tty: Add diagnostic for halted line discipline
Flip buffer work must not be scheduled by the line discipline
after the line discipline has been halted; issue warning.
Note: drivers can still schedule flip buffer work.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index d794087..c641321 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -375,6 +375,7 @@
void tty_ldisc_enable(struct tty_struct *tty)
{
+ clear_bit(TTY_LDISC_HALTED, &tty->flags);
set_bit(TTY_LDISC, &tty->flags);
clear_bit(TTY_LDISC_CHANGING, &tty->flags);
wake_up(&tty_ldisc_wait);
@@ -513,8 +514,11 @@
static int tty_ldisc_halt(struct tty_struct *tty)
{
+ int scheduled;
clear_bit(TTY_LDISC, &tty->flags);
- return cancel_work_sync(&tty->port->buf.work);
+ scheduled = cancel_work_sync(&tty->port->buf.work);
+ set_bit(TTY_LDISC_HALTED, &tty->flags);
+ return scheduled;
}
/**
@@ -820,6 +824,7 @@
clear_bit(TTY_LDISC, &tty->flags);
tty_unlock(tty);
cancel_work_sync(&tty->port->buf.work);
+ set_bit(TTY_LDISC_HALTED, &tty->flags);
mutex_unlock(&tty->ldisc_mutex);
retry:
tty_lock(tty);