+static int trust_exclusive_open(struct inode *inode, struct file *file)
+{
+ return test_and_set_bit(0, &in_use) ? -EBUSY : 0;
+}
+
+static int trust_exclusive_release(struct inode *inode, struct file *file)
+{
+ clear_bit(0, &in_use);
+ return 0;
+}
+