For a fast look-up of a control element via either numid or name
matching (enabled via CONFIG_SND_CTL_FAST_LOOKUP), a locking isn't
needed at all thanks to Xarray. OTOH, the locking is still needed for
a slow linked-list traversal, and that's rather a rare case.
In this patch, we reduce the use of locking at snd_ctl_find_*() API
functions, and switch from controls_rwsem to controls_rwlock for
avoiding unnecessary lock inversions. This also resulted in a nice
cleanup, as *_unlocked() version of snd_ctl_find_*() APIs can be
dropped.
snd_ctl_find_id_mixer_unlocked() is still left just as an alias of
snd_ctl_find_id_mixer(), since soc-card.c has a wrapper and there are
several users. Once after converting there, we can remove it later.
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
include/sound/control.h | 22 +-----
include/sound/core.h | 2 +-
sound/core/control.c | 141 ++++++++++++++----------------------
sound/core/control_compat.c | 2 +-
sound/core/control_led.c | 2 +-
sound/core/oss/mixer_oss.c | 10 +--
6 files changed, 64 insertions(+), 115 deletions(-)
diff --git a/include/sound/control.h b/include/sound/control.h
index 13511c50825f..6f9d3b8350ce 100644
--- a/include/sound/control.h
+++ b/include/sound/control.h
@@ -140,9 +140,7 @@ 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_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);
/**
@@ -167,27 +165,11 @@ snd_ctl_find_id_mixer(struct snd_card *card, const char *name)
return snd_ctl_find_id(card, &id);
}
-/**
- * snd_ctl_find_id_mixer_locked - find the control instance with the given name string
- * @card: the card instance
- * @name: the name string
- *
- * Finds the control instance with the given name and
- * @SNDRV_CTL_ELEM_IFACE_MIXER. Other fields are set to zero.
- *
- * This is merely a wrapper to snd_ctl_find_id_locked().
- * The caller must down card->controls_rwsem before calling this function.
- *
- * Return: The pointer of the instance if found, or %NULL if not.
- */
+/* to be removed */
static inline struct snd_kcontrol *
snd_ctl_find_id_mixer_locked(struct snd_card *card, const char *name)
{
- struct snd_ctl_elem_id id = {};
-
- id.iface = SNDRV_CTL_ELEM_IFACE_MIXER;
- strscpy(id.name, name, sizeof(id.name));
- return snd_ctl_find_id_locked(card, &id);
+ return snd_ctl_find_id_mixer(card, name);
}
int snd_ctl_create(struct snd_card *card);
diff --git a/include/sound/core.h b/include/sound/core.h
index 55607e91d5fd..5c418ab24aa4 100644
--- a/include/sound/core.h
+++ b/include/sound/core.h
@@ -99,7 +99,7 @@ struct snd_card {
struct device *ctl_dev; /* control device */
unsigned int last_numid; /* last used numeric ID */
struct rw_semaphore controls_rwsem; /* controls lock (list and values) */
- rwlock_t controls_rwlock; /* lock for ctl_files list */
+ rwlock_t controls_rwlock; /* lock for lookup and ctl_files list */
int controls_count; /* count of all controls */
size_t user_ctl_alloc_size; // current memory allocation by user controls.
struct list_head controls; /* all controls for this card */
diff --git a/sound/core/control.c b/sound/core/control.c
index ae209dcfd049..7d7d592a8428 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -470,7 +470,7 @@ static int __snd_ctl_add_replace(struct snd_card *card,
if (id.index > UINT_MAX - kcontrol->count)
return -EINVAL;
- old = snd_ctl_find_id_locked(card, &id);
+ old = snd_ctl_find_id(card, &id);
if (!old) {
if (mode == CTL_REPLACE)
return -EINVAL;
@@ -491,10 +491,12 @@ static int __snd_ctl_add_replace(struct snd_card *card,
if (snd_ctl_find_hole(card, kcontrol->count) < 0)
return -ENOMEM;
- list_add_tail(&kcontrol->list, &card->controls);
- card->controls_count += kcontrol->count;
- kcontrol->id.numid = card->last_numid + 1;
- card->last_numid += kcontrol->count;
+ scoped_guard(write_lock_irq, &card->controls_rwlock) {
+ list_add_tail(&kcontrol->list, &card->controls);
+ card->controls_count += kcontrol->count;
+ kcontrol->id.numid = card->last_numid + 1;
+ card->last_numid += kcontrol->count;
+ }
add_hash_entries(card, kcontrol);
@@ -579,12 +581,15 @@ static int __snd_ctl_remove(struct snd_card *card,
if (snd_BUG_ON(!card || !kcontrol))
return -EINVAL;
- list_del(&kcontrol->list);
if (remove_hash)
remove_hash_entries(card, kcontrol);
- card->controls_count -= kcontrol->count;
+ scoped_guard(write_lock_irq, &card->controls_rwlock) {
+ list_del(&kcontrol->list);
+ card->controls_count -= kcontrol->count;
+ }
+
for (idx = 0; idx < kcontrol->count; idx++)
snd_ctl_notify_one(card, SNDRV_CTL_EVENT_MASK_REMOVE, kcontrol, idx);
snd_ctl_free_one(kcontrol);
@@ -634,7 +639,7 @@ int snd_ctl_remove_id(struct snd_card *card, struct snd_ctl_elem_id *id)
struct snd_kcontrol *kctl;
guard(rwsem_write)(&card->controls_rwsem);
- kctl = snd_ctl_find_id_locked(card, id);
+ kctl = snd_ctl_find_id(card, id);
if (kctl == NULL)
return -ENOENT;
return snd_ctl_remove_locked(card, kctl);
@@ -659,7 +664,7 @@ static int snd_ctl_remove_user_ctl(struct snd_ctl_file * file,
int idx;
guard(rwsem_write)(&card->controls_rwsem);
- kctl = snd_ctl_find_id_locked(card, id);
+ kctl = snd_ctl_find_id(card, id);
if (kctl == NULL)
return -ENOENT;
if (!(kctl->vd[0].access & SNDRV_CTL_ELEM_ACCESS_USER))
@@ -691,7 +696,7 @@ 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_locked(card, id);
+ kctl = snd_ctl_find_id(card, id);
if (kctl == NULL) {
ret = -ENOENT;
goto unlock;
@@ -745,7 +750,7 @@ int snd_ctl_rename_id(struct snd_card *card, struct snd_ctl_elem_id *src_id,
int saved_numid;
guard(rwsem_write)(&card->controls_rwsem);
- kctl = snd_ctl_find_id_locked(card, src_id);
+ kctl = snd_ctl_find_id(card, src_id);
if (kctl == NULL)
return -ENOENT;
saved_numid = kctl->id.numid;
@@ -787,6 +792,7 @@ snd_ctl_find_numid_slow(struct snd_card *card, unsigned int numid)
{
struct snd_kcontrol *kctl;
+ guard(read_lock_irqsave)(&card->controls_rwlock);
list_for_each_entry(kctl, &card->controls, list) {
if (kctl->id.numid <= numid && kctl->id.numid + kctl->count > numid)
return kctl;
@@ -795,32 +801,6 @@ snd_ctl_find_numid_slow(struct snd_card *card, unsigned int numid)
}
#endif /* !CONFIG_SND_CTL_FAST_LOOKUP */
-/**
- * snd_ctl_find_numid_locked - 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.
- *
- * The caller must down card->controls_rwsem before calling this function
- * (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_locked(struct snd_card *card, unsigned int numid)
-{
- if (snd_BUG_ON(!card || !numid))
- return NULL;
- lockdep_assert_held(&card->controls_rwsem);
-#ifdef CONFIG_SND_CTL_FAST_LOOKUP
- return xa_load(&card->ctl_numids, numid);
-#else
- 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
@@ -830,54 +810,22 @@ EXPORT_SYMBOL(snd_ctl_find_numid_locked);
*
* Return: The pointer of the instance if found, or %NULL if not.
*
- * Note that this function takes card->controls_rwsem lock internally.
+ * Note that this function takes card->controls_rwlock lock internally.
*/
struct snd_kcontrol *snd_ctl_find_numid(struct snd_card *card,
unsigned int numid)
{
- guard(rwsem_read)(&card->controls_rwsem);
- return snd_ctl_find_numid_locked(card, numid);
+ if (snd_BUG_ON(!card || !numid))
+ return NULL;
+
+#ifdef CONFIG_SND_CTL_FAST_LOOKUP
+ return xa_load(&card->ctl_numids, numid);
+#else
+ return snd_ctl_find_numid_slow(card, numid);
+#endif
}
EXPORT_SYMBOL(snd_ctl_find_numid);
-/**
- * snd_ctl_find_id_locked - 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.
- *
- * The caller must down card->controls_rwsem before calling this function
- * (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_locked(struct snd_card *card,
- const struct snd_ctl_elem_id *id)
-{
- struct snd_kcontrol *kctl;
-
- if (snd_BUG_ON(!card || !id))
- return NULL;
- lockdep_assert_held(&card->controls_rwsem);
- if (id->numid != 0)
- 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))
- return kctl;
- if (!card->ctl_hash_collision)
- return NULL; /* we can rely on only hash table */
-#endif
- /* no matching in hash table - try all as the last resort */
- list_for_each_entry(kctl, &card->controls, list)
- if (elem_id_matches(kctl, id))
- return kctl;
-
- 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
@@ -887,13 +835,32 @@ EXPORT_SYMBOL(snd_ctl_find_id_locked);
*
* Return: The pointer of the instance if found, or %NULL if not.
*
- * Note that this function takes card->controls_rwsem lock internally.
+ * Note that this function takes card->controls_rwlock lock internally.
*/
struct snd_kcontrol *snd_ctl_find_id(struct snd_card *card,
const struct snd_ctl_elem_id *id)
{
- guard(rwsem_read)(&card->controls_rwsem);
- return snd_ctl_find_id_locked(card, 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);
+#ifdef CONFIG_SND_CTL_FAST_LOOKUP
+ kctl = xa_load(&card->ctl_hash, get_ctl_id_hash(id));
+ if (kctl && elem_id_matches(kctl, id))
+ return kctl;
+ if (!card->ctl_hash_collision)
+ return NULL; /* we can rely on only hash table */
+#endif
+ /* no matching in hash table - try all as the last resort */
+ guard(read_lock_irqsave)(&card->controls_rwlock);
+ list_for_each_entry(kctl, &card->controls, list)
+ if (elem_id_matches(kctl, id))
+ return kctl;
+
+ return NULL;
}
EXPORT_SYMBOL(snd_ctl_find_id);
@@ -1196,7 +1163,7 @@ static int snd_ctl_elem_info(struct snd_ctl_file *ctl,
struct snd_kcontrol *kctl;
guard(rwsem_read)(&card->controls_rwsem);
- kctl = snd_ctl_find_id_locked(card, &info->id);
+ kctl = snd_ctl_find_id(card, &info->id);
if (!kctl)
return -ENOENT;
return __snd_ctl_elem_info(card, kctl, info, ctl);
@@ -1237,7 +1204,7 @@ static int snd_ctl_elem_read(struct snd_card *card,
int ret;
guard(rwsem_read)(&card->controls_rwsem);
- kctl = snd_ctl_find_id_locked(card, &control->id);
+ kctl = snd_ctl_find_id(card, &control->id);
if (!kctl)
return -ENOENT;
@@ -1306,7 +1273,7 @@ static int snd_ctl_elem_write(struct snd_card *card, struct snd_ctl_file *file,
int result = 0;
down_write(&card->controls_rwsem);
- kctl = snd_ctl_find_id_locked(card, &control->id);
+ kctl = snd_ctl_find_id(card, &control->id);
if (kctl == NULL) {
up_write(&card->controls_rwsem);
return -ENOENT;
@@ -1386,7 +1353,7 @@ static int snd_ctl_elem_lock(struct snd_ctl_file *file,
if (copy_from_user(&id, _id, sizeof(id)))
return -EFAULT;
guard(rwsem_write)(&card->controls_rwsem);
- kctl = snd_ctl_find_id_locked(card, &id);
+ kctl = snd_ctl_find_id(card, &id);
if (!kctl)
return -ENOENT;
vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
@@ -1407,7 +1374,7 @@ static int snd_ctl_elem_unlock(struct snd_ctl_file *file,
if (copy_from_user(&id, _id, sizeof(id)))
return -EFAULT;
guard(rwsem_write)(&card->controls_rwsem);
- kctl = snd_ctl_find_id_locked(card, &id);
+ kctl = snd_ctl_find_id(card, &id);
if (!kctl)
return -ENOENT;
vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
@@ -1904,7 +1871,7 @@ static int snd_ctl_tlv_ioctl(struct snd_ctl_file *file,
container_size = header.length;
container = buf->tlv;
- kctl = snd_ctl_find_numid_locked(file->card, header.numid);
+ kctl = snd_ctl_find_numid(file->card, header.numid);
if (kctl == NULL)
return -ENOENT;
diff --git a/sound/core/control_compat.c b/sound/core/control_compat.c
index 934bb945e702..401c12e62816 100644
--- a/sound/core/control_compat.c
+++ b/sound/core/control_compat.c
@@ -168,7 +168,7 @@ static int get_ctl_type(struct snd_card *card, struct snd_ctl_elem_id *id,
int err;
guard(rwsem_read)(&card->controls_rwsem);
- kctl = snd_ctl_find_id_locked(card, id);
+ kctl = snd_ctl_find_id(card, id);
if (!kctl)
return -ENOENT;
info = kzalloc(sizeof(*info), GFP_KERNEL);
diff --git a/sound/core/control_led.c b/sound/core/control_led.c
index 804805a95e2f..14eb3e6cc94c 100644
--- a/sound/core/control_led.c
+++ b/sound/core/control_led.c
@@ -254,7 +254,7 @@ static int snd_ctl_led_set_id(int card_number, struct snd_ctl_elem_id *id,
if (!card)
return -ENXIO;
guard(rwsem_write)(&card->controls_rwsem);
- kctl = snd_ctl_find_id_locked(card, id);
+ kctl = snd_ctl_find_id(card, id);
if (!kctl)
return -ENOENT;
ioff = snd_ctl_get_ioff(kctl, id);
diff --git a/sound/core/oss/mixer_oss.c b/sound/core/oss/mixer_oss.c
index 6a0508093ea6..33bf9a220ada 100644
--- a/sound/core/oss/mixer_oss.c
+++ b/sound/core/oss/mixer_oss.c
@@ -510,7 +510,7 @@ 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_locked(card, &id);
+ return snd_ctl_find_id(card, &id);
}
static void snd_mixer_oss_get_volume1_vol(struct snd_mixer_oss_file *fmixer,
@@ -526,7 +526,7 @@ static void snd_mixer_oss_get_volume1_vol(struct snd_mixer_oss_file *fmixer,
if (numid == ID_UNKNOWN)
return;
guard(rwsem_read)(&card->controls_rwsem);
- kctl = snd_ctl_find_numid_locked(card, numid);
+ kctl = snd_ctl_find_numid(card, numid);
if (!kctl)
return;
uinfo = kzalloc(sizeof(*uinfo), GFP_KERNEL);
@@ -559,7 +559,7 @@ static void snd_mixer_oss_get_volume1_sw(struct snd_mixer_oss_file *fmixer,
if (numid == ID_UNKNOWN)
return;
guard(rwsem_read)(&card->controls_rwsem);
- kctl = snd_ctl_find_numid_locked(card, numid);
+ kctl = snd_ctl_find_numid(card, numid);
if (!kctl)
return;
uinfo = kzalloc(sizeof(*uinfo), GFP_KERNEL);
@@ -619,7 +619,7 @@ static void snd_mixer_oss_put_volume1_vol(struct snd_mixer_oss_file *fmixer,
if (numid == ID_UNKNOWN)
return;
guard(rwsem_read)(&card->controls_rwsem);
- kctl = snd_ctl_find_numid_locked(card, numid);
+ kctl = snd_ctl_find_numid(card, numid);
if (!kctl)
return;
uinfo = kzalloc(sizeof(*uinfo), GFP_KERNEL);
@@ -656,7 +656,7 @@ static void snd_mixer_oss_put_volume1_sw(struct snd_mixer_oss_file *fmixer,
if (numid == ID_UNKNOWN)
return;
guard(rwsem_read)(&card->controls_rwsem);
- kctl = snd_ctl_find_numid_locked(card, numid);
+ kctl = snd_ctl_find_numid(card, numid);
if (!kctl)
return;
uinfo = kzalloc(sizeof(*uinfo), GFP_KERNEL);
--
2.43.0
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