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Commit f488d9fc authored by Hans-Christian Egtvedt's avatar Hans-Christian Egtvedt Committed by Jaroslav Kysela
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[ALSA] at73c213: replace spinlock in mixer functions with a mutex 



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: default avatarHans-Christian Egtvedt <hcegtvedt@atmel.com>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarJaroslav Kysela <perex@perex.cz>
parent ac3e3741

sound/spi/at73c213.c

+19 −15
Original line number Diff line number Diff line
@@ -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;