[PATCH] ASoC: soc-card: Fix missing locking in snd_soc_card_get_kcontrol()
From: Richard Fitzgerald
Date: Wed Feb 21 2024 - 07:37:43 EST
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@xxxxxxxxxxxxxxxxxxxxx>
Fixes: 209c6cdfd283 ("ASoC: soc-card: move snd_soc_card_get_kcontrol() to soc-card")
---
It would be great if people could test the fsl/, qcom/, ti/rx51 and ak4418
drivers.
---
include/sound/soc-card.h | 2 ++
sound/soc/codecs/cs35l45.c | 2 +-
sound/soc/codecs/cs35l56.c | 2 +-
sound/soc/fsl/fsl_xcvr.c | 12 +++++++++++-
sound/soc/soc-card.c | 24 ++++++++++++++++++++++--
5 files changed, 37 insertions(+), 5 deletions(-)
diff --git a/include/sound/soc-card.h b/include/sound/soc-card.h
index ecc02e955279..1f4c39922d82 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/cs35l45.c b/sound/soc/codecs/cs35l45.c
index 44c221745c3b..2392c6effed8 100644
--- a/sound/soc/codecs/cs35l45.c
+++ b/sound/soc/codecs/cs35l45.c
@@ -184,7 +184,7 @@ static int cs35l45_activate_ctl(struct snd_soc_component *component,
else
snprintf(name, SNDRV_CTL_ELEM_ID_NAME_MAXLEN, "%s", ctl_name);
- kcontrol = snd_soc_card_get_kcontrol(component->card, name);
+ kcontrol = snd_soc_card_get_kcontrol_locked(component->card, name);
if (!kcontrol) {
dev_err(component->dev, "Can't find kcontrol %s\n", name);
return -EINVAL;
diff --git a/sound/soc/codecs/cs35l56.c b/sound/soc/codecs/cs35l56.c
index 2c1313e34cce..6dd0319bc843 100644
--- a/sound/soc/codecs/cs35l56.c
+++ b/sound/soc/codecs/cs35l56.c
@@ -114,7 +114,7 @@ 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 f0fb33d719c2..c46f64557a7f 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 285ab4c9c716..8a2f163da6bc 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@xxxxxxxxxxx>
//
+
+#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,
--
2.30.2