tty: serial_core: add tty NULL check to uart_tx_stopped

Commit 761ed4a94582 ("tty: serial_core: convert uart_close to use
tty_port_close") created a case where a port used for a console does not
get shutdown on tty closing. Then a call to uart_tx_stopped() segfaults
because the tty is NULL. This could be fixed to restore old behavior,
but we also want to allow tty_ports to work without a tty attached. So
this change to allow a NULL tty_struct is needed either way.

Fixes: 761ed4a94582 ("tty: serial_core: convert uart_close to use tty_port_close")
Reported-by: kernel test robot <xiaolong.ye@intel.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index cdba6f144f72bda13b3a0b6e8e97ac5da939b863..378d80a8dd43abf302db1820494134978ba91b3d 100644 (file)
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -412,7 +412,7 @@ int uart_resume_port(struct uart_driver *reg, struct uart_port *port);
 static inline int uart_tx_stopped(struct uart_port *port)
 {
        struct tty_struct *tty = port->state->port.tty;
-       if (tty->stopped || port->hw_stopped)
+       if ((tty && tty->stopped) || port->hw_stopped)
                return 1;
        return 0;
 }