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ALSA: control: Keep the previous numid at snd_ctl_rename_id()

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We don't need to change the numid at each time snd_ctl_rename_id() is
called, as the control element size itself doesn't change.  Let's keep
the previous numid value.

Along with it, add a note about calling this function only in the
card init phase.

Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20230606094035.14808-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2023-06-06 11:40:35 +02:00
parent ebcbfd8463
commit 306f3f78a5
1 changed files with 10 additions and 2 deletions
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12
sound/core/control.c
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@ -730,12 +730,20 @@ EXPORT_SYMBOL_GPL(snd_ctl_activate_id);
* Finds the control with the old id from the card, and replaces the
* id with the new one.
*
* The function tries to keep the already assigned numid while replacing
* the rest.
*
* Note that this function should be used only in the card initialization
* phase. Calling after the card instantiation may cause issues with
* user-space expecting persistent numids.
*
* Return: Zero if successful, or a negative error code on failure.
*/
int snd_ctl_rename_id(struct snd_card *card, struct snd_ctl_elem_id *src_id,
struct snd_ctl_elem_id *dst_id)
{
struct snd_kcontrol *kctl;
int saved_numid;
down_write(&card->controls_rwsem);
kctl = snd_ctl_find_id(card, src_id);
@ -743,10 +751,10 @@ int snd_ctl_rename_id(struct snd_card *card, struct snd_ctl_elem_id *src_id,
up_write(&card->controls_rwsem);
return -ENOENT;
}
saved_numid = kctl->id.numid;
remove_hash_entries(card, kctl);
kctl->id = *dst_id;
kctl->id.numid = card->last_numid + 1;
card->last_numid += kctl->count;
kctl->id.numid = saved_numid;
add_hash_entries(card, kctl);
up_write(&card->controls_rwsem);
return 0;