[media] lirc_zilog: Convert the instance open count to an atomic_t

The open count is simply used for deciding if the Rx polling thread
needs to poll the IR chip for userspace.  Simplify the manipulation
of the open count by using an atomic_t and not requiring a lock
The polling thread errantly didn't try to take the lock anyway.
Signed-off-by: Andy Walls <awalls@md.metrocast.net>
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/staging/lirc/lirc_zilog.c

@@ -94,7 +94,7 @@ struct IR {
 	struct lirc_driver l;
 
 	struct mutex ir_lock;
-	int open;
+	atomic_t open_count;
 
 	struct i2c_adapter *adapter;
 	struct IR_rx *rx;
@@ -279,7 +279,7 @@ static int lirc_thread(void *arg)
 		set_current_state(TASK_INTERRUPTIBLE);
 
 		/* if device not opened, we can sleep half a second */
-		if (!ir->open) {
+		if (atomic_read(&ir->open_count) == 0) {
 			schedule_timeout(HZ/2);
 			continue;
 		}
@@ -1094,10 +1094,7 @@ static int open(struct inode *node, struct file *filep)
 	if (ir == NULL)
 		return -ENODEV;
 
-	/* increment in use count */
-	mutex_lock(&ir->ir_lock);
-	++ir->open;
-	mutex_unlock(&ir->ir_lock);
+	atomic_inc(&ir->open_count);
 
 	/* stash our IR struct */
 	filep->private_data = ir;
@@ -1115,10 +1112,7 @@ static int close(struct inode *node, struct file *filep)
 		return -ENODEV;
 	}
 
-	/* decrement in use count */
-	mutex_lock(&ir->ir_lock);
-	--ir->open;
-	mutex_unlock(&ir->ir_lock);
+	atomic_dec(&ir->open_count);
 
 	return 0;
 }
@@ -1294,6 +1288,7 @@ static int ir_probe(struct i2c_client *client, const struct i2c_device_id *id)
 
 		ir->adapter = adap;
 		mutex_init(&ir->ir_lock);
+		atomic_set(&ir->open_count, 0);
 
 		/* set lirc_dev stuff */
 		memcpy(&ir->l, &lirc_template, sizeof(struct lirc_driver));