Commit f53459c0 authored by Alexey Khoroshilov's avatar Alexey Khoroshilov Committed by Greg Kroah-Hartman
Browse files

w1: keep balance of mutex locks and refcnts 



w1_therm_eeprom() and w1_DS18B20_precision() decrement THERM_REFCNT
on error paths, while they did not increment it yet.

read_therm() unlocks bus mutex on some error paths,
while it is not acquired.

The patch makes sure all the functions keep the balance in usage of
the mutex and the THERM_REFCNT.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: default avatarAlexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d4035a8c

drivers/w1/slaves/w1_therm.c

+31 −28
Original line number Diff line number Diff line
@@ -268,17 +268,18 @@ static inline int w1_therm_eeprom(struct device *device) 
	int ret, max_trying = 10;

	u8 *family_data = sl->family_data;



	ret = mutex_lock_interruptible(&dev->bus_mutex);

	if (ret != 0)

		goto post_unlock;



	if (!sl->family_data) {

		ret = -ENODEV;

		goto pre_unlock;

		goto error;

	}



	/* prevent the slave from going away in sleep */

	atomic_inc(THERM_REFCNT(family_data));



	ret = mutex_lock_interruptible(&dev->bus_mutex);

	if (ret != 0)

		goto dec_refcnt;



	memset(rom, 0, sizeof(rom));



	while (max_trying--) {
@@ -306,17 +307,17 @@ static inline int w1_therm_eeprom(struct device *device) 
				sleep_rem = msleep_interruptible(tm);

				if (sleep_rem != 0) {

					ret = -EINTR;

					goto post_unlock;

					goto dec_refcnt;

				}



				ret = mutex_lock_interruptible(&dev->bus_mutex);

				if (ret != 0)

					goto post_unlock;

					goto dec_refcnt;

			} else if (!w1_strong_pullup) {

				sleep_rem = msleep_interruptible(tm);

				if (sleep_rem != 0) {

					ret = -EINTR;

					goto pre_unlock;

					goto mt_unlock;

				}

			}
@@ -324,11 +325,11 @@ static inline int w1_therm_eeprom(struct device *device) 
		}

	}



pre_unlock:

mt_unlock:

	mutex_unlock(&dev->bus_mutex);



post_unlock:

dec_refcnt:

	atomic_dec(THERM_REFCNT(family_data));

error:

	return ret;

}
@@ -350,20 +351,22 @@ static inline int w1_DS18B20_precision(struct device *device, int val) 


	if (val > 12 || val < 9) {

		pr_warn("Unsupported precision\n");

		return -1;

		ret = -EINVAL;

		goto error;

	}



	ret = mutex_lock_interruptible(&dev->bus_mutex);

	if (ret != 0)

		goto post_unlock;



	if (!sl->family_data) {

		ret = -ENODEV;

		goto pre_unlock;

		goto error;

	}



	/* prevent the slave from going away in sleep */

	atomic_inc(THERM_REFCNT(family_data));



	ret = mutex_lock_interruptible(&dev->bus_mutex);

	if (ret != 0)

		goto dec_refcnt;



	memset(rom, 0, sizeof(rom));



	/* translate precision to bitmask (see datasheet page 9) */
@@ -411,11 +414,10 @@ static inline int w1_DS18B20_precision(struct device *device, int val) 
		}

	}



pre_unlock:

	mutex_unlock(&dev->bus_mutex);



post_unlock:

dec_refcnt:

	atomic_dec(THERM_REFCNT(family_data));

error:

	return ret;

}
@@ -490,17 +492,18 @@ static ssize_t read_therm(struct device *device, 
	int ret, max_trying = 10;

	u8 *family_data = sl->family_data;



	ret = mutex_lock_interruptible(&dev->bus_mutex);

	if (ret != 0)

		goto error;



	if (!family_data) {

		ret = -ENODEV;

		goto mt_unlock;

		goto error;

	}



	/* prevent the slave from going away in sleep */

	atomic_inc(THERM_REFCNT(family_data));



	ret = mutex_lock_interruptible(&dev->bus_mutex);

	if (ret != 0)

		goto dec_refcnt;



	memset(info->rom, 0, sizeof(info->rom));



	while (max_trying--) {
@@ -542,7 +545,7 @@ static ssize_t read_therm(struct device *device, 
				sleep_rem = msleep_interruptible(tm);

				if (sleep_rem != 0) {

					ret = -EINTR;

					goto dec_refcnt;

					goto mt_unlock;

				}

			}
@@ -567,10 +570,10 @@ static ssize_t read_therm(struct device *device, 
			break;

	}



dec_refcnt:

	atomic_dec(THERM_REFCNT(family_data));

mt_unlock:

	mutex_unlock(&dev->bus_mutex);

dec_refcnt:

	atomic_dec(THERM_REFCNT(family_data));

error:

	return ret;

}

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