tty: serial - fix tty referencing in set_ldisc

Pass down the ldisc number so that the drivers don't have to peek into the
tty object themselves. This lets us get rid of another case of back referencing
port to tty which we don't want (because of races versus hangup/close).

Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 4 insertions, 7 deletions

diff --git a/drivers/serial/bfin_5xx.c b/drivers/serial/bfin_5xx.c
index 511cbf68787..a9eff2b18ea 100644
--- a/drivers/serial/bfin_5xx.c
+++ b/drivers/serial/bfin_5xx.c
@@ -957,15 +957,12 @@ bfin_serial_verify_port(struct uart_port *port, struct serial_struct *ser)
  * Enable the IrDA function if tty->ldisc.num is N_IRDA.
  * In other cases, disable IrDA function.
  */
-static void bfin_serial_set_ldisc(struct uart_port *port)
+static void bfin_serial_set_ldisc(struct uart_port *port, int ld)
 {
         int line = port->line;
         unsigned short val;
 
-        if (line >= port->state->port.tty->driver->num)
-                return;
-
-        switch (port->state->port.tty->termios->c_line) {
+        switch (ld) {
         case N_IRDA:
                 val = UART_GET_GCTL(&bfin_serial_ports[line]);
                 val |= (IREN | RPOLC);
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 12ee7e0f99c..570dca2935e 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -1194,7 +1194,7 @@ static void uart_set_ldisc(struct tty_struct *tty)
         struct uart_port *uport = state->uart_port;
 
         if (uport->ops->set_ldisc)
-                uport->ops->set_ldisc(uport);
+                uport->ops->set_ldisc(uport, tty->termios->c_line);
 }
 
 static void uart_set_termios(struct tty_struct *tty,
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index f10db6e5f3b..32928161fab 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -220,7 +220,7 @@ struct uart_ops {
         void            (*flush_buffer)(struct uart_port *);
         void            (*set_termios)(struct uart_port *, struct ktermios *new,
                                        struct ktermios *old);
-        void            (*set_ldisc)(struct uart_port *);
+        void            (*set_ldisc)(struct uart_port *, int new);
         void            (*pm)(struct uart_port *, unsigned int state,
                               unsigned int oldstate);
         int             (*set_wake)(struct uart_port *, unsigned int state);