linux-kernel - [PATCH v4 32/32] tty: Drop "tty is NULL" flip buffer diagnostic

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Date:	Wed, 20 Feb 2013 15:03:19 -0500
From:	Peter Hurley <peter@...leysoftware.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.cz>
Cc:	Sasha Levin <levinsasha928@...il.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
	Ilya Zykov <ilya@...x.ru>, Dave Jones <davej@...hat.com>,
	Michael Ellerman <michael@...erman.id.au>,
	Shawn Guo <shawn.guo@...aro.org>,
	Peter Hurley <peter@...leysoftware.com>
Subject: [PATCH v4 32/32] tty: Drop "tty is NULL" flip buffer diagnostic

Although this warning uncovered a multitude of races and errors
in the tty and ldisc layers, this diagnostic now has too many
false-positives.

An expected outcome of the separation of driver i/o paths from
tty lifetimes (added in 3.9) is that the tty may already be
in advanced stages of teardown when scheduled flip buffer work
runs. Ldisc i/o is prevented in this case because flush_to_ldisc()
cannot acquire an ldisc reference.

Signed-off-by: Peter Hurley <peter@...leysoftware.com>
---
 drivers/tty/tty_buffer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 0dd35ce..8e8d730 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -425,7 +425,7 @@ static void flush_to_ldisc(struct work_struct *work)
 	struct tty_ldisc *disc;
 
 	tty = port->itty;
-	if (WARN_RATELIMIT(tty == NULL, "tty is NULL\n"))
+	if (tty == NULL)
 		return;
 
 	disc = tty_ldisc_ref(tty);
-- 
1.8.1.2

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