* [PATCH] ALSA: jack: Expose injection debugfs at device register phase
@ 2026-10-16 14:06 Takashi Iwai
2026-10-16 15:07 ` Cen Zhang
0 siblings, 1 reply; 2+ messages in thread
From: Takashi Iwai @ 2026-10-16 14:06 UTC (permalink / raw)
To: linux-sound; +Cc: linux-kernel, Cen Zhang
Currently we add debugfs interfaces for jack injection (with
CONFIG_SND_JACK_INJECTION_DEBUG) at creating jack kctls in
snd_jack_kctl_add(). This means that those debugfs interfaces are
already exposed to user-space at the early probe phase -- that is, it
allows user-space already fiddling with it, while other components are
still being initialized and hidden until snd_card_register().
Depending on the driver implementation, such behavior can be an
unpleasant surprise.
For aligning the device exposure behavior, move the debugfs
registration at the device register phase, too. snd_jack_kctl_add()
may still add the corresponding debugfs interfaces (for the
dynamically added jacks, if any), but it's done only conditionally
after the card has been registered.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
include/sound/jack.h | 2 +-
sound/core/jack.c | 56 ++++++++++++++++++++++++++++++++++----------
2 files changed, 45 insertions(+), 13 deletions(-)
diff --git a/include/sound/jack.h b/include/sound/jack.h
index 715b95983188..cf19c333e2eb 100644
--- a/include/sound/jack.h
+++ b/include/sound/jack.h
@@ -62,10 +62,10 @@ struct snd_jack {
struct list_head kctl_list;
struct snd_card *card;
const char *id;
+ bool registered;
#ifdef CONFIG_SND_JACK_INPUT_DEV
struct input_dev *input_dev;
struct mutex input_dev_lock;
- int registered;
int type;
char name[100];
unsigned int key[6]; /* Keep in sync with definitions above */
diff --git a/sound/core/jack.c b/sound/core/jack.c
index d9132b885ea3..a81a64b3bfe7 100644
--- a/sound/core/jack.c
+++ b/sound/core/jack.c
@@ -38,6 +38,7 @@ static const int jack_switch_types[SND_JACK_SWITCH_TYPES] = {
};
#endif /* CONFIG_SND_JACK_INPUT_DEV */
+static void snd_jack_add_debugfs(struct snd_jack *jack);
static void snd_jack_remove_debugfs(struct snd_jack *jack);
static int snd_jack_dev_disconnect(struct snd_device *device)
@@ -88,11 +89,10 @@ static int snd_jack_dev_free(struct snd_device *device)
}
#ifdef CONFIG_SND_JACK_INPUT_DEV
-static int snd_jack_dev_register(struct snd_device *device)
+static int snd_jack_input_dev_register(struct snd_card *card,
+ struct snd_jack *jack)
{
- struct snd_jack *jack = device->device_data;
- struct snd_card *card = device->card;
- int err, i;
+ int i;
snprintf(jack->name, sizeof(jack->name), "%s %s",
card->shortname, jack->id);
@@ -120,14 +120,32 @@ static int snd_jack_dev_register(struct snd_device *device)
input_set_capability(jack->input_dev, EV_KEY, jack->key[i]);
}
- err = input_register_device(jack->input_dev);
- if (err == 0)
- jack->registered = 1;
-
- return err;
+ return input_register_device(jack->input_dev);
+}
+#else
+static inline int snd_jack_input_dev_register(struct snd_card *card,
+ struct snd_jack *jack)
+{
+ return 0;
}
#endif /* CONFIG_SND_JACK_INPUT_DEV */
+static int snd_jack_dev_register(struct snd_device *device)
+{
+ struct snd_card *card = device->card;
+ struct snd_jack *jack = device->device_data;
+ int err;
+
+ err = snd_jack_input_dev_register(card, jack);
+ if (err < 0)
+ return err;
+
+ snd_jack_add_debugfs(jack);
+
+ jack->registered = true;
+ return 0;
+}
+
#ifdef CONFIG_SND_JACK_INJECTION_DEBUG
static void snd_jack_inject_report(struct snd_jack_kctl *jack_kctl, int status)
{
@@ -349,6 +367,9 @@ static int snd_jack_debugfs_add_inject_node(struct snd_jack *jack,
char *tname;
int i;
+ if (jack_kctl->jack_debugfs_root)
+ return 0;
+
/* Don't create injection interface for Phantom jacks */
if (strstr(jack_kctl->kctl->id.name, "Phantom"))
return 0;
@@ -387,6 +408,14 @@ static int snd_jack_debugfs_add_inject_node(struct snd_jack *jack,
return 0;
}
+static void snd_jack_add_debugfs(struct snd_jack *jack)
+{
+ struct snd_jack_kctl *jack_kctl;
+
+ list_for_each_entry(jack_kctl, &jack->kctl_list, list)
+ snd_jack_debugfs_add_inject_node(jack, jack_kctl);
+}
+
static void snd_jack_remove_debugfs(struct snd_jack *jack)
{
struct snd_jack_kctl *jack_kctl;
@@ -403,6 +432,10 @@ static int snd_jack_debugfs_add_inject_node(struct snd_jack *jack,
return 0;
}
+static void snd_jack_add_debugfs(struct snd_jack *jack)
+{
+}
+
static void snd_jack_remove_debugfs(struct snd_jack *jack)
{
}
@@ -423,7 +456,8 @@ static void snd_jack_kctl_add(struct snd_jack *jack, struct snd_jack_kctl *jack_
{
jack_kctl->jack = jack;
list_add_tail(&jack_kctl->list, &jack->kctl_list);
- snd_jack_debugfs_add_inject_node(jack, jack_kctl);
+ if (jack->registered)
+ snd_jack_debugfs_add_inject_node(jack, jack_kctl);
}
static struct snd_jack_kctl * snd_jack_kctl_new(struct snd_card *card, const char *name, unsigned int mask)
@@ -504,9 +538,7 @@ int snd_jack_new(struct snd_card *card, const char *id, int type,
int err;
static const struct snd_device_ops ops = {
.dev_free = snd_jack_dev_free,
-#ifdef CONFIG_SND_JACK_INPUT_DEV
.dev_register = snd_jack_dev_register,
-#endif /* CONFIG_SND_JACK_INPUT_DEV */
.dev_disconnect = snd_jack_dev_disconnect,
};
--
2.55.0
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] ALSA: jack: Expose injection debugfs at device register phase
2026-10-16 14:06 [PATCH] ALSA: jack: Expose injection debugfs at device register phase Takashi Iwai
@ 2026-10-16 15:07 ` Cen Zhang
0 siblings, 0 replies; 2+ messages in thread
From: Cen Zhang @ 2026-10-16 15:07 UTC (permalink / raw)
To: Takashi Iwai; +Cc: linux-sound, linux-kernel
Takashi Iwai <tiwai@suse.de> 于2026年10月16日周五 22:06写道：
>
> Currently we add debugfs interfaces for jack injection (with
> CONFIG_SND_JACK_INJECTION_DEBUG) at creating jack kctls in
> snd_jack_kctl_add(). This means that those debugfs interfaces are
> already exposed to user-space at the early probe phase -- that is, it
> allows user-space already fiddling with it, while other components are
> still being initialized and hidden until snd_card_register().
> Depending on the driver implementation, such behavior can be an
> unpleasant surprise.
>
> For aligning the device exposure behavior, move the debugfs
> registration at the device register phase, too. snd_jack_kctl_add()
> may still add the corresponding debugfs interfaces (for the
> dynamically added jacks, if any), but it's done only conditionally
> after the card has been registered.
>
> Signed-off-by: Takashi Iwai <tiwai@suse.de>
> ---
> include/sound/jack.h | 2 +-
> sound/core/jack.c | 56 ++++++++++++++++++++++++++++++++++----------
> 2 files changed, 45 insertions(+), 13 deletions(-)
>
> diff --git a/include/sound/jack.h b/include/sound/jack.h
> index 715b95983188..cf19c333e2eb 100644
> --- a/include/sound/jack.h
> +++ b/include/sound/jack.h
> @@ -62,10 +62,10 @@ struct snd_jack {
> struct list_head kctl_list;
> struct snd_card *card;
> const char *id;
> + bool registered;
> #ifdef CONFIG_SND_JACK_INPUT_DEV
> struct input_dev *input_dev;
> struct mutex input_dev_lock;
> - int registered;
> int type;
> char name[100];
> unsigned int key[6]; /* Keep in sync with definitions above */
> diff --git a/sound/core/jack.c b/sound/core/jack.c
> index d9132b885ea3..a81a64b3bfe7 100644
> --- a/sound/core/jack.c
> +++ b/sound/core/jack.c
> @@ -38,6 +38,7 @@ static const int jack_switch_types[SND_JACK_SWITCH_TYPES] = {
> };
> #endif /* CONFIG_SND_JACK_INPUT_DEV */
>
> +static void snd_jack_add_debugfs(struct snd_jack *jack);
> static void snd_jack_remove_debugfs(struct snd_jack *jack);
>
> static int snd_jack_dev_disconnect(struct snd_device *device)
> @@ -88,11 +89,10 @@ static int snd_jack_dev_free(struct snd_device *device)
> }
>
> #ifdef CONFIG_SND_JACK_INPUT_DEV
> -static int snd_jack_dev_register(struct snd_device *device)
> +static int snd_jack_input_dev_register(struct snd_card *card,
> + struct snd_jack *jack)
> {
> - struct snd_jack *jack = device->device_data;
> - struct snd_card *card = device->card;
> - int err, i;
> + int i;
>
> snprintf(jack->name, sizeof(jack->name), "%s %s",
> card->shortname, jack->id);
> @@ -120,14 +120,32 @@ static int snd_jack_dev_register(struct snd_device *device)
> input_set_capability(jack->input_dev, EV_KEY, jack->key[i]);
> }
>
> - err = input_register_device(jack->input_dev);
> - if (err == 0)
> - jack->registered = 1;
> -
> - return err;
> + return input_register_device(jack->input_dev);
> +}
> +#else
> +static inline int snd_jack_input_dev_register(struct snd_card *card,
> + struct snd_jack *jack)
> +{
> + return 0;
> }
> #endif /* CONFIG_SND_JACK_INPUT_DEV */
>
> +static int snd_jack_dev_register(struct snd_device *device)
> +{
> + struct snd_card *card = device->card;
> + struct snd_jack *jack = device->device_data;
> + int err;
> +
> + err = snd_jack_input_dev_register(card, jack);
> + if (err < 0)
> + return err;
> +
> + snd_jack_add_debugfs(jack);
> +
> + jack->registered = true;
> + return 0;
> +}
> +
> #ifdef CONFIG_SND_JACK_INJECTION_DEBUG
> static void snd_jack_inject_report(struct snd_jack_kctl *jack_kctl, int status)
> {
> @@ -349,6 +367,9 @@ static int snd_jack_debugfs_add_inject_node(struct snd_jack *jack,
> char *tname;
> int i;
>
> + if (jack_kctl->jack_debugfs_root)
> + return 0;
> +
> /* Don't create injection interface for Phantom jacks */
> if (strstr(jack_kctl->kctl->id.name, "Phantom"))
> return 0;
> @@ -387,6 +408,14 @@ static int snd_jack_debugfs_add_inject_node(struct snd_jack *jack,
> return 0;
> }
>
> +static void snd_jack_add_debugfs(struct snd_jack *jack)
> +{
> + struct snd_jack_kctl *jack_kctl;
> +
> + list_for_each_entry(jack_kctl, &jack->kctl_list, list)
> + snd_jack_debugfs_add_inject_node(jack, jack_kctl);
> +}
> +
> static void snd_jack_remove_debugfs(struct snd_jack *jack)
> {
> struct snd_jack_kctl *jack_kctl;
> @@ -403,6 +432,10 @@ static int snd_jack_debugfs_add_inject_node(struct snd_jack *jack,
> return 0;
> }
>
> +static void snd_jack_add_debugfs(struct snd_jack *jack)
> +{
> +}
> +
> static void snd_jack_remove_debugfs(struct snd_jack *jack)
> {
> }
> @@ -423,7 +456,8 @@ static void snd_jack_kctl_add(struct snd_jack *jack, struct snd_jack_kctl *jack_
> {
> jack_kctl->jack = jack;
> list_add_tail(&jack_kctl->list, &jack->kctl_list);
> - snd_jack_debugfs_add_inject_node(jack, jack_kctl);
> + if (jack->registered)
> + snd_jack_debugfs_add_inject_node(jack, jack_kctl);
> }
>
> static struct snd_jack_kctl * snd_jack_kctl_new(struct snd_card *card, const char *name, unsigned int mask)
> @@ -504,9 +538,7 @@ int snd_jack_new(struct snd_card *card, const char *id, int type,
> int err;
> static const struct snd_device_ops ops = {
> .dev_free = snd_jack_dev_free,
> -#ifdef CONFIG_SND_JACK_INPUT_DEV
> .dev_register = snd_jack_dev_register,
> -#endif /* CONFIG_SND_JACK_INPUT_DEV */
> .dev_disconnect = snd_jack_dev_disconnect,
> };
>
> --
> 2.55.0
>
LGTM.
Reviewed-by: Cen Zhang <zzzccc427@gmail.com>
Best regards,
Cen Zhang
^ permalink raw reply [flat|nested] 2+ messages in thread
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