[PATCH 5/8] ALSA: add snd_ctl_add_locked()

[Oswald Buddenhagen <oswald.buddenhagen@gmx.de>]

This is in fact more symmetrical to snd_ctl_remove() than snd_ctl_add()
is - the former could be named snd_ctl_remove_locked() just as well.

This will be used to dynamically change the available controls from
another control's put() callback, which is already locked.

One might want to add snd_ctl_replace_locked() for completeness, but I
have no use for it now.

Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
---
 include/sound/control.h |  1 +
 sound/core/control.c    | 31 +++++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/include/sound/control.h b/include/sound/control.h
index cc3dcc6cfb0f..d4e210831a38 100644
--- a/include/sound/control.h
+++ b/include/sound/control.h
@@ -134,6 +134,7 @@ void snd_ctl_notify_one(struct snd_card * card, unsigned int mask, struct snd_kc
 struct snd_kcontrol *snd_ctl_new1(const struct snd_kcontrol_new * kcontrolnew, void * private_data);
 void snd_ctl_free_one(struct snd_kcontrol * kcontrol);
 int snd_ctl_add(struct snd_card * card, struct snd_kcontrol * kcontrol);
+int snd_ctl_add_locked(struct snd_card * card, struct snd_kcontrol * kcontrol);
 int snd_ctl_remove(struct snd_card * card, struct snd_kcontrol * kcontrol);
 int snd_ctl_replace(struct snd_card *card, struct snd_kcontrol *kcontrol, bool add_on_replace);
 int snd_ctl_remove_id(struct snd_card * card, struct snd_ctl_elem_id *id);
diff --git a/sound/core/control.c b/sound/core/control.c
index 82aa1af1d1d8..ede5ab911add 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -527,6 +527,27 @@ static int snd_ctl_add_replace(struct snd_card *card,
 	return err;
 }
 
+static int snd_ctl_add_replace_locked(struct snd_card *card,
+				      struct snd_kcontrol *kcontrol,
+				      enum snd_ctl_add_mode mode)
+{
+	int err = -EINVAL;
+
+	if (! kcontrol)
+		return err;
+	if (snd_BUG_ON(!card || !kcontrol->info))
+		goto error;
+
+	err = __snd_ctl_add_replace(card, kcontrol, mode);
+	if (err < 0)
+		goto error;
+	return 0;
+
+ error:
+	snd_ctl_free_one(kcontrol);
+	return err;
+}
+
 /**
  * snd_ctl_add - add the control instance to the card
  * @card: the card instance
@@ -547,6 +568,16 @@ int snd_ctl_add(struct snd_card *card, struct snd_kcontrol *kcontrol)
 }
 EXPORT_SYMBOL(snd_ctl_add);
 
+/**
+ * snd_ctl_add_locked - same as snd_ctl_add(), but card->controls_rwsem
+ * is expected to be already locked if necessary.
+ */
+int snd_ctl_add_locked(struct snd_card *card, struct snd_kcontrol *kcontrol)
+{
+	return snd_ctl_add_replace_locked(card, kcontrol, CTL_ADD_EXCLUSIVE);
+}
+EXPORT_SYMBOL(snd_ctl_add_locked);
+
 /**
  * snd_ctl_replace - replace the control instance of the card
  * @card: the card instance
-- 
2.40.0.152.g15d061e6df