target/linux/brcm2708/patches-4.4/0202-serial-Take-care-starting-a-hung-up-tty-s-port.patch

   1 From abd2da573a492fe1c64fa7a269b121046b2f3acf Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.org>
   3 Date: Wed, 9 Mar 2016 13:28:24 +0000
   4 Subject: [PATCH 202/304] serial: Take care starting a hung-up tty's port
   5
   6 tty_port_hangup sets a port's tty field to NULL (holding the port lock),
   7 but uart_tx_stopped, called from __uart_start (with the port lock),
   8 uses the tty field without checking for NULL.
   9
  10 Change uart_tx_stopped to treat a NULL tty field as another stopped
  11 indication.
  12
  13 Signed-off-by: Phil Elwell <phil@raspberrypi.org>
  14 ---
  15  include/linux/serial_core.h | 2 +-
  16  1 file changed, 1 insertion(+), 1 deletion(-)
  17
  18 --- a/include/linux/serial_core.h
  19 +++ b/include/linux/serial_core.h
  20 @@ -397,7 +397,7 @@ int uart_resume_port(struct uart_driver
  21  static inline int uart_tx_stopped(struct uart_port *port)
  22  {
  23         struct tty_struct *tty = port->state->port.tty;
  24 -       if (tty->stopped || port->hw_stopped)
  25 +       if (!tty || tty->stopped || port->hw_stopped)
  26                 return 1;
  27         return 0;
  28  }