On Wed, 2013-02-20 at 17:02 +0100, Johan Hovold wrote:
> Move HUPCL handling to port shutdown so that DTR is dropped also on hang
> up (tty_port_close is a noop for hung-up ports).
>
> Also do not try to drop DTR for uninitialised ports where it has never
> been raised (e.g. after a failed open).
>
> Nine drivers currently call tty_port_close_start directly (rather than
> through tty_port_close) and seven of them lower DTR as part of their
> close (if the port has been initialised). Fixup the remaining two
> drivers so that it continues to be lowered also on normal (non-HUP)
> close. [ Note that most of those other seven drivers did not expect DTR
> to have been dropped by tty_port_close_start in the first place. ]
>
> Signed-off-by: Johan Hovold <jhovold@xxxxxxxxx>
> ---
> drivers/tty/mxser.c | 4 ++++
> drivers/tty/n_gsm.c | 4 ++++
> drivers/tty/tty_port.c | 23 +++++++++++++----------
> 3 files changed, 21 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/tty/mxser.c b/drivers/tty/mxser.c
> index 484b6a3..c547887 100644
> --- a/drivers/tty/mxser.c
> +++ b/drivers/tty/mxser.c
> @@ -1084,6 +1084,10 @@ static void mxser_close(struct tty_struct *tty, struct file *filp)
> mutex_lock(&port->mutex);
> mxser_close_port(port);
> mxser_flush_buffer(tty);
> + if (test_bit(ASYNCB_INITIALIZED, &port->flags)) {
> + if (tty->termios.c_cflag & HUPCL)
> + tty_port_lower_dtr_rts(port);
> + }
> mxser_shutdown_port(port);
> clear_bit(ASYNCB_INITIALIZED, &port->flags);
> mutex_unlock(&port->mutex);
> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
> index 4a43ef5d7..049013e 100644
> --- a/drivers/tty/n_gsm.c
> +++ b/drivers/tty/n_gsm.c
> @@ -2968,6 +2968,10 @@ static void gsmtty_close(struct tty_struct *tty, struct file *filp)
> if (tty_port_close_start(&dlci->port, tty, filp) == 0)
> goto out;
> gsm_dlci_begin_close(dlci);
> + if (test_bit(ASYNCB_INITIALIZED, &dlci->port.flags)) {
> + if (tty->termios.c_cflag & HUPCL)
> + tty_port_lower_dtr_rts(&dlci->port);
> + }
> tty_port_close_end(&dlci->port, tty);
> tty_port_tty_set(&dlci->port, NULL);
> out:
> diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
> index 57a061e..506f579 100644
> --- a/drivers/tty/tty_port.c
> +++ b/drivers/tty/tty_port.c
> @@ -198,15 +198,25 @@ EXPORT_SYMBOL(tty_port_tty_set);
>
> static void tty_port_shutdown(struct tty_port *port)
> {
> + struct tty_struct *tty = tty_port_tty_get(port);
> +
I know I said this was done, but if this hasn't been pushed into
tty-next yet, I'd rather this was:
static void tty_port_shutdown(struct tty_port *port,
struct tty_struct *tty)
and not get the port reference. Both call sites already ensure that
there is a kref on the tty or tty is NULL.
(I ended up re-looking at this patch to double-check that it won't drop
DTR for the console, which it doesn't so that is good).
> mutex_lock(&port->mutex);
> if (port->console)
> goto out;
>
> if (test_and_clear_bit(ASYNCB_INITIALIZED, &port->flags)) {
> + /*
> + * Drop DTR/RTS if HUPCL is set. This causes any attached
> + * modem to hang up the line.
> + */
> + if (!tty || tty->termios.c_cflag & HUPCL)
> + tty_port_lower_dtr_rts(port);
> +
> if (port->ops->shutdown)
> port->ops->shutdown(port);
> }
> out:
> + tty_kref_put(tty);
> mutex_unlock(&port->mutex);
> }
>
> @@ -225,15 +235,13 @@ void tty_port_hangup(struct tty_port *port)
> spin_lock_irqsave(&port->lock, flags);
> port->count = 0;
> port->flags &= ~ASYNC_NORMAL_ACTIVE;
> - if (port->tty) {
> + if (port->tty)
> set_bit(TTY_IO_ERROR, &port->tty->flags);
> - tty_kref_put(port->tty);
> - }
> - port->tty = NULL;
> spin_unlock_irqrestore(&port->lock, flags);
> + tty_port_shutdown(port);
> + tty_port_tty_set(port, NULL);
> wake_up_interruptible(&port->open_wait);
> wake_up_interruptible(&port->delta_msr_wait);
> - tty_port_shutdown(port);
> }
> EXPORT_SYMBOL(tty_port_hangup);
>
> @@ -452,11 +460,6 @@ int tty_port_close_start(struct tty_port *port,
> /* Flush the ldisc buffering */
> tty_ldisc_flush(tty);
>
> - /* Drop DTR/RTS if HUPCL is set. This causes any attached modem to
> - hang up the line */
> - if (tty->termios.c_cflag & HUPCL)
> - tty_port_lower_dtr_rts(port);
> -
> /* Don't call port->drop for the last reference. Callers will want
> to drop the last active reference in ->shutdown() or the tty
> shutdown path */
--
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