n_tty: Simplify throttle threshold calculation

The adjustments performed by receive_room() are to ensure a line
termination can always be written to the read buffer. However,
these adjustments are irrelevant to the throttle threshold (because
the threshold < buffer limit).

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index d4b14c30794e2ec78c6f83c57376a17f4e4fdda7..7efabc4673b6a79d8822264a02a4c8afd09a91d8 100644 (file)
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -262,7 +262,7 @@ static void n_tty_check_throttle(struct tty_struct *tty)
        while (1) {
                int throttled;
                tty_set_flow_change(tty, TTY_THROTTLE_SAFE);
-               if (receive_room(tty) >= TTY_THRESHOLD_THROTTLE)
+               if (N_TTY_BUF_SIZE - read_cnt(ldata) >= TTY_THRESHOLD_THROTTLE)
                        break;
                throttled = tty_throttle_safe(tty);
                if (!throttled)