releases/2.6.36.2/tty-ldisc-fix-open-flag-handling.patch

   1 From 7f90cfc505d613f4faf096e0d84ffe99208057d9 Mon Sep 17 00:00:00 2001
   2 From: Jiri Slaby <jslaby@suse.cz>
   3 Date: Thu, 25 Nov 2010 00:27:54 +0100
   4 Subject: TTY: ldisc, fix open flag handling
   5
   6 From: Jiri Slaby <jslaby@suse.cz>
   7
   8 commit 7f90cfc505d613f4faf096e0d84ffe99208057d9 upstream.
   9
  10 When a concrete ldisc open fails in tty_ldisc_open, we forget to clear
  11 TTY_LDISC_OPEN. This causes a false warning on the next ldisc open:
  12 WARNING: at drivers/char/tty_ldisc.c:445 tty_ldisc_open+0x26/0x38()
  13 Hardware name: System Product Name
  14 Modules linked in: ...
  15 Pid: 5251, comm: a.out Tainted: G        W  2.6.32-5-686 #1
  16 Call Trace:
  17  [<c1030321>] ? warn_slowpath_common+0x5e/0x8a
  18  [<c1030357>] ? warn_slowpath_null+0xa/0xc
  19  [<c119311c>] ? tty_ldisc_open+0x26/0x38
  20  [<c11936c5>] ? tty_set_ldisc+0x218/0x304
  21 ...
  22
  23 So clear the bit when failing...
  24
  25 Introduced in c65c9bc3efa (tty: rewrite the ldisc locking) back in
  26 2.6.31-rc1.
  27
  28 Signed-off-by: Jiri Slaby <jslaby@suse.cz>
  29 Cc: Alan Cox <alan@linux.intel.com>
  30 Reported-by: Sergey Lapin <slapin@ossfans.org>
  31 Tested-by: Sergey Lapin <slapin@ossfans.org>
  32 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
  33
  34 ---
  35  drivers/char/tty_ldisc.c |    2 ++
  36  1 file changed, 2 insertions(+)
  37
  38 --- a/drivers/char/tty_ldisc.c
  39 +++ b/drivers/char/tty_ldisc.c
  40 @@ -454,6 +454,8 @@ static int tty_ldisc_open(struct tty_str
  41                  /* BTM here locks versus a hangup event */
  42                 WARN_ON(!tty_locked());
  43                 ret = ld->ops->open(tty);
  44 +               if (ret)
  45 +                       clear_bit(TTY_LDISC_OPEN, &tty->flags);
  46                 return ret;
  47         }
  48         return 0;