max3110: Fix up port->tty backreferencing

We want to keep refcounts properly on this against hangup.

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

1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/tty/serial/mrst_max3110.c b/drivers/tty/serial/mrst_max3110.c
index 42aa43934b20..1aa2c3cd2146 100644
--- a/drivers/tty/serial/mrst_max3110.c
+++ b/drivers/tty/serial/mrst_max3110.c
@@ -347,7 +347,7 @@ receive_chars(struct uart_max3110 *max, unsigned short *str, int len)
         if (!port->state)
                 return 0;
 
-        tty = port->state->port.tty;
+        tty = tty_port_tty_get(&port->state->port);
         if (!tty)
                 return 0;
 
@@ -364,8 +364,10 @@ receive_chars(struct uart_max3110 *max, unsigned short *str, int len)
                 }
         }
 
-        if (!w)
+        if (!w) {
+                tty_kref_put(tty);
                 return 0;
+        }
 
         for (r = 0; w; r += usable, w -= usable) {
                 usable = tty_buffer_request_room(tty, w);
@@ -375,6 +377,7 @@ receive_chars(struct uart_max3110 *max, unsigned short *str, int len)
                 }
         }
         tty_flip_buffer_push(tty);
+        tty_kref_put(tty);
 
         return r;
 }