Re: [PATCH 1/3] TTY: use class_find_device to find port in uart_suspend/resume.

Peter Hurley
2015-03-25T16:20:36Z

Hi Neil,

On 03/18/2015 01:58 AM, NeilBrown wrote:
> uart_{suspend,resume}_port seach the children of a uart device
> to find a particular tty device.
> This requires all the ttys to be direct children of the uart.
>
> A future patch will allow a 'tty_slave' to intervene between
> the port and the uart, voiding this requirement.
>
> So change to use class_find_device. This is made possibly by
> exporting a "tty_find_device" from tty_io.c

Comments below.

> Signed-off-by: NeilBrown <neil@brown.name>
> ---
> drivers/tty/serial/serial_core.c | 21 ++++++++-------------
> drivers/tty/tty_io.c | 6 ++++++
> include/linux/tty.h | 1 +
> 3 files changed, 15 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> index 6a1055ae3437..7abb7474870a 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -1960,26 +1960,19 @@ struct uart_match {
> struct uart_driver *driver;
> };
>
> -static int serial_match_port(struct device *dev, void *data)
> -{
> - struct uart_match *match = data;
> - struct tty_driver *tty_drv = match->driver->tty_driver;
> - dev_t devt = MKDEV(tty_drv->major, tty_drv->minor_start) +
> - match->port->line;
> -
> - return dev->devt == devt; /* Actually, only one tty per port */
> -}
>
> int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
> {
> struct uart_state *state = drv->state + uport->line;
> struct tty_port *port = &state->port;
> struct device *tty_dev;
> - struct uart_match match = {uport, drv};
> + dev_t devt = MKDEV(drv->tty_driver->major,
> + drv->tty_driver->minor_start) +
> + uport->line;
>
> mutex_lock(&port->mutex);
>
> - tty_dev = device_find_child(uport->dev, &match, serial_match_port);
> + tty_dev = tty_find_device(devt);
> if (device_may_wakeup(tty_dev)) {
> if (!enable_irq_wake(uport->irq))
> uport->irq_wake = 1;
> @@ -2039,12 +2032,14 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
> struct uart_state *state = drv->state + uport->line;
> struct tty_port *port = &state->port;
> struct device *tty_dev;
> - struct uart_match match = {uport, drv};
> struct ktermios termios;
> + dev_t devt = MKDEV(drv->tty_driver->major,
> + drv->tty_driver->minor_start) +
> + uport->line;
>
> mutex_lock(&port->mutex);
>
> - tty_dev = device_find_child(uport->dev, &match, serial_match_port);
> + tty_dev = tty_find_device(devt);
> if (!uport->suspended && device_may_wakeup(tty_dev)) {
> if (uport->irq_wake) {
> disable_irq_wake(uport->irq);
> diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
> index 51f066aa375e..27632ad17d6f 100644
> --- a/drivers/tty/tty_io.c
> +++ b/drivers/tty/tty_io.c
> @@ -3077,6 +3077,12 @@ static struct device *tty_get_device(struct tty_struct *tty)
> return class_find_device(tty_class, NULL, &devt, dev_match_devt);
> }
>
> +struct device *tty_find_device(dev_t devt)
> +{
> + return class_find_device(tty_class, NULL, &devt, dev_match_devt);
> +}
> +EXPORT_SYMBOL(tty_find_device);
> +

Would you please replace tty_get_device() usage with tty_find_device()
(and keep the function comment from tty_get_device())?

Regards,
Peter Hurley

>
> /**
> * alloc_tty_struct
> diff --git a/include/linux/tty.h b/include/linux/tty.h
> index 358a337af598..04d5f1213700 100644
> --- a/include/linux/tty.h
> +++ b/include/linux/tty.h
> @@ -461,6 +461,7 @@ extern void tty_vhangup(struct tty_struct *tty);
> extern int tty_hung_up_p(struct file *filp);
> extern void do_SAK(struct tty_struct *tty);
> extern void __do_SAK(struct tty_struct *tty);
> +extern struct device *tty_find_device(dev_t devt);
> extern void no_tty(void);
> extern void tty_flush_to_ldisc(struct tty_struct *tty);
> extern void tty_buffer_free_all(struct tty_port *port);
>
>