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[ALSA] at73c213: replace spinlock in mixer functions with a mutex

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This patch fixes the locking bug in the at73c213 SPI sound driver. This bug was
triggered because spinlocks were wrapped around the spi_sync call which might
sleep. The fix was to add a mutex to the sound driver and replace the spinlocks
in the mixer functions with mutex lock/unlock.
Tested on STK1000/STK1002.

Signed-off-by: Hans-Christian Egtvedt <hcegtvedt@atmel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
This commit is contained in:
Hans-Christian Egtvedt 2007-12-17 17:30:06 +01:00 committed by Jaroslav Kysela
parent ac3e37412c
commit f488d9fcc8
1 changed files with 19 additions and 15 deletions
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34
sound/spi/at73c213.c
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@ -18,6 +18,7 @@
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/io.h>
@ -76,8 +77,10 @@ struct snd_at73c213 {
u8 spi_rbuffer[2];
/* Image of the SPI registers in AT73C213. */
u8 reg_image[18];
/* Protect registers against concurrent access. */
/* Protect SSC registers against concurrent access. */
spinlock_t lock;
/* Protect mixer registers against concurrent access. */
struct mutex mixer_lock;
};
#define get_chip(card) ((struct snd_at73c213 *)card->private_data)
@ -398,7 +401,7 @@ static int snd_at73c213_mono_get(struct snd_kcontrol *kcontrol,
int mask = (kcontrol->private_value >> 16) & 0xff;
int invert = (kcontrol->private_value >> 24) & 0xff;
spin_lock_irq(&chip->lock);
mutex_lock(&chip->mixer_lock);
ucontrol->value.integer.value[0] =
(chip->reg_image[reg] >> shift) & mask;
@ -407,7 +410,7 @@ static int snd_at73c213_mono_get(struct snd_kcontrol *kcontrol,
ucontrol->value.integer.value[0] =
mask - ucontrol->value.integer.value[0];
spin_unlock_irq(&chip->lock);
mutex_unlock(&chip->mixer_lock);
return 0;
}
@ -428,13 +431,13 @@ static int snd_at73c213_mono_put(struct snd_kcontrol *kcontrol,
val = mask - val;
val <<= shift;
spin_lock_irq(&chip->lock);
mutex_lock(&chip->mixer_lock);
val = (chip->reg_image[reg] & ~(mask << shift)) | val;
change = val != chip->reg_image[reg];
retval = snd_at73c213_write_reg(chip, reg, val);
spin_unlock_irq(&chip->lock);
mutex_unlock(&chip->mixer_lock);
if (retval)
return retval;
@ -470,7 +473,7 @@ static int snd_at73c213_stereo_get(struct snd_kcontrol *kcontrol,
int mask = (kcontrol->private_value >> 24) & 0xff;
int invert = (kcontrol->private_value >> 22) & 1;
spin_lock_irq(&chip->lock);
mutex_lock(&chip->mixer_lock);
ucontrol->value.integer.value[0] =
(chip->reg_image[left_reg] >> shift_left) & mask;
@ -484,7 +487,7 @@ static int snd_at73c213_stereo_get(struct snd_kcontrol *kcontrol,
mask - ucontrol->value.integer.value[1];
}
spin_unlock_irq(&chip->lock);
mutex_unlock(&chip->mixer_lock);
return 0;
}
@ -511,7 +514,7 @@ static int snd_at73c213_stereo_put(struct snd_kcontrol *kcontrol,
val1 <<= shift_left;
val2 <<= shift_right;
spin_lock_irq(&chip->lock);
mutex_lock(&chip->mixer_lock);
val1 = (chip->reg_image[left_reg] & ~(mask << shift_left)) | val1;
val2 = (chip->reg_image[right_reg] & ~(mask << shift_right)) | val2;
@ -519,16 +522,16 @@ static int snd_at73c213_stereo_put(struct snd_kcontrol *kcontrol,
|| val2 != chip->reg_image[right_reg];
retval = snd_at73c213_write_reg(chip, left_reg, val1);
if (retval) {
spin_unlock_irq(&chip->lock);
mutex_unlock(&chip->mixer_lock);
goto out;
}
retval = snd_at73c213_write_reg(chip, right_reg, val2);
if (retval) {
spin_unlock_irq(&chip->lock);
mutex_unlock(&chip->mixer_lock);
goto out;
}
spin_unlock_irq(&chip->lock);
mutex_unlock(&chip->mixer_lock);
return change;
@ -546,7 +549,7 @@ static int snd_at73c213_mono_switch_get(struct snd_kcontrol *kcontrol,
int shift = (kcontrol->private_value >> 8) & 0xff;
int invert = (kcontrol->private_value >> 24) & 0xff;
spin_lock_irq(&chip->lock);
mutex_lock(&chip->mixer_lock);
ucontrol->value.integer.value[0] =
(chip->reg_image[reg] >> shift) & 0x01;
@ -555,7 +558,7 @@ static int snd_at73c213_mono_switch_get(struct snd_kcontrol *kcontrol,
ucontrol->value.integer.value[0] =
0x01 - ucontrol->value.integer.value[0];
spin_unlock_irq(&chip->lock);
mutex_unlock(&chip->mixer_lock);
return 0;
}
@ -580,14 +583,14 @@ static int snd_at73c213_mono_switch_put(struct snd_kcontrol *kcontrol,
val = mask - val;
val <<= shift;
spin_lock_irq(&chip->lock);
mutex_lock(&chip->mixer_lock);
val |= (chip->reg_image[reg] & ~(mask << shift));
change = val != chip->reg_image[reg];
retval = snd_at73c213_write_reg(chip, reg, val);
spin_unlock_irq(&chip->lock);
mutex_unlock(&chip->mixer_lock);
if (retval)
return retval;
@ -884,6 +887,7 @@ static int __devinit snd_at73c213_dev_init(struct snd_card *card,
return irq;
spin_lock_init(&chip->lock);
mutex_init(&chip->mixer_lock);
chip->card = card;
chip->irq = -1;