* [PATCH] ALSA: usb-audio: use kzalloc_flex
@ 2026-03-11 23:27 Rosen Penev
2026-03-12 6:34 ` Takashi Iwai
0 siblings, 1 reply; 5+ messages in thread
From: Rosen Penev @ 2026-03-11 23:27 UTC (permalink / raw)
To: linux-sound; +Cc: Jaroslav Kysela, Takashi Iwai, open list
Saves one allocation by using a flexible array member.
Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
sound/usb/mixer.c | 22 +++++++---------------
sound/usb/mixer.h | 5 +++--
2 files changed, 10 insertions(+), 17 deletions(-)
diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 7007e0c9489b..337815b9e72c 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1393,7 +1393,7 @@ static int mixer_ctl_feature_info(struct snd_kcontrol *kcontrol,
if (!cval->initialized) {
get_min_max_with_quirks(cval, 0, kcontrol);
if (cval->initialized && cval->dBmin >= cval->dBmax) {
- kcontrol->vd[0].access &=
+ kcontrol->vd[0].access &=
~(SNDRV_CTL_ELEM_ACCESS_TLV_READ |
SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK);
snd_ctl_notify(cval->head.mixer->chip->card,
@@ -3006,15 +3006,12 @@ static void snd_usb_mixer_free(struct usb_mixer_interface *mixer)
snd_usb_mixer_disconnect(mixer);
/* Unregister controls first, snd_ctl_remove() frees the element */
- if (mixer->id_elems) {
- for (id = 0; id < MAX_ID_ELEMS; id++) {
- for (list = mixer->id_elems[id]; list; list = next) {
- next = list->next_id_elem;
- if (list->kctl)
- snd_ctl_remove(mixer->chip->card, list->kctl);
- }
+ for (id = 0; id < MAX_ID_ELEMS; id++) {
+ for (list = mixer->id_elems[id]; list; list = next) {
+ next = list->next_id_elem;
+ if (list->kctl)
+ snd_ctl_remove(mixer->chip->card, list->kctl);
}
- kfree(mixer->id_elems);
}
if (mixer->urb) {
kfree(mixer->urb->transfer_buffer);
@@ -3652,16 +3649,11 @@ int snd_usb_create_mixer(struct snd_usb_audio *chip, int ctrlif)
strscpy(chip->card->mixername, "USB Mixer");
- mixer = kzalloc_obj(*mixer);
+ mixer = kzalloc_flex(*mixer, id_elems, MAX_ID_ELEMS);
if (!mixer)
return -ENOMEM;
mixer->chip = chip;
mixer->ignore_ctl_error = !!(chip->quirk_flags & QUIRK_FLAG_IGNORE_CTL_ERROR);
- mixer->id_elems = kzalloc_objs(*mixer->id_elems, MAX_ID_ELEMS);
- if (!mixer->id_elems) {
- kfree(mixer);
- return -ENOMEM;
- }
mixer->hostif = &usb_ifnum_to_if(chip->dev, ctrlif)->altsetting[0];
switch (get_iface_desc(mixer->hostif)->bInterfaceProtocol) {
diff --git a/sound/usb/mixer.h b/sound/usb/mixer.h
index 167fbfcf01ac..30dd30b925fc 100644
--- a/sound/usb/mixer.h
+++ b/sound/usb/mixer.h
@@ -19,8 +19,6 @@ struct usb_mixer_interface {
struct list_head list;
unsigned int ignore_ctl_error;
struct urb *urb;
- /* array[MAX_ID_ELEMS], indexed by unit id */
- struct usb_mixer_elem_list **id_elems;
/* the usb audio specification version this interface complies to */
int protocol;
@@ -42,6 +40,9 @@ struct usb_mixer_interface {
void *private_data;
void (*private_free)(struct usb_mixer_interface *mixer);
void (*private_suspend)(struct usb_mixer_interface *mixer);
+
+ /* array[MAX_ID_ELEMS], indexed by unit id */
+ struct usb_mixer_elem_list *id_elems[];
};
#define MAX_CHANNELS 16 /* max logical channels */
--
2.53.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] ALSA: usb-audio: use kzalloc_flex
2026-03-11 23:27 [PATCH] ALSA: usb-audio: use kzalloc_flex Rosen Penev
@ 2026-03-12 6:34 ` Takashi Iwai
2026-03-12 6:45 ` Rosen Penev
0 siblings, 1 reply; 5+ messages in thread
From: Takashi Iwai @ 2026-03-12 6:34 UTC (permalink / raw)
To: Rosen Penev; +Cc: linux-sound, Jaroslav Kysela, Takashi Iwai, open list
On Thu, 12 Mar 2026 00:27:48 +0100,
Rosen Penev wrote:
>
> Saves one allocation by using a flexible array member.
As it's a fixed size array, it doesn't have to be a flex array at all,
so it can be even simpler.
thanks,
Takashi
>
> Signed-off-by: Rosen Penev <rosenp@gmail.com>
> ---
> sound/usb/mixer.c | 22 +++++++---------------
> sound/usb/mixer.h | 5 +++--
> 2 files changed, 10 insertions(+), 17 deletions(-)
>
> diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
> index 7007e0c9489b..337815b9e72c 100644
> --- a/sound/usb/mixer.c
> +++ b/sound/usb/mixer.c
> @@ -1393,7 +1393,7 @@ static int mixer_ctl_feature_info(struct snd_kcontrol *kcontrol,
> if (!cval->initialized) {
> get_min_max_with_quirks(cval, 0, kcontrol);
> if (cval->initialized && cval->dBmin >= cval->dBmax) {
> - kcontrol->vd[0].access &=
> + kcontrol->vd[0].access &=
> ~(SNDRV_CTL_ELEM_ACCESS_TLV_READ |
> SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK);
> snd_ctl_notify(cval->head.mixer->chip->card,
> @@ -3006,15 +3006,12 @@ static void snd_usb_mixer_free(struct usb_mixer_interface *mixer)
> snd_usb_mixer_disconnect(mixer);
>
> /* Unregister controls first, snd_ctl_remove() frees the element */
> - if (mixer->id_elems) {
> - for (id = 0; id < MAX_ID_ELEMS; id++) {
> - for (list = mixer->id_elems[id]; list; list = next) {
> - next = list->next_id_elem;
> - if (list->kctl)
> - snd_ctl_remove(mixer->chip->card, list->kctl);
> - }
> + for (id = 0; id < MAX_ID_ELEMS; id++) {
> + for (list = mixer->id_elems[id]; list; list = next) {
> + next = list->next_id_elem;
> + if (list->kctl)
> + snd_ctl_remove(mixer->chip->card, list->kctl);
> }
> - kfree(mixer->id_elems);
> }
> if (mixer->urb) {
> kfree(mixer->urb->transfer_buffer);
> @@ -3652,16 +3649,11 @@ int snd_usb_create_mixer(struct snd_usb_audio *chip, int ctrlif)
>
> strscpy(chip->card->mixername, "USB Mixer");
>
> - mixer = kzalloc_obj(*mixer);
> + mixer = kzalloc_flex(*mixer, id_elems, MAX_ID_ELEMS);
> if (!mixer)
> return -ENOMEM;
> mixer->chip = chip;
> mixer->ignore_ctl_error = !!(chip->quirk_flags & QUIRK_FLAG_IGNORE_CTL_ERROR);
> - mixer->id_elems = kzalloc_objs(*mixer->id_elems, MAX_ID_ELEMS);
> - if (!mixer->id_elems) {
> - kfree(mixer);
> - return -ENOMEM;
> - }
>
> mixer->hostif = &usb_ifnum_to_if(chip->dev, ctrlif)->altsetting[0];
> switch (get_iface_desc(mixer->hostif)->bInterfaceProtocol) {
> diff --git a/sound/usb/mixer.h b/sound/usb/mixer.h
> index 167fbfcf01ac..30dd30b925fc 100644
> --- a/sound/usb/mixer.h
> +++ b/sound/usb/mixer.h
> @@ -19,8 +19,6 @@ struct usb_mixer_interface {
> struct list_head list;
> unsigned int ignore_ctl_error;
> struct urb *urb;
> - /* array[MAX_ID_ELEMS], indexed by unit id */
> - struct usb_mixer_elem_list **id_elems;
>
> /* the usb audio specification version this interface complies to */
> int protocol;
> @@ -42,6 +40,9 @@ struct usb_mixer_interface {
> void *private_data;
> void (*private_free)(struct usb_mixer_interface *mixer);
> void (*private_suspend)(struct usb_mixer_interface *mixer);
> +
> + /* array[MAX_ID_ELEMS], indexed by unit id */
> + struct usb_mixer_elem_list *id_elems[];
> };
>
> #define MAX_CHANNELS 16 /* max logical channels */
> --
> 2.53.0
>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] ALSA: usb-audio: use kzalloc_flex
2026-03-12 6:34 ` Takashi Iwai
@ 2026-03-12 6:45 ` Rosen Penev
2026-03-13 22:02 ` Rosen Penev
0 siblings, 1 reply; 5+ messages in thread
From: Rosen Penev @ 2026-03-12 6:45 UTC (permalink / raw)
To: Takashi Iwai; +Cc: linux-sound, Jaroslav Kysela, Takashi Iwai, open list
On Wed, Mar 11, 2026 at 11:34 PM Takashi Iwai <tiwai@suse.de> wrote:
>
> On Thu, 12 Mar 2026 00:27:48 +0100,
> Rosen Penev wrote:
> >
> > Saves one allocation by using a flexible array member.
>
> As it's a fixed size array, it doesn't have to be a flex array at all,
> so it can be even simpler.
That's true. The comment even admits as such. Wonder why it was ever a
pointer allocated with calloc...
>
>
> thanks,
>
> Takashi
>
> >
> > Signed-off-by: Rosen Penev <rosenp@gmail.com>
> > ---
> > sound/usb/mixer.c | 22 +++++++---------------
> > sound/usb/mixer.h | 5 +++--
> > 2 files changed, 10 insertions(+), 17 deletions(-)
> >
> > diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
> > index 7007e0c9489b..337815b9e72c 100644
> > --- a/sound/usb/mixer.c
> > +++ b/sound/usb/mixer.c
> > @@ -1393,7 +1393,7 @@ static int mixer_ctl_feature_info(struct snd_kcontrol *kcontrol,
> > if (!cval->initialized) {
> > get_min_max_with_quirks(cval, 0, kcontrol);
> > if (cval->initialized && cval->dBmin >= cval->dBmax) {
> > - kcontrol->vd[0].access &=
> > + kcontrol->vd[0].access &=
> > ~(SNDRV_CTL_ELEM_ACCESS_TLV_READ |
> > SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK);
> > snd_ctl_notify(cval->head.mixer->chip->card,
> > @@ -3006,15 +3006,12 @@ static void snd_usb_mixer_free(struct usb_mixer_interface *mixer)
> > snd_usb_mixer_disconnect(mixer);
> >
> > /* Unregister controls first, snd_ctl_remove() frees the element */
> > - if (mixer->id_elems) {
> > - for (id = 0; id < MAX_ID_ELEMS; id++) {
> > - for (list = mixer->id_elems[id]; list; list = next) {
> > - next = list->next_id_elem;
> > - if (list->kctl)
> > - snd_ctl_remove(mixer->chip->card, list->kctl);
> > - }
> > + for (id = 0; id < MAX_ID_ELEMS; id++) {
> > + for (list = mixer->id_elems[id]; list; list = next) {
> > + next = list->next_id_elem;
> > + if (list->kctl)
> > + snd_ctl_remove(mixer->chip->card, list->kctl);
> > }
> > - kfree(mixer->id_elems);
> > }
> > if (mixer->urb) {
> > kfree(mixer->urb->transfer_buffer);
> > @@ -3652,16 +3649,11 @@ int snd_usb_create_mixer(struct snd_usb_audio *chip, int ctrlif)
> >
> > strscpy(chip->card->mixername, "USB Mixer");
> >
> > - mixer = kzalloc_obj(*mixer);
> > + mixer = kzalloc_flex(*mixer, id_elems, MAX_ID_ELEMS);
> > if (!mixer)
> > return -ENOMEM;
> > mixer->chip = chip;
> > mixer->ignore_ctl_error = !!(chip->quirk_flags & QUIRK_FLAG_IGNORE_CTL_ERROR);
> > - mixer->id_elems = kzalloc_objs(*mixer->id_elems, MAX_ID_ELEMS);
> > - if (!mixer->id_elems) {
> > - kfree(mixer);
> > - return -ENOMEM;
> > - }
> >
> > mixer->hostif = &usb_ifnum_to_if(chip->dev, ctrlif)->altsetting[0];
> > switch (get_iface_desc(mixer->hostif)->bInterfaceProtocol) {
> > diff --git a/sound/usb/mixer.h b/sound/usb/mixer.h
> > index 167fbfcf01ac..30dd30b925fc 100644
> > --- a/sound/usb/mixer.h
> > +++ b/sound/usb/mixer.h
> > @@ -19,8 +19,6 @@ struct usb_mixer_interface {
> > struct list_head list;
> > unsigned int ignore_ctl_error;
> > struct urb *urb;
> > - /* array[MAX_ID_ELEMS], indexed by unit id */
> > - struct usb_mixer_elem_list **id_elems;
> >
> > /* the usb audio specification version this interface complies to */
> > int protocol;
> > @@ -42,6 +40,9 @@ struct usb_mixer_interface {
> > void *private_data;
> > void (*private_free)(struct usb_mixer_interface *mixer);
> > void (*private_suspend)(struct usb_mixer_interface *mixer);
> > +
> > + /* array[MAX_ID_ELEMS], indexed by unit id */
> > + struct usb_mixer_elem_list *id_elems[];
> > };
> >
> > #define MAX_CHANNELS 16 /* max logical channels */
> > --
> > 2.53.0
> >
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] ALSA: usb-audio: use kzalloc_flex
2026-03-12 6:45 ` Rosen Penev
@ 2026-03-13 22:02 ` Rosen Penev
2026-03-14 13:29 ` Takashi Iwai
0 siblings, 1 reply; 5+ messages in thread
From: Rosen Penev @ 2026-03-13 22:02 UTC (permalink / raw)
To: Takashi Iwai; +Cc: linux-sound, Jaroslav Kysela, Takashi Iwai, open list
On Wed, Mar 11, 2026 at 11:45 PM Rosen Penev <rosenp@gmail.com> wrote:
>
> On Wed, Mar 11, 2026 at 11:34 PM Takashi Iwai <tiwai@suse.de> wrote:
> >
> > On Thu, 12 Mar 2026 00:27:48 +0100,
> > Rosen Penev wrote:
> > >
> > > Saves one allocation by using a flexible array member.
> >
> > As it's a fixed size array, it doesn't have to be a flex array at all,
> > so it can be even simpler.
> That's true. The comment even admits as such. Wonder why it was ever a
> pointer allocated with calloc...
Oh no I see the issue:
sound/usb/mixer.c:#define MAX_ID_ELEMS 256
I don't think this is supposed to be in the header.
> >
> >
> > thanks,
> >
> > Takashi
> >
> > >
> > > Signed-off-by: Rosen Penev <rosenp@gmail.com>
> > > ---
> > > sound/usb/mixer.c | 22 +++++++---------------
> > > sound/usb/mixer.h | 5 +++--
> > > 2 files changed, 10 insertions(+), 17 deletions(-)
> > >
> > > diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
> > > index 7007e0c9489b..337815b9e72c 100644
> > > --- a/sound/usb/mixer.c
> > > +++ b/sound/usb/mixer.c
> > > @@ -1393,7 +1393,7 @@ static int mixer_ctl_feature_info(struct snd_kcontrol *kcontrol,
> > > if (!cval->initialized) {
> > > get_min_max_with_quirks(cval, 0, kcontrol);
> > > if (cval->initialized && cval->dBmin >= cval->dBmax) {
> > > - kcontrol->vd[0].access &=
> > > + kcontrol->vd[0].access &=
> > > ~(SNDRV_CTL_ELEM_ACCESS_TLV_READ |
> > > SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK);
> > > snd_ctl_notify(cval->head.mixer->chip->card,
> > > @@ -3006,15 +3006,12 @@ static void snd_usb_mixer_free(struct usb_mixer_interface *mixer)
> > > snd_usb_mixer_disconnect(mixer);
> > >
> > > /* Unregister controls first, snd_ctl_remove() frees the element */
> > > - if (mixer->id_elems) {
> > > - for (id = 0; id < MAX_ID_ELEMS; id++) {
> > > - for (list = mixer->id_elems[id]; list; list = next) {
> > > - next = list->next_id_elem;
> > > - if (list->kctl)
> > > - snd_ctl_remove(mixer->chip->card, list->kctl);
> > > - }
> > > + for (id = 0; id < MAX_ID_ELEMS; id++) {
> > > + for (list = mixer->id_elems[id]; list; list = next) {
> > > + next = list->next_id_elem;
> > > + if (list->kctl)
> > > + snd_ctl_remove(mixer->chip->card, list->kctl);
> > > }
> > > - kfree(mixer->id_elems);
> > > }
> > > if (mixer->urb) {
> > > kfree(mixer->urb->transfer_buffer);
> > > @@ -3652,16 +3649,11 @@ int snd_usb_create_mixer(struct snd_usb_audio *chip, int ctrlif)
> > >
> > > strscpy(chip->card->mixername, "USB Mixer");
> > >
> > > - mixer = kzalloc_obj(*mixer);
> > > + mixer = kzalloc_flex(*mixer, id_elems, MAX_ID_ELEMS);
> > > if (!mixer)
> > > return -ENOMEM;
> > > mixer->chip = chip;
> > > mixer->ignore_ctl_error = !!(chip->quirk_flags & QUIRK_FLAG_IGNORE_CTL_ERROR);
> > > - mixer->id_elems = kzalloc_objs(*mixer->id_elems, MAX_ID_ELEMS);
> > > - if (!mixer->id_elems) {
> > > - kfree(mixer);
> > > - return -ENOMEM;
> > > - }
> > >
> > > mixer->hostif = &usb_ifnum_to_if(chip->dev, ctrlif)->altsetting[0];
> > > switch (get_iface_desc(mixer->hostif)->bInterfaceProtocol) {
> > > diff --git a/sound/usb/mixer.h b/sound/usb/mixer.h
> > > index 167fbfcf01ac..30dd30b925fc 100644
> > > --- a/sound/usb/mixer.h
> > > +++ b/sound/usb/mixer.h
> > > @@ -19,8 +19,6 @@ struct usb_mixer_interface {
> > > struct list_head list;
> > > unsigned int ignore_ctl_error;
> > > struct urb *urb;
> > > - /* array[MAX_ID_ELEMS], indexed by unit id */
> > > - struct usb_mixer_elem_list **id_elems;
> > >
> > > /* the usb audio specification version this interface complies to */
> > > int protocol;
> > > @@ -42,6 +40,9 @@ struct usb_mixer_interface {
> > > void *private_data;
> > > void (*private_free)(struct usb_mixer_interface *mixer);
> > > void (*private_suspend)(struct usb_mixer_interface *mixer);
> > > +
> > > + /* array[MAX_ID_ELEMS], indexed by unit id */
> > > + struct usb_mixer_elem_list *id_elems[];
> > > };
> > >
> > > #define MAX_CHANNELS 16 /* max logical channels */
> > > --
> > > 2.53.0
> > >
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] ALSA: usb-audio: use kzalloc_flex
2026-03-13 22:02 ` Rosen Penev
@ 2026-03-14 13:29 ` Takashi Iwai
0 siblings, 0 replies; 5+ messages in thread
From: Takashi Iwai @ 2026-03-14 13:29 UTC (permalink / raw)
To: Rosen Penev
Cc: Takashi Iwai, linux-sound, Jaroslav Kysela, Takashi Iwai,
open list
On Fri, 13 Mar 2026 23:02:08 +0100,
Rosen Penev wrote:
>
> On Wed, Mar 11, 2026 at 11:45 PM Rosen Penev <rosenp@gmail.com> wrote:
> >
> > On Wed, Mar 11, 2026 at 11:34 PM Takashi Iwai <tiwai@suse.de> wrote:
> > >
> > > On Thu, 12 Mar 2026 00:27:48 +0100,
> > > Rosen Penev wrote:
> > > >
> > > > Saves one allocation by using a flexible array member.
> > >
> > > As it's a fixed size array, it doesn't have to be a flex array at all,
> > > so it can be even simpler.
> > That's true. The comment even admits as such. Wonder why it was ever a
> > pointer allocated with calloc...
> Oh no I see the issue:
>
> sound/usb/mixer.c:#define MAX_ID_ELEMS 256
>
> I don't think this is supposed to be in the header.
Why?
Takashi
^ permalink raw reply [flat|nested] 5+ messages in thread
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2026-03-11 23:27 [PATCH] ALSA: usb-audio: use kzalloc_flex Rosen Penev
2026-03-12 6:34 ` Takashi Iwai
2026-03-12 6:45 ` Rosen Penev
2026-03-13 22:02 ` Rosen Penev
2026-03-14 13:29 ` Takashi Iwai
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