Re: [PATCHv5 05/17] tty: don't allow ldisc dcd_change() after ldisc halt

Alexander Gordeev
2010-11-25T13:31:32Z

[-- Attachment #1: Type: text/plain, Size: 887 bytes --]

В Wed, 24 Nov 2010 22:36:00 +0000
Alan Cox <alan@linux.intel.com> пишет:

> > Yes, indeed, it's a bug. Please consider the following example:
> >
> > CPU1 CPU2
> > =========================================================
> > uart_handle_dcd_change() { tty_set_ldisc() {
> > ld = tty_ldisc_ref(...) ...
>
> [We have a reference]
> > ... tty_ldisc_halt(...)
> [Should block]
>
> > I think tty code is exactly the right place to fix this bug; this is
> > what my patch is for.
>
> More special case magic on top of the current crap isn't the right fix
> here, tty_ldisc_halt needs to wait for the references to hit zero.

Didn't know that current design is crap. :)
Ok, I think I'll add a new waitqueue and a new bit (TTY_LDISC_NOREF)
that halt will wait for. Is it good?

--
Alexander

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 490 bytes --]