From 89f26850f00bc19c52e62e47802e7088cb87f946 Mon Sep 17 00:00:00 2001
From: Jiri Slaby <jslaby@suse.cz>
Date: Thu, 25 Nov 2010 00:27:54 +0100
Subject: [PATCH] TTY: ldisc, fix open flag handling

commit 7f90cfc505d613f4faf096e0d84ffe99208057d9 upstream.

When a concrete ldisc open fails in tty_ldisc_open, we forget to clear
TTY_LDISC_OPEN. This causes a false warning on the next ldisc open:
WARNING: at drivers/char/tty_ldisc.c:445 tty_ldisc_open+0x26/0x38()
Hardware name: System Product Name
Modules linked in: ...
Pid: 5251, comm: a.out Tainted: G        W  2.6.32-5-686 #1
Call Trace:
 [<c1030321>] ? warn_slowpath_common+0x5e/0x8a
 [<c1030357>] ? warn_slowpath_null+0xa/0xc
 [<c119311c>] ? tty_ldisc_open+0x26/0x38
 [<c11936c5>] ? tty_set_ldisc+0x218/0x304
...

So clear the bit when failing...

Introduced in c65c9bc3efa (tty: rewrite the ldisc locking) back in
2.6.31-rc1.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@linux.intel.com>
Reported-by: Sergey Lapin <slapin@ossfans.org>
Tested-by: Sergey Lapin <slapin@ossfans.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 drivers/char/tty_ldisc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c
index 7af1a1563e8f..236628f3fea1 100644
--- a/drivers/char/tty_ldisc.c
+++ b/drivers/char/tty_ldisc.c
@@ -452,6 +452,8 @@ static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld)
                 /* BKL here locks verus a hangup event */
 		lock_kernel();
 		ret = ld->ops->open(tty);
+		if (ret)
+			clear_bit(TTY_LDISC_OPEN, &tty->flags);
 		unlock_kernel();
 		return ret;
 	}
-- 
2.39.5