Re: [Bug 8473] New: Oops: 0010 [1] SMP

[Paul Fulghum <paulkf@microgate.com>]

On Thu, 2007-06-07 at 20:16 -0700, Andrew Morton wrote:
> On Fri, 8 Jun 2007 05:06:29 +0200 Björn Steinbrink <B.Steinbrink@gmx.de> wrote:
> > This is do_tty_hangup() exchanging the fops while we're waiting for the
> > lock. The new fops (hung_up_tty_fops) only have the unlocked variant and
> > thus we Oops our way.
> 
> ah, yes, that explains it, thanks.  Culprit:
> 
> commit e10cc1df1d2014f68a4bdcf73f6dd122c4561f94
> Author: Paul Fulghum <paulkf@microgate.com>
> Date:   Thu May 10 22:22:50 2007 -0700
> 
>     tty: add compat_ioctl
>     
>     Add compat_ioctl method for tty code to allow processing of 32 bit ioctl
>     calls on 64 bit systems by tty core, tty drivers, and line disciplines.

OK, the change of hung_up_tty_ioctl() from locked to unlocked
is not necessary for this patch. On the surface it seemed a clever
way of not needing two different functions to do the same simple:

return cmd == TIOCSPGRP ? -ENOTTY : -EIO;

which does not need any locking for its own sake. But clearly
the hangup behavior requires the locked version.

I'll redo the patch with hung_up_tty_ioctl remaining locked.

That will separate the compat ioctl stuff from this issue.

-- 
Paul Fulghum
Microgate Systems, Ltd