From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ivo Sieben Subject: [PATCH] [tty]: Report warning when low_latency flag is wrongly used Date: Wed, 24 Oct 2012 14:35:42 +0200 Message-ID: <1351082142-28633-1-git-send-email-meltedpianoman@gmail.com> References: <20121023111659.6f4427c7@bob.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain Cc: Ivo Sieben To: Greg KH , , RT Return-path: Received: from ch1ehsobe005.messaging.microsoft.com ([216.32.181.185]:51178 "EHLO ch1outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758524Ab2JXMf6 (ORCPT ); Wed, 24 Oct 2012 08:35:58 -0400 In-Reply-To: <20121023111659.6f4427c7@bob.linux.org.uk> Sender: linux-rt-users-owner@vger.kernel.org List-ID: 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 --- 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 06725f5..6cf87d7 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) -- 1.7.9.5