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.
Signed-off-by: Takashi Iwai tiwai@suse.de --- include/sound/control.h | 4 ++- sound/core/control.c | 69 +++++++++++++++++++++++++++---------- sound/core/control_compat.c | 2 +- sound/core/control_led.c | 2 +- sound/core/oss/mixer_oss.c | 10 +++--- sound/pci/emu10k1/emufx.c | 2 +- 6 files changed, 61 insertions(+), 28 deletions(-)
diff --git a/include/sound/control.h b/include/sound/control.h index e61b749bf204..42e8dbb22d8e 100644 --- a/include/sound/control.h +++ b/include/sound/control.h @@ -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); diff --git a/sound/core/control.c b/sound/core/control.c index 180e5768a10f..30741293708d 100644 --- a/sound/core/control.c +++ b/sound/core/control.c @@ -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;
diff --git a/sound/core/control_compat.c b/sound/core/control_compat.c index 9cae5d74335c..0e8b1bfb040e 100644 --- a/sound/core/control_compat.c +++ b/sound/core/control_compat.c @@ -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; diff --git a/sound/core/control_led.c b/sound/core/control_led.c index ee77547bf8dc..67fc2a1dcf7a 100644 --- a/sound/core/control_led.c +++ b/sound/core/control_led.c @@ -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]; diff --git a/sound/core/oss/mixer_oss.c b/sound/core/oss/mixer_oss.c index 9620115cfdc0..dae2da380835 100644 --- a/sound/core/oss/mixer_oss.c +++ b/sound/core/oss/mixer_oss.c @@ -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; diff --git a/sound/pci/emu10k1/emufx.c b/sound/pci/emu10k1/emufx.c index 70c8252a92d9..318a064f2cec 100644 --- a/sound/pci/emu10k1/emufx.c +++ b/sound/pci/emu10k1/emufx.c @@ -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;