ALSA: control: add snd_ctl_rename()

Add a snd_ctl_rename() function that takes care of updating the control
hash entries for callers that already have the relevant struct snd_kcontrol
at hand and hold the control write lock (or simply haven't registered the
card yet).

Fixes: c27e1efb ("ALSA: control: Use xarray for faster lookups")
Cc: stable@vger.kernel.org
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Link: https://lore.kernel.org/r/4170b71117ea81357a4f7eb8410f7cde20836c70.1666296963.git.maciej.szmigiero@oracle.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/control.h

@@ -138,6 +138,7 @@ 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);
 int snd_ctl_rename_id(struct snd_card * card, struct snd_ctl_elem_id *src_id, struct snd_ctl_elem_id *dst_id);
+void snd_ctl_rename(struct snd_card *card, struct snd_kcontrol *kctl, const char *name);
 int snd_ctl_activate_id(struct snd_card *card, struct snd_ctl_elem_id *id, int active);
 struct snd_kcontrol *snd_ctl_find_numid(struct snd_card * card, unsigned int numid);
 struct snd_kcontrol *snd_ctl_find_id(struct snd_card * card, struct snd_ctl_elem_id *id);

sound/core/control.c

@@ -753,6 +753,29 @@ int snd_ctl_rename_id(struct snd_card *card, struct snd_ctl_elem_id *src_id,
 }
 EXPORT_SYMBOL(snd_ctl_rename_id);
 
+/**
+ * snd_ctl_rename - rename the control on the card
+ * @card: the card instance
+ * @kctl: the control to rename
+ * @name: the new name
+ *
+ * Renames the specified control on the card to the new name.
+ *
+ * Make sure to take the control write lock - down_write(&card->controls_rwsem).
+ */
+void snd_ctl_rename(struct snd_card *card, struct snd_kcontrol *kctl,
+		    const char *name)
+{
+	remove_hash_entries(card, kctl);
+
+	if (strscpy(kctl->id.name, name, sizeof(kctl->id.name)) < 0)
+		pr_warn("ALSA: Renamed control new name '%s' truncated to '%s'\n",
+			name, kctl->id.name);
+
+	add_hash_entries(card, kctl);
+}
+EXPORT_SYMBOL(snd_ctl_rename);
+
 #ifndef CONFIG_SND_CTL_FAST_LOOKUP
 static struct snd_kcontrol *
 snd_ctl_find_numid_slow(struct snd_card *card, unsigned int numid)