[PATCH] Fix tty layer DoS and comment relevant code

Unlike the other tty comment patch this one has code changes.  Specifically
it limits the queue size for a tty to 64K characters (128Kbytes) worst case
even if the tty is ignoring tty->throttle.  This is because certain drivers
don't honour the throttle value correctly, although it is a useful
safeguard anyway.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/tty.h b/include/linux/tty.h
index e421d5e34818..04827ca65781 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -59,6 +59,7 @@ struct tty_bufhead {
         struct tty_buffer *head;        /* Queue head */
         struct tty_buffer *tail;        /* Active buffer */
         struct tty_buffer *free;        /* Free queue head */
+        int memory_used;                /* Buffer space used excluding free queue */
 };
 /*
  * The pty uses char_buf and flag_buf as a contiguous buffer