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SubjectRe: [Fwd: [PATCH v2 0/4] TTY: port hangup and close fixes]
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On Thu, 2013-03-07 at 10:43 +0100, Johan Hovold wrote:
> On Wed, Mar 06, 2013 at 02:14:56PM -0500, Peter Hurley wrote:
> > On Wed, 2013-03-06 at 17:52 +0100, Johan Hovold wrote:
> > > Yes, I did. First, the order should not matter for blocked opens as they
> > > will exit their wait loops based on tty_hung_up_p(filp) either way.
> >
> > Only if the open() was ever successful, otherwise the filp won't be in
> > the tty->tty_files list. That's why the blocking opens also check
> > ASYNC_INITIALIZED (or ASYNCB_INITIALIZED depending on which they use).
> > Which is why I said it was actually better to shutdown() first, then
> > wake up the blocked opens.
>
> ASYNC_INITIALIZED have also been cleared when the blocked opens are
> being woken up from tty_port_close_end.
>
> And the filp is added to tty_files before open() is called:
>
> ===> tty_add_file(tty, filp);
>
> check_tty_count(tty, __func__);
> if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
> tty->driver->subtype == PTY_TYPE_MASTER)
> noctty = 1;
> #ifdef TTY_DEBUG_HANGUP
> printk(KERN_DEBUG "%s: opening %s...\n", __func__, tty->name);
> #endif
> if (tty->ops->open)
> ===> retval = tty->ops->open(tty, filp);
>
> so a blocked open must have hung_up_tty_fops when woken up from hangup,
> right?

You're right, my mistake.

> Either way, postponing wake-up somewhat in tty_port_hangup should be
> fine.

Yep.

Regards,
Peter Hurley



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