1 files changed, 29 insertions, 3 deletions

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 95fb4939c675..cc1faa31d124 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -71,6 +71,11 @@ static void uart_change_pm(struct uart_state *state, int pm_state);
 void uart_write_wakeup(struct uart_port *port)
 {
         struct uart_info *info = port->info;
+        /*
+         * This means you called this function _after_ the port was
+         * closed.  No cookie for you.
+         */
+        BUG_ON(!info);
         tasklet_schedule(&info->tlet);
 }
 
@@ -471,14 +476,26 @@ static void uart_flush_chars(struct tty_struct *tty)
 }
 
 static int
-uart_write(struct tty_struct *tty, const unsigned char * buf, int count)
+uart_write(struct tty_struct *tty, const unsigned char *buf, int count)
 {
         struct uart_state *state = tty->driver_data;
-        struct uart_port *port = state->port;
-        struct circ_buf *circ = &state->info->xmit;
+        struct uart_port *port;
+        struct circ_buf *circ;
         unsigned long flags;
         int c, ret = 0;
 
+        /*
+         * This means you called this function _after_ the port was
+         * closed.  No cookie for you.
+         */
+        if (!state || !state->info) {
+                WARN_ON(1);
+                return -EL3HLT;
+        }
+
+        port = state->port;
+        circ = &state->info->xmit;
+
         if (!circ->buf)
                 return 0;
 
@@ -521,6 +538,15 @@ static void uart_flush_buffer(struct tty_struct *tty)
         struct uart_port *port = state->port;
         unsigned long flags;
 
+        /*
+         * This means you called this function _after_ the port was
+         * closed.  No cookie for you.
+         */
+        if (!state || !state->info) {
+                WARN_ON(1);
+                return;
+        }
+
         DPRINTK("uart_flush_buffer(%d) called\n", tty->index);
 
         spin_lock_irqsave(&port->lock, flags);