[PATCH v3 2/2] Bluetooth: hci_ldisc: Add NULL check for tiocmget() and tiocmset() in hci_uart_set_flow_control()

[Myungho Jung]

tiocmget() or tiocmset() operations are optional. Just return from
hci_uart_set_flow_control() if tiocmget() or tiocmset() operation is
NULL.

Fixes: 2a973dfada2b ("hci_uart: Add new line discipline enhancements")
Cc: <stable@xxxxxxxxxxxxxxx> # 4.2
Signed-off-by: Myungho Jung <mhjungk@xxxxxxxxx>
---
Changes in v2:
  - Remove braces in if statment

Changes in v3:
  - Split into 2 patches
  - Add stable CC and fixes tags

 drivers/bluetooth/hci_ldisc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index fbf7b4df23ab..cb31c2d8d826 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -314,6 +314,10 @@ void hci_uart_set_flow_control(struct hci_uart *hu, bool enable)
 		return;
 	}
 
+	/* tiocmget() and tiocmset() operations are optional */
+	if (!tty->driver->ops->tiocmget || !tty->driver->ops->tiocmset)
+		return;
+
 	if (enable) {
 		/* Disable hardware flow control */
 		ktermios = tty->termios;
-- 
2.17.1