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

[Peter Hurley <peter@hurleysoftware.com>]

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);
> 
>