ALSA: ak411x: Fix stall in work callback
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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/i2c/other/ak4114.c b/sound/i2c/other/ak4114.c
index c7f5633..b70e6ec 100644
--- a/sound/i2c/other/ak4114.c
+++ b/sound/i2c/other/ak4114.c
@@ -66,8 +66,7 @@
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 @@
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 @@
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 @@
{
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);