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    Subject[PATCH 1/2] TTY: ldisc, fix open flag handling
    Date
    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>
    ---
    drivers/tty/tty_ldisc.c | 2 ++
    1 files changed, 2 insertions(+), 0 deletions(-)

    diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
    index d8e96b0..4214d58 100644
    --- a/drivers/tty/tty_ldisc.c
    +++ b/drivers/tty/tty_ldisc.c
    @@ -454,6 +454,8 @@ static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld)
    /* BTM here locks versus a hangup event */
    WARN_ON(!tty_locked());
    ret = ld->ops->open(tty);
    + if (ret)
    + clear_bit(TTY_LDISC_OPEN, &tty->flags);
    return ret;
    }
    return 0;
    --
    1.7.3.1



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