[PATCH 4/9] w1: ds28e04: use the bus mutex to talk on the bus

[Greg Kroah-Hartman]

From: Josef Bacik <josef@xxxxxxxxxxxxxx>

Since commit b02f8bede217 ("W1: split master mutex to avoid deadlocks.")
the slave drivers serialise their accesses to the bus with bus_mutex.
This driver, which was merged shortly afterwards, takes the mutex of the
master in the callbacks of its eeprom and pio files instead.

That mutex is held while a slave which has disappeared from the bus is
removed, which waits for the sysfs callbacks of the slave to return.  A
callback which is waiting for the mutex at that moment never does: both
tasks are stuck, and with them the thread of the bus master.

Besides, it does not keep the other slave drivers off the bus, so that two
transactions can get mixed up on the wire.

Fixes: fbf7f7b4e2ae ("w1: Add 1-wire slave device driver for DS28E04-100")
Cc: stable <stable@xxxxxxxxxx>
Signed-off-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/w1/slaves/w1_ds28e04.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/w1/slaves/w1_ds28e04.c b/drivers/w1/slaves/w1_ds28e04.c
index 3b3c0789e1ad..30fb8415b659 100644
--- a/drivers/w1/slaves/w1_ds28e04.c
+++ b/drivers/w1/slaves/w1_ds28e04.c
@@ -123,7 +123,7 @@ static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
 	if (count == 0)
 		return 0;
 
-	mutex_lock(&sl->master->mutex);
+	mutex_lock(&sl->master->bus_mutex);
 
 	if (w1_enable_crccheck) {
 		min_page = (off >> W1_PAGE_BITS);
@@ -140,7 +140,7 @@ static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
 	}
 
 out_up:
-	mutex_unlock(&sl->master->mutex);
+	mutex_unlock(&sl->master->bus_mutex);
 
 	return count;
 }
@@ -253,7 +253,7 @@ static ssize_t eeprom_write(struct file *filp, struct kobject *kobj,
 		}
 	}
 
-	mutex_lock(&sl->master->mutex);
+	mutex_lock(&sl->master->bus_mutex);
 
 	/* Can only write data to one page at a time */
 	idx = 0;
@@ -271,7 +271,7 @@ static ssize_t eeprom_write(struct file *filp, struct kobject *kobj,
 	}
 
 out_up:
-	mutex_unlock(&sl->master->mutex);
+	mutex_unlock(&sl->master->bus_mutex);
 
 	return count;
 }
@@ -290,9 +290,9 @@ static ssize_t pio_read(struct file *filp, struct kobject *kobj,
 	if (off != 0 || count != 1 || buf == NULL)
 		return -EINVAL;
 
-	mutex_lock(&sl->master->mutex);
+	mutex_lock(&sl->master->bus_mutex);
 	ret = w1_f1C_read(sl, W1_1C_REG_LOGIC_STATE, count, buf);
-	mutex_unlock(&sl->master->mutex);
+	mutex_unlock(&sl->master->bus_mutex);
 
 	return ret;
 }
@@ -310,11 +310,11 @@ static ssize_t pio_write(struct file *filp, struct kobject *kobj,
 	if (off != 0 || count != 1 || buf == NULL)
 		return -EINVAL;
 
-	mutex_lock(&sl->master->mutex);
+	mutex_lock(&sl->master->bus_mutex);
 
 	/* Write the PIO data */
 	if (w1_reset_select_slave(sl)) {
-		mutex_unlock(&sl->master->mutex);
+		mutex_unlock(&sl->master->bus_mutex);
 		return -1;
 	}
 
@@ -328,7 +328,7 @@ static ssize_t pio_write(struct file *filp, struct kobject *kobj,
 
 	w1_read_block(sl->master, &ack, sizeof(ack));
 
-	mutex_unlock(&sl->master->mutex);
+	mutex_unlock(&sl->master->bus_mutex);
 
 	/* check for acknowledgement */
 	if (ack != 0xAA)

-- 
2.56.0