2 files changed, 10 insertions, 2 deletions

diff --git a/include/linux/tty.h b/include/linux/tty.h
index 38fcc0574ba9..ad98b4376968 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -39,10 +39,14 @@ struct tty_buffer {
         int size;
         int commit;
         int read;
+        int flags;
         /* Data points here */
         unsigned long data[0];
 };
 
+/* Values for .flags field of tty_buffer */
+#define TTYB_NORMAL     1       /* buffer has no flags buffer */
+
 static inline unsigned char *char_buf_ptr(struct tty_buffer *b, int ofs)
 {
         return ((unsigned char *)b->data) + ofs;
diff --git a/include/linux/tty_flip.h b/include/linux/tty_flip.h
index 3f821e98af0f..c28dd523f96e 100644
--- a/include/linux/tty_flip.h
+++ b/include/linux/tty_flip.h
@@ -17,8 +17,12 @@ static inline int tty_insert_flip_char(struct tty_port *port,
                                         unsigned char ch, char flag)
 {
         struct tty_buffer *tb = port->buf.tail;
-        if (tb && tb->used < tb->size) {
-                *flag_buf_ptr(tb, tb->used) = flag;
+        int change;
+
+        change = (tb->flags & TTYB_NORMAL) && (flag != TTY_NORMAL);
+        if (!change && tb->used < tb->size) {
+                if (~tb->flags & TTYB_NORMAL)
+                        *flag_buf_ptr(tb, tb->used) = flag;
                 *char_buf_ptr(tb, tb->used++) = ch;
                 return 1;
         }