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ALSA: control: Introduce unlocked version for snd_ctl_find_*() helpers

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For reducing the unnecessary use of controls_rwsem in the drivers,
this patch adds a new variant for snd_ctl_find_*() helpers:
snd_ctl_find_id_locked() and snd_ctl_find_numid_locked() look for a
kctl element inside the card->controls_rwsem -- that is, doing the
very same as what snd_ctl_find_id() and snd_ctl_find_numid() did until
now.  snd_ctl_find_id() and snd_ctl_find_numid() remain same,
i.e. still unlocked version, but they will be switched to locked
version once after all callers are replaced.

The patch also replaces the calls of snd_ctl_find_id() and
snd_ctl_find_numid() in a few places; all of those are places where we
know that the functions are called properly with controls_rwsem held.
All others are without rwsem (although they should have been).

After this patch, we'll turn on the locking in snd_ctl_find_id() and
snd_ctl_find_numid() to be more race-free.

Link: https://lore.kernel.org/r/20230718141304.1032-10-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2023-07-18 16:13:02 +02:00
parent 6723670a48
commit b1e055f676
6 changed files with 61 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/sound/control.h
View File

@ -140,7 +140,9 @@ 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_numid_locked(struct snd_card *card, unsigned int numid);
struct snd_kcontrol *snd_ctl_find_numid(struct snd_card *card, unsigned int numid);
struct snd_kcontrol *snd_ctl_find_id_locked(struct snd_card *card, const struct snd_ctl_elem_id *id);
struct snd_kcontrol *snd_ctl_find_id(struct snd_card *card, const struct snd_ctl_elem_id *id);
int snd_ctl_create(struct snd_card *card);

69
sound/core/control.c
View File

@ -475,7 +475,7 @@ static int __snd_ctl_add_replace(struct snd_card *card,
if (id.index > UINT_MAX - kcontrol->count)
return -EINVAL;
old = snd_ctl_find_id(card, &id);
old = snd_ctl_find_id_locked(card, &id);
if (!old) {
if (mode == CTL_REPLACE)
return -EINVAL;
@ -641,7 +641,7 @@ int snd_ctl_remove_id(struct snd_card *card, struct snd_ctl_elem_id *id)
int ret;
down_write(&card->controls_rwsem);
kctl = snd_ctl_find_id(card, id);
kctl = snd_ctl_find_id_locked(card, id);
if (kctl == NULL) {
up_write(&card->controls_rwsem);
return -ENOENT;
@ -670,7 +670,7 @@ static int snd_ctl_remove_user_ctl(struct snd_ctl_file * file,
int idx, ret;
down_write(&card->controls_rwsem);
kctl = snd_ctl_find_id(card, id);
kctl = snd_ctl_find_id_locked(card, id);
if (kctl == NULL) {
ret = -ENOENT;
goto error;
@ -711,7 +711,7 @@ int snd_ctl_activate_id(struct snd_card *card, struct snd_ctl_elem_id *id,
int ret;
down_write(&card->controls_rwsem);
kctl = snd_ctl_find_id(card, id);
kctl = snd_ctl_find_id_locked(card, id);
if (kctl == NULL) {
ret = -ENOENT;
goto unlock;
@ -765,7 +765,7 @@ int snd_ctl_rename_id(struct snd_card *card, struct snd_ctl_elem_id *src_id,
int saved_numid;
down_write(&card->controls_rwsem);
kctl = snd_ctl_find_id(card, src_id);
kctl = snd_ctl_find_id_locked(card, src_id);
if (kctl == NULL) {
up_write(&card->controls_rwsem);
return -ENOENT;
@ -820,7 +820,7 @@ snd_ctl_find_numid_slow(struct snd_card *card, unsigned int numid)
#endif /* !CONFIG_SND_CTL_FAST_LOOKUP */
/**
* snd_ctl_find_numid - find the control instance with the given number-id
* snd_ctl_find_numid_locked - find the control instance with the given number-id
* @card: the card instance
* @numid: the number-id to search
*
@ -830,9 +830,9 @@ snd_ctl_find_numid_slow(struct snd_card *card, unsigned int numid)
* (if the race condition can happen).
*
* Return: The pointer of the instance if found, or %NULL if not.
*
*/
struct snd_kcontrol *snd_ctl_find_numid(struct snd_card *card, unsigned int numid)
struct snd_kcontrol *
snd_ctl_find_numid_locked(struct snd_card *card, unsigned int numid)
{
if (snd_BUG_ON(!card || !numid))
return NULL;
@ -842,10 +842,26 @@ struct snd_kcontrol *snd_ctl_find_numid(struct snd_card *card, unsigned int numi
return snd_ctl_find_numid_slow(card, numid);
#endif
}
EXPORT_SYMBOL(snd_ctl_find_numid_locked);
/**
* snd_ctl_find_numid - find the control instance with the given number-id
* @card: the card instance
* @numid: the number-id to search
*
* Finds the control instance with the given number-id from the card.
*
* Return: The pointer of the instance if found, or %NULL if not.
*/
struct snd_kcontrol *snd_ctl_find_numid(struct snd_card *card,
unsigned int numid)
{
return snd_ctl_find_numid_locked(card, numid);
}
EXPORT_SYMBOL(snd_ctl_find_numid);
/**
* snd_ctl_find_id - find the control instance with the given id
* snd_ctl_find_id_locked - find the control instance with the given id
* @card: the card instance
* @id: the id to search
*
@ -855,17 +871,16 @@ EXPORT_SYMBOL(snd_ctl_find_numid);
* (if the race condition can happen).
*
* Return: The pointer of the instance if found, or %NULL if not.
*
*/
struct snd_kcontrol *snd_ctl_find_id(struct snd_card *card,
const struct snd_ctl_elem_id *id)
struct snd_kcontrol *snd_ctl_find_id_locked(struct snd_card *card,
const struct snd_ctl_elem_id *id)
{
struct snd_kcontrol *kctl;
if (snd_BUG_ON(!card || !id))
return NULL;
if (id->numid != 0)
return snd_ctl_find_numid(card, id->numid);
return snd_ctl_find_numid_locked(card, id->numid);
#ifdef CONFIG_SND_CTL_FAST_LOOKUP
kctl = xa_load(&card->ctl_hash, get_ctl_id_hash(id));
if (kctl && elem_id_matches(kctl, id))
@ -880,6 +895,22 @@ struct snd_kcontrol *snd_ctl_find_id(struct snd_card *card,
return NULL;
}
EXPORT_SYMBOL(snd_ctl_find_id_locked);
/**
* snd_ctl_find_id - find the control instance with the given id
* @card: the card instance
* @id: the id to search
*
* Finds the control instance with the given id from the card.
*
* Return: The pointer of the instance if found, or %NULL if not.
*/
struct snd_kcontrol *snd_ctl_find_id(struct snd_card *card,
const struct snd_ctl_elem_id *id)
{
return snd_ctl_find_id_locked(card, id);
}
EXPORT_SYMBOL(snd_ctl_find_id);
static int snd_ctl_card_info(struct snd_card *card, struct snd_ctl_file * ctl,
@ -1194,7 +1225,7 @@ static int snd_ctl_elem_info(struct snd_ctl_file *ctl,
int result;
down_read(&card->controls_rwsem);
kctl = snd_ctl_find_id(card, &info->id);
kctl = snd_ctl_find_id_locked(card, &info->id);
if (kctl == NULL)
result = -ENOENT;
else
@ -1233,7 +1264,7 @@ static int snd_ctl_elem_read(struct snd_card *card,
int ret;
down_read(&card->controls_rwsem);
kctl = snd_ctl_find_id(card, &control->id);
kctl = snd_ctl_find_id_locked(card, &control->id);
if (kctl == NULL) {
ret = -ENOENT;
goto unlock;
@ -1310,7 +1341,7 @@ static int snd_ctl_elem_write(struct snd_card *card, struct snd_ctl_file *file,
int result;
down_write(&card->controls_rwsem);
kctl = snd_ctl_find_id(card, &control->id);
kctl = snd_ctl_find_id_locked(card, &control->id);
if (kctl == NULL) {
up_write(&card->controls_rwsem);
return -ENOENT;
@ -1391,7 +1422,7 @@ static int snd_ctl_elem_lock(struct snd_ctl_file *file,
if (copy_from_user(&id, _id, sizeof(id)))
return -EFAULT;
down_write(&card->controls_rwsem);
kctl = snd_ctl_find_id(card, &id);
kctl = snd_ctl_find_id_locked(card, &id);
if (kctl == NULL) {
result = -ENOENT;
} else {
@ -1419,7 +1450,7 @@ static int snd_ctl_elem_unlock(struct snd_ctl_file *file,
if (copy_from_user(&id, _id, sizeof(id)))
return -EFAULT;
down_write(&card->controls_rwsem);
kctl = snd_ctl_find_id(card, &id);
kctl = snd_ctl_find_id_locked(card, &id);
if (kctl == NULL) {
result = -ENOENT;
} else {
@ -1927,7 +1958,7 @@ static int snd_ctl_tlv_ioctl(struct snd_ctl_file *file,
container_size = header.length;
container = buf->tlv;
kctl = snd_ctl_find_numid(file->card, header.numid);
kctl = snd_ctl_find_numid_locked(file->card, header.numid);
if (kctl == NULL)
return -ENOENT;

2
sound/core/control_compat.c
View File

@ -173,7 +173,7 @@ static int get_ctl_type(struct snd_card *card, struct snd_ctl_elem_id *id,
int err;
down_read(&card->controls_rwsem);
kctl = snd_ctl_find_id(card, id);
kctl = snd_ctl_find_id_locked(card, id);
if (! kctl) {
up_read(&card->controls_rwsem);
return -ENOENT;

2
sound/core/control_led.c
View File

@ -251,7 +251,7 @@ static int snd_ctl_led_set_id(int card_number, struct snd_ctl_elem_id *id,
card = snd_card_ref(card_number);
if (card) {
down_write(&card->controls_rwsem);
kctl = snd_ctl_find_id(card, id);
kctl = snd_ctl_find_id_locked(card, id);
if (kctl) {
ioff = snd_ctl_get_ioff(kctl, id);
vd = &kctl->vd[ioff];

10
sound/core/oss/mixer_oss.c
View File

@ -524,7 +524,7 @@ static struct snd_kcontrol *snd_mixer_oss_test_id(struct snd_mixer_oss *mixer, c
id.iface = SNDRV_CTL_ELEM_IFACE_MIXER;
strscpy(id.name, name, sizeof(id.name));
id.index = index;
return snd_ctl_find_id(card, &id);
return snd_ctl_find_id_locked(card, &id);
}
static void snd_mixer_oss_get_volume1_vol(struct snd_mixer_oss_file *fmixer,
@ -540,7 +540,7 @@ static void snd_mixer_oss_get_volume1_vol(struct snd_mixer_oss_file *fmixer,
if (numid == ID_UNKNOWN)
return;
down_read(&card->controls_rwsem);
kctl = snd_ctl_find_numid(card, numid);
kctl = snd_ctl_find_numid_locked(card, numid);
if (!kctl) {
up_read(&card->controls_rwsem);
return;
@ -579,7 +579,7 @@ static void snd_mixer_oss_get_volume1_sw(struct snd_mixer_oss_file *fmixer,
if (numid == ID_UNKNOWN)
return;
down_read(&card->controls_rwsem);
kctl = snd_ctl_find_numid(card, numid);
kctl = snd_ctl_find_numid_locked(card, numid);
if (!kctl) {
up_read(&card->controls_rwsem);
return;
@ -645,7 +645,7 @@ static void snd_mixer_oss_put_volume1_vol(struct snd_mixer_oss_file *fmixer,
if (numid == ID_UNKNOWN)
return;
down_read(&card->controls_rwsem);
kctl = snd_ctl_find_numid(card, numid);
kctl = snd_ctl_find_numid_locked(card, numid);
if (!kctl) {
up_read(&card->controls_rwsem);
return;
@ -688,7 +688,7 @@ static void snd_mixer_oss_put_volume1_sw(struct snd_mixer_oss_file *fmixer,
if (numid == ID_UNKNOWN)
return;
down_read(&card->controls_rwsem);
kctl = snd_ctl_find_numid(card, numid);
kctl = snd_ctl_find_numid_locked(card, numid);
if (!kctl) {
up_read(&card->controls_rwsem);
return;

2
sound/pci/emu10k1/emufx.c
View File

@ -800,7 +800,7 @@ static int snd_emu10k1_verify_controls(struct snd_emu10k1 *emu,
continue;
gctl_id = (struct snd_ctl_elem_id *)&gctl->id;
down_read(&emu->card->controls_rwsem);
if (snd_ctl_find_id(emu->card, gctl_id)) {
if (snd_ctl_find_id_locked(emu->card, gctl_id)) {
up_read(&emu->card->controls_rwsem);
err = -EEXIST;
goto __error;