From b8b345bae8cb6745f2afdd28bb2d93f9cf0d7f2c Mon Sep 17 00:00:00 2001
From: Ivo Sieben <meltedpianoman@gmail.com>
Date: Wed, 24 Oct 2012 14:35:42 +0200
Subject: [PATCH] TTY: Report warning when low_latency flag is wrongly used
When a driver has the low_latency flag set and uses the schedule_flip()
function to initiate copying data to the line discipline, a workqueue is
scheduled in but never actually flushed. This is incorrect use of the
low_latency flag (driver should not support the low_latency flag, or use
the tty_flip_buffer_push() function instead). Make sure a warning is
reported to catch incorrect use of the low_latency flag.
This patch goes with: cee4ad1ed90a0959fc29f9d30a2526e5e9522cfa
Signed-off-by: Ivo Sieben <meltedpianoman@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/tty/tty_buffer.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 06725f5cc819..6cf87d7afb7e 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -365,6 +365,7 @@ void tty_schedule_flip(struct tty_struct *tty)
{
struct tty_bufhead *buf = &tty->port->buf;
unsigned long flags;
+ WARN_ON(tty->low_latency);
spin_lock_irqsave(&buf->lock, flags);
if (buf->tail != NULL)
--
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