Commit b8b345ba authored Oct 24, 2012 by Ivo Sieben Committed by Greg Kroah-Hartman Oct 24, 2012

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: cee4ad1e

Signed-off-by: Ivo Sieben <meltedpianoman@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 6b898c07

drivers/tty/tty_buffer.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -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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