Re: [PATCH 1/1] TTY: serial_core, fix dtr_rts NULL dereference

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

> > The uart helper layer assumes here (and a couple of other spots) that the
> > IRQ handler for the tty takes the port lock.
> 
> The oopsing path is through open BTW:
> -> uart_open
>  -> tty_port_block_til_ready
>   -> tty_port_raise_dtr_rts
>    -> uart_dtr_rts
> 
> > I think the *right* fix is probably to pass port not port->tty into the
> > helper in the first place but that seems to ripple into a lot of drivers.
> > 
> > (passing port->tty to things that then go tty->port is braindead and
> > causes half the mess in the tty/serial code)
> 
> I seem to miss the point. uart_update_termios needs tty, not port.


Actually I think it needs shooting having looked more closely

It does 3 things

1. It copies a flag across as part of a console hack. That should be done
elsewhere - eg in uart_startup

2. It sets the speed, which was already done by uart_startup

3. It goes poking around in the CBAUD flag before playing with DTR and
RTS which will have no effect as we *already* set the flags in
uart_dtr_rts

Am I missing something ?