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ALSA: ak411x: Fix stall in work callback 

commit 4161b4505f upstream.

When ak4114 work calls its callback and the callback invokes
ak4114_reinit(), it stalls due to flush_delayed_work().  For avoiding
this, control the reentrance by introducing a refcount.  Also
flush_delayed_work() is replaced with cancel_delayed_work_sync().

The exactly same bug is present in ak4113.c and fixed as well.

Reported-by: Pavel Hofman <pavel.hofman@ivitera.com>
Acked-by: Jaroslav Kysela <perex@perex.cz>
Tested-by: Pavel Hofman <pavel.hofman@ivitera.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Takashi Iwai 2015-01-13 10:53:20 +01:00 committed by Greg Kroah-Hartman
parent 48e81ac2e3
commit 2451dcefc2
4 changed files with 18 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/sound/ak4113.h
View File

@ -286,7 +286,7 @@ struct ak4113 {
ak4113_write_t *write;
ak4113_read_t *read;
void *private_data;
unsigned int init:1;
atomic_t wq_processing;
spinlock_t lock;
unsigned char regmap[AK4113_WRITABLE_REGS];
struct snd_kcontrol *kctls[AK4113_CONTROLS];

2
include/sound/ak4114.h
View File

@ -168,7 +168,7 @@ struct ak4114 {
ak4114_write_t * write;
ak4114_read_t * read;
void * private_data;
unsigned int init: 1;
atomic_t wq_processing;
spinlock_t lock;
unsigned char regmap[6];
unsigned char txcsb[5];

17
sound/i2c/other/ak4113.c
View File

@ -56,8 +56,7 @@ static inline unsigned char reg_read(struct ak4113 *ak4113, unsigned char reg)
static void snd_ak4113_free(struct ak4113 *chip)
{
chip->init = 1; /* don't schedule new work */
mb();
atomic_inc(&chip->wq_processing); /* don't schedule new work */
cancel_delayed_work_sync(&chip->work);
kfree(chip);
}
@ -89,6 +88,7 @@ int snd_ak4113_create(struct snd_card *card, ak4113_read_t *read,
chip->write = write;
chip->private_data = private_data;
INIT_DELAYED_WORK(&chip->work, ak4113_stats);
atomic_set(&chip->wq_processing, 0);
for (reg = 0; reg < AK4113_WRITABLE_REGS ; reg++)
chip->regmap[reg] = pgm[reg];
@ -139,13 +139,11 @@ static void ak4113_init_regs(struct ak4113 *chip)
void snd_ak4113_reinit(struct ak4113 *chip)
{
chip->init = 1;
mb();
flush_delayed_work(&chip->work);
if (atomic_inc_return(&chip->wq_processing) == 1)
cancel_delayed_work_sync(&chip->work);
ak4113_init_regs(chip);
/* bring up statistics / event queing */
chip->init = 0;
if (chip->kctls[0])
if (atomic_dec_and_test(&chip->wq_processing))
schedule_delayed_work(&chip->work, HZ / 10);
}
EXPORT_SYMBOL_GPL(snd_ak4113_reinit);
@ -632,8 +630,9 @@ static void ak4113_stats(struct work_struct *work)
{
struct ak4113 *chip = container_of(work, struct ak4113, work.work);
if (!chip->init)
if (atomic_inc_return(&chip->wq_processing) == 1)
snd_ak4113_check_rate_and_errors(chip, chip->check_flags);
schedule_delayed_work(&chip->work, HZ / 10);
if (atomic_dec_and_test(&chip->wq_processing))
schedule_delayed_work(&chip->work, HZ / 10);
}

18
sound/i2c/other/ak4114.c
View File

@ -66,8 +66,7 @@ static void reg_dump(struct ak4114 *ak4114)
static void snd_ak4114_free(struct ak4114 *chip)
{
chip->init = 1; /* don't schedule new work */
mb();
atomic_inc(&chip->wq_processing); /* don't schedule new work */
cancel_delayed_work_sync(&chip->work);
kfree(chip);
}
@ -100,6 +99,7 @@ int snd_ak4114_create(struct snd_card *card,
chip->write = write;
chip->private_data = private_data;
INIT_DELAYED_WORK(&chip->work, ak4114_stats);
atomic_set(&chip->wq_processing, 0);
for (reg = 0; reg < 6; reg++)
chip->regmap[reg] = pgm[reg];
@ -152,13 +152,11 @@ static void ak4114_init_regs(struct ak4114 *chip)
void snd_ak4114_reinit(struct ak4114 *chip)
{
chip->init = 1;
mb();
flush_delayed_work(&chip->work);
if (atomic_inc_return(&chip->wq_processing) == 1)
cancel_delayed_work_sync(&chip->work);
ak4114_init_regs(chip);
/* bring up statistics / event queing */
chip->init = 0;
if (chip->kctls[0])
if (atomic_dec_and_test(&chip->wq_processing))
schedule_delayed_work(&chip->work, HZ / 10);
}
@ -612,10 +610,10 @@ static void ak4114_stats(struct work_struct *work)
{
struct ak4114 *chip = container_of(work, struct ak4114, work.work);
if (!chip->init)
if (atomic_inc_return(&chip->wq_processing) == 1)
snd_ak4114_check_rate_and_errors(chip, chip->check_flags);
schedule_delayed_work(&chip->work, HZ / 10);
if (atomic_dec_and_test(&chip->wq_processing))
schedule_delayed_work(&chip->work, HZ / 10);
}
EXPORT_SYMBOL(snd_ak4114_create);