w1_bq27000: Only one thread can access the bq27000 at a time.

If multiple threads try, they trip over each other badly.

Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/w1/slaves/w1_bq27000.c b/drivers/w1/slaves/w1_bq27000.c
index 6ae60aa1315b..52ad812fa1e7 100644
--- a/drivers/w1/slaves/w1_bq27000.c
+++ b/drivers/w1/slaves/w1_bq27000.c
@@ -31,8 +31,10 @@ static int w1_bq27000_read(struct device *dev, unsigned int reg)
         u8 val;
         struct w1_slave *sl = container_of(dev->parent, struct w1_slave, dev);
 
+        mutex_lock(&sl->master->mutex);
         w1_write_8(sl->master, HDQ_CMD_READ | reg);
         val = w1_read_8(sl->master);
+        mutex_unlock(&sl->master->mutex);
 
         return val;
 }