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ALSA: control: obsolete user_ctl_lock 

At a previous commit, concurrent requests for TLV data are maintained
exclusively between read requests and write/command requests. TLV
callback handlers in each driver has no risk from concurrent access for
reference/change.

In current implementation, 'struct snd_card' has a mutex to control
concurrent accesses to user-defined element sets. This commit obsoletes it.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Sakamoto 2017-08-03 20:20:42 +09:00 committed by Takashi Iwai
parent 4c8099e9ca
commit 30d8340b58
3 changed files with 14 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/sound/core.h
View File

@ -118,8 +118,6 @@ struct snd_card {
int user_ctl_count; /* count of all user controls */
struct list_head controls; /* all controls for this card */
struct list_head ctl_files; /* active control files */
struct mutex user_ctl_lock; /* protects user controls against
concurrent access */
struct snd_info_entry *proc_root; /* root for soundcard specific files */
struct snd_info_entry *proc_id; /* the card id */

39
sound/core/control.c
View File

@ -1095,9 +1095,7 @@ static int snd_ctl_elem_user_get(struct snd_kcontrol *kcontrol,
char *src = ue->elem_data +
snd_ctl_get_ioff(kcontrol, &ucontrol->id) * size;
mutex_lock(&ue->card->user_ctl_lock);
memcpy(&ucontrol->value, src, size);
mutex_unlock(&ue->card->user_ctl_lock);
return 0;
}
@ -1110,11 +1108,9 @@ static int snd_ctl_elem_user_put(struct snd_kcontrol *kcontrol,
char *dst = ue->elem_data +
snd_ctl_get_ioff(kcontrol, &ucontrol->id) * size;
mutex_lock(&ue->card->user_ctl_lock);
change = memcmp(&ucontrol->value, dst, size) != 0;
if (change)
memcpy(dst, &ucontrol->value, size);
mutex_unlock(&ue->card->user_ctl_lock);
return change;
}
@ -1124,44 +1120,37 @@ static int snd_ctl_elem_user_tlv(struct snd_kcontrol *kcontrol,
unsigned int __user *tlv)
{
struct user_element *ue = kcontrol->private_data;
int change = 0;
void *new_data;
if (op_flag == SNDRV_CTL_TLV_OP_WRITE) {
int change;
void *new_data;
if (size > 1024 * 128) /* sane value */
return -EINVAL;
new_data = memdup_user(tlv, size);
if (IS_ERR(new_data))
return PTR_ERR(new_data);
mutex_lock(&ue->card->user_ctl_lock);
change = ue->tlv_data_size != size;
if (!change)
change = memcmp(ue->tlv_data, new_data, size);
kfree(ue->tlv_data);
ue->tlv_data = new_data;
ue->tlv_data_size = size;
mutex_unlock(&ue->card->user_ctl_lock);
} else {
int ret = 0;
mutex_lock(&ue->card->user_ctl_lock);
if (!ue->tlv_data_size || !ue->tlv_data) {
ret = -ENXIO;
goto err_unlock;
}
if (size < ue->tlv_data_size) {
ret = -ENOSPC;
goto err_unlock;
}
return change;
} else {
if (!ue->tlv_data_size || !ue->tlv_data)
return -ENXIO;
if (size < ue->tlv_data_size)
return -ENOSPC;
if (copy_to_user(tlv, ue->tlv_data, ue->tlv_data_size))
ret = -EFAULT;
err_unlock:
mutex_unlock(&ue->card->user_ctl_lock);
if (ret)
return ret;
return -EFAULT;
return 0;
}
return change;
}
static int snd_ctl_elem_init_enum_names(struct user_element *ue)

1
sound/core/init.c
View File

@ -248,7 +248,6 @@ int snd_card_new(struct device *parent, int idx, const char *xid,
INIT_LIST_HEAD(&card->devices);
init_rwsem(&card->controls_rwsem);
rwlock_init(&card->ctl_files_rwlock);
mutex_init(&card->user_ctl_lock);
INIT_LIST_HEAD(&card->controls);
INIT_LIST_HEAD(&card->ctl_files);
spin_lock_init(&card->files_lock);