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/n_tty.c b/drivers/tty/n_tty.c
index 68865d9..16793ec 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -153,6 +153,12 @@
if (left && !old_left) {
WARN_RATELIMIT(tty->port->itty == NULL,
"scheduling with invalid itty\n");
+ /* see if ldisc has been killed - if so, this means that
+ * even though the ldisc has been halted and ->buf.work
+ * cancelled, ->buf.work is about to be rescheduled
+ */
+ WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED, &tty->flags),
+ "scheduling buffer work for halted ldisc\n");
schedule_work(&tty->port->buf.work);
}
}
@@ -1624,6 +1630,8 @@
goto err_free_bufs;
tty->disc_data = ldata;
+ /* indicate buffer work may resume */
+ clear_bit(TTY_LDISC_HALTED, &tty->flags);
reset_buffer_flags(tty);
tty_unthrottle(tty);
ldata->column = 0;