[PATCH 6.6 056/143] ASoC: soc-card: Fix missing locking in snd_soc_card_get_kcontrol()

Greg Kroah-Hartman
2024-03-04T21:38:22Z

From: Richard Fitzgerald <rf@opensource.cirrus.com>

[ Upstream commit eba2eb2495f47690400331c722868902784e59de ]

snd_soc_card_get_kcontrol() must be holding a read lock on
card->controls_rwsem while walking the controls list.

Compare with snd_ctl_find_numid().

The existing function is renamed snd_soc_card_get_kcontrol_locked()
so that it can be called from contexts that are already holding
card->controls_rwsem (for example, control get/put functions).

There are few direct or indirect callers of
snd_soc_card_get_kcontrol(), and most are safe. Three require
changes, which have been included in this patch:

codecs/cs35l45.c:
cs35l45_activate_ctl() is called from a control put() function so
is changed to call snd_soc_card_get_kcontrol_locked().

codecs/cs35l56.c:
cs35l56_sync_asp1_mixer_widgets_with_firmware() is called from
control get()/put() functions so is changed to call
snd_soc_card_get_kcontrol_locked().

fsl/fsl_xcvr.c:
fsl_xcvr_activate_ctl() is called from three places, one of which
already holds card->controls_rwsem:
1. fsl_xcvr_mode_put(), a control put function, which will
already be holding card->controls_rwsem.
2. fsl_xcvr_startup(), a DAI startup function.
3. fsl_xcvr_shutdown(), a DAI shutdown function.

To fix this, fsl_xcvr_activate_ctl() has been changed to call
snd_soc_card_get_kcontrol_locked() so that it is safe to call
directly from fsl_xcvr_mode_put().
The fsl_xcvr_startup() and fsl_xcvr_shutdown() functions have been
changed to take a read lock on card->controls_rsem() around calls
to fsl_xcvr_activate_ctl(). While this is not very elegant, it
keeps the change small, to avoid this patch creating a large
collateral churn in fsl/fsl_xcvr.c.

Analysis of other callers of snd_soc_card_get_kcontrol() is that
they do not need any changes, they are not holding card->controls_rwsem
when they call snd_soc_card_get_kcontrol().

Direct callers of snd_soc_card_get_kcontrol():
fsl/fsl_spdif.c: fsl_spdif_dai_probe() - DAI probe function
fsl/fsl_micfil.c: voice_detected_fn() - IRQ handler

Indirect callers via soc_component_notify_control():
codecs/cs42l43: cs42l43_mic_shutter() - IRQ handler
codecs/cs42l43: cs42l43_spk_shutter() - IRQ handler
codecs/ak4118.c: ak4118_irq_handler() - IRQ handler
codecs/wm_adsp.c: wm_adsp_write_ctl() - not currently used

Indirect callers via snd_soc_limit_volume():
qcom/sc8280xp.c: sc8280xp_snd_init() - DAIlink init function
ti/rx51.c: rx51_aic34_init() - DAI init function

I don't have hardware to test the fsl/*, qcom/sc828xp.c, ti/rx51.c
and ak4118.c changes.

Backport note:
The fsl/, qcom/, cs35l45, cs35l56 and cs42l43 callers were added
since the Fixes commit so won't all be present on older kernels.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Fixes: 209c6cdfd283 ("ASoC: soc-card: move snd_soc_card_get_kcontrol() to soc-card")
Link: https://lore.kernel.org/r/20240221123710.690224-1-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/sound/soc-card.h | 2 ++
sound/soc/codecs/cs35l56.c | 2 +-
sound/soc/fsl/fsl_xcvr.c | 12 +++++++++++-
sound/soc/soc-card.c | 24 ++++++++++++++++++++++--
4 files changed, 36 insertions(+), 4 deletions(-)

diff --git a/include/sound/soc-card.h b/include/sound/soc-card.h
index ecc02e955279f..1f4c39922d825 100644
--- a/include/sound/soc-card.h
+++ b/include/sound/soc-card.h
@@ -30,6 +30,8 @@ static inline void snd_soc_card_mutex_unlock(struct snd_soc_card *card)

struct snd_kcontrol *snd_soc_card_get_kcontrol(struct snd_soc_card *soc_card,
const char *name);
+struct snd_kcontrol *snd_soc_card_get_kcontrol_locked(struct snd_soc_card *soc_card,
+ const char *name);
int snd_soc_card_jack_new(struct snd_soc_card *card, const char *id, int type,
struct snd_soc_jack *jack);
int snd_soc_card_jack_new_pins(struct snd_soc_card *card, const char *id,
diff --git a/sound/soc/codecs/cs35l56.c b/sound/soc/codecs/cs35l56.c
index 83178d7c1197b..161f599ecbaee 100644
--- a/sound/soc/codecs/cs35l56.c
+++ b/sound/soc/codecs/cs35l56.c
@@ -112,7 +112,7 @@ static int cs35l56_sync_asp1_mixer_widgets_with_firmware(struct cs35l56_private
name = full_name;
}

- kcontrol = snd_soc_card_get_kcontrol(dapm->card, name);
+ kcontrol = snd_soc_card_get_kcontrol_locked(dapm->card, name);
if (!kcontrol) {
dev_warn(cs35l56->base.dev, "Could not find control %s\n", name);
continue;
diff --git a/sound/soc/fsl/fsl_xcvr.c b/sound/soc/fsl/fsl_xcvr.c
index f0fb33d719c25..c46f64557a7ff 100644
--- a/sound/soc/fsl/fsl_xcvr.c
+++ b/sound/soc/fsl/fsl_xcvr.c
@@ -174,7 +174,9 @@ static int fsl_xcvr_activate_ctl(struct snd_soc_dai *dai, const char *name,
struct snd_kcontrol *kctl;
bool enabled;

- kctl = snd_soc_card_get_kcontrol(card, name);
+ lockdep_assert_held(&card->snd_card->controls_rwsem);
+
+ kctl = snd_soc_card_get_kcontrol_locked(card, name);
if (kctl == NULL)
return -ENOENT;

@@ -576,10 +578,14 @@ static int fsl_xcvr_startup(struct snd_pcm_substream *substream,
xcvr->streams |= BIT(substream->stream);

if (!xcvr->soc_data->spdif_only) {
+ struct snd_soc_card *card = dai->component->card;
+
/* Disable XCVR controls if there is stream started */
+ down_read(&card->snd_card->controls_rwsem);
fsl_xcvr_activate_ctl(dai, fsl_xcvr_mode_kctl.name, false);
fsl_xcvr_activate_ctl(dai, fsl_xcvr_arc_mode_kctl.name, false);
fsl_xcvr_activate_ctl(dai, fsl_xcvr_earc_capds_kctl.name, false);
+ up_read(&card->snd_card->controls_rwsem);
}

return 0;
@@ -598,11 +604,15 @@ static void fsl_xcvr_shutdown(struct snd_pcm_substream *substream,
/* Enable XCVR controls if there is no stream started */
if (!xcvr->streams) {
if (!xcvr->soc_data->spdif_only) {
+ struct snd_soc_card *card = dai->component->card;
+
+ down_read(&card->snd_card->controls_rwsem);
fsl_xcvr_activate_ctl(dai, fsl_xcvr_mode_kctl.name, true);
fsl_xcvr_activate_ctl(dai, fsl_xcvr_arc_mode_kctl.name,
(xcvr->mode == FSL_XCVR_MODE_ARC));
fsl_xcvr_activate_ctl(dai, fsl_xcvr_earc_capds_kctl.name,
(xcvr->mode == FSL_XCVR_MODE_EARC));
+ up_read(&card->snd_card->controls_rwsem);
}
ret = regmap_update_bits(xcvr->regmap, FSL_XCVR_EXT_IER0,
FSL_XCVR_IRQ_EARC_ALL, 0);
diff --git a/sound/soc/soc-card.c b/sound/soc/soc-card.c
index 285ab4c9c7168..8a2f163da6bc9 100644
--- a/sound/soc/soc-card.c
+++ b/sound/soc/soc-card.c
@@ -5,6 +5,9 @@
// Copyright (C) 2019 Renesas Electronics Corp.
// Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
//
+
+#include <linux/lockdep.h>
+#include <linux/rwsem.h>
#include <sound/soc.h>
#include <sound/jack.h>

@@ -26,12 +29,15 @@ static inline int _soc_card_ret(struct snd_soc_card *card,
return ret;
}

-struct snd_kcontrol *snd_soc_card_get_kcontrol(struct snd_soc_card *soc_card,
- const char *name)
+struct snd_kcontrol *snd_soc_card_get_kcontrol_locked(struct snd_soc_card *soc_card,
+ const char *name)
{
struct snd_card *card = soc_card->snd_card;
struct snd_kcontrol *kctl;

+ /* must be held read or write */
+ lockdep_assert_held(&card->controls_rwsem);
+
if (unlikely(!name))
return NULL;

@@ -40,6 +46,20 @@ struct snd_kcontrol *snd_soc_card_get_kcontrol(struct snd_soc_card *soc_card,
return kctl;
return NULL;
}
+EXPORT_SYMBOL_GPL(snd_soc_card_get_kcontrol_locked);
+
+struct snd_kcontrol *snd_soc_card_get_kcontrol(struct snd_soc_card *soc_card,
+ const char *name)
+{
+ struct snd_card *card = soc_card->snd_card;
+ struct snd_kcontrol *kctl;
+
+ down_read(&card->controls_rwsem);
+ kctl = snd_soc_card_get_kcontrol_locked(soc_card, name);
+ up_read(&card->controls_rwsem);
+
+ return kctl;
+}
EXPORT_SYMBOL_GPL(snd_soc_card_get_kcontrol);

static int jack_new(struct snd_soc_card *card, const char *id, int type,
--
2.43.0