[~2019-12-18 13:26 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20191128152110epcas3p2b205b4b55f6d8bfac42fcb8faaade93c@epcas3p2.samsung.com>
2019-11-28 15:19 ` [alsa-devel] [PATCH v2] ASoC: max98090: save and restore SHDN when changing sensitive registers Tzung-Bi Shih
2019-12-09 18:59   ` [alsa-devel] Applied "ASoC: max98090: save and restore SHDN when changing sensitive registers" to the asoc tree Mark Brown
2019-12-12 14:09   ` [alsa-devel] [PATCH v2] ASoC: max98090: save and restore SHDN when changing sensitive registers Marek Szyprowski
2019-12-12 14:09     ` Marek Szyprowski
2019-12-12 16:02     ` Marek Szyprowski
2019-12-12 16:02       ` Marek Szyprowski
2019-12-12 16:48       ` Mark Brown
2019-12-12 16:48         ` Mark Brown
2019-12-12 18:05     ` Tzung-Bi Shih
2019-12-12 18:05       ` Tzung-Bi Shih
2019-12-17 14:18       ` Marek Szyprowski
2019-12-17 14:18         ` Marek Szyprowski
2019-12-18 13:26       ` Mark Brown [this message]
2019-12-18 13:26         ` Mark Brown
2019-12-18 14:48         ` Marek Szyprowski
2019-12-18 14:48           ` Marek Szyprowski
2019-12-18 16:24           ` Mark Brown
2019-12-18 16:24             ` Mark Brown
2019-12-19  8:03             ` Marek Szyprowski
2019-12-19  8:03               ` Marek Szyprowski
2019-12-19 12:37               ` Mark Brown
2019-12-19 12:37                 ` Mark Brown
2019-12-19 12:54                 ` Marek Szyprowski
2019-12-19 12:54                   ` Marek Szyprowski
2019-12-19 13:05                   ` Mark Brown
2019-12-19 13:05                     ` Mark Brown
2019-12-19 13:41                     ` Marek Szyprowski
2019-12-19 13:41                       ` Marek Szyprowski
2019-12-19 19:16                       ` Mark Brown
2019-12-19 19:16                         ` Mark Brown
2019-12-20  8:28                         ` Marek Szyprowski
2019-12-20  8:28                           ` Marek Szyprowski
2019-12-20  9:05                           ` Marek Szyprowski
2019-12-20  9:05                             ` Marek Szyprowski
2019-12-20 12:01                             ` Mark Brown
2019-12-20 12:01                               ` Mark Brown
2020-01-08 11:54                               ` Marek Szyprowski
2020-01-08 11:54                                 ` Marek Szyprowski
2020-01-09 21:18                                 ` Mark Brown
2020-01-09 21:18                                   ` Mark Brown

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