[PATCH] remove TTY_DONT_FLIP

Remove TTY_DONT_FLIP tty flag.  This flag was introduced in 2.1.X kernels
to prevent the N_TTY line discipline functions read_chan() and
n_tty_receive_buf() from running at the same time.  2.2.15 introduced
tty->read_lock to protect access to the N_TTY read buffer, which is the
only state requiring protection between these two functions.

The current TTY_DONT_FLIP implementation is broken for SMP, and is not
universally honored by drivers that send data directly to the line
discipline receive_buf function.

Because TTY_DONT_FLIP is not necessary, is broken in implementation, and is
not universally honored, it is removed.

Signed-off-by: Paul Fulghum <paulkf@microgate.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 0 insertions, 1 deletions

diff --git a/include/linux/tty.h b/include/linux/tty.h
index cb35ca50a0a6..341cc4552c00 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -259,7 +259,6 @@ struct tty_struct {
 #define TTY_DO_WRITE_WAKEUP     5       /* Call write_wakeup after queuing new */
 #define TTY_PUSH                6       /* n_tty private */
 #define TTY_CLOSING             7       /* ->close() in progress */
-#define TTY_DONT_FLIP           8       /* Defer buffer flip */
 #define TTY_LDISC               9       /* Line discipline attached */
 #define TTY_HW_COOK_OUT         14      /* Hardware can do output cooking */
 #define TTY_HW_COOK_IN          15      /* Hardware can do input cooking */