[PATCH 5/9] w1: ds2805: use the bus mutex to talk on the bus

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Josef Bacik <josef@toxicpanda.com>

Since commit b02f8bede217 ("W1: split master mutex to avoid deadlocks.")
the slave drivers serialise their accesses to the bus with bus_mutex.
This driver takes the mutex of the master in the callbacks of its eeprom
file 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: f6887531c0c6 ("drivers: w1: Add 1w slave driver for DS28E05 EEPROM")
Cc: stable <stable@kernel.org>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/w1/slaves/w1_ds2805.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/w1/slaves/w1_ds2805.c b/drivers/w1/slaves/w1_ds2805.c
index 9c86b7985d0b..bfcc02ecbdb9 100644
--- a/drivers/w1/slaves/w1_ds2805.c
+++ b/drivers/w1/slaves/w1_ds2805.c
@@ -102,7 +102,7 @@ static ssize_t w1_f0d_read_bin(struct file *filp, struct kobject *kobj,
 	if (count == 0)
 		return 0;
 
-	mutex_lock(&sl->master->mutex);
+	mutex_lock(&sl->master->bus_mutex);
 
 	/* read directly from the EEPROM in chunks of W1_F0D_READ_MAXLEN */
 	while (todo > 0) {
@@ -123,7 +123,7 @@ static ssize_t w1_f0d_read_bin(struct file *filp, struct kobject *kobj,
 		off += W1_F0D_READ_MAXLEN;
 	}
 
-	mutex_unlock(&sl->master->mutex);
+	mutex_unlock(&sl->master->bus_mutex);
 
 	return count;
 }
@@ -211,7 +211,7 @@ static ssize_t w1_f0d_write_bin(struct file *filp, struct kobject *kobj,
 	if (count == 0)
 		return 0;
 
-	mutex_lock(&sl->master->mutex);
+	mutex_lock(&sl->master->bus_mutex);
 
 	/* Can only write data in blocks of the size of the scratchpad */
 	addr = off;
@@ -256,7 +256,7 @@ static ssize_t w1_f0d_write_bin(struct file *filp, struct kobject *kobj,
 	}
 
 out_up:
-	mutex_unlock(&sl->master->mutex);
+	mutex_unlock(&sl->master->bus_mutex);
 
 	return count;
 }

-- 
2.56.0