w1: do not unlock unheld list_mutex in __w1_remove_master_device()

w1_process_callbacks() expects to be called with dev->list_mutex held,
but it is the fact only in w1_process(). __w1_remove_master_device()
calls w1_process_callbacks() after it releases list_mutex.

The patch fixes __w1_remove_master_device() to acquire list_mutex
for w1_process_callbacks().

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

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Acked-by: David Fries <david@fries.net>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Cc: stable <stable@vger.kernel.org> # 3.15
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/w1/w1_int.c b/drivers/w1/w1_int.c
index 9b084db..728039d2 100644
--- a/drivers/w1/w1_int.c
+++ b/drivers/w1/w1_int.c
@@ -219,9 +219,13 @@
 
 		if (msleep_interruptible(1000))
 			flush_signals(current);
+		mutex_lock(&dev->list_mutex);
 		w1_process_callbacks(dev);
+		mutex_unlock(&dev->list_mutex);
 	}
+	mutex_lock(&dev->list_mutex);
 	w1_process_callbacks(dev);
+	mutex_unlock(&dev->list_mutex);
 
 	memset(&msg, 0, sizeof(msg));
 	msg.id.mst.id = dev->id;