linux-kernel - [PATCH v4 30/32] tty: Clarify multiple-references comment in TIOCSETD ioctl

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Date:	Wed, 20 Feb 2013 15:03:17 -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 30/32] tty: Clarify multiple-references comment in TIOCSETD ioctl


Signed-off-by: Peter Hurley <peter@...leysoftware.com>
---
 drivers/tty/tty_ldisc.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 84ba790..9725c94 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -567,13 +567,15 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 		tty_ldisc_restore(tty, old_ldisc);
 	}
 
-	/* At this point we hold a reference to the new ldisc and a
-	   a reference to the old ldisc. If we ended up flipping back
-	   to the existing ldisc we have two references to it */
-
 	if (tty->ldisc->ops->num != old_ldisc->ops->num && tty->ops->set_ldisc)
 		tty->ops->set_ldisc(tty);
 
+	/* At this point we hold a reference to the new ldisc and a
+	   reference to the old ldisc, or we hold two references to
+	   the old ldisc (if it was restored as part of error cleanup
+	   above). In either case, releasing a single reference from
+	   the old ldisc is correct. */
+
 	tty_ldisc_put(old_ldisc);
 
 	/*
-- 
1.8.1.2

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