[34-longterm 055/209] TTY: ldisc, fix open flag handling

From: Paul Gortmaker
Date: Thu Apr 14 2011 - 14:25:39 EST

From: Jiri Slaby <jslaby@xxxxxxx>

| This is a commit scheduled for the next v2.6.34 longterm release. |
| If you see a problem with using this for longterm, please comment.|

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

Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
Cc: Alan Cox <alan@xxxxxxxxxxxxxxx>
Reported-by: Sergey Lapin <slapin@xxxxxxxxxxx>
Tested-by: Sergey Lapin <slapin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
drivers/char/tty_ldisc.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c
index 7af1a15..236628f 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 */
ret = ld->ops->open(tty);
+ if (ret)
+ clear_bit(TTY_LDISC_OPEN, &tty->flags);
return ret;

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