linux-kernel - Re: [PATCH v2 6/7] serial: liteuart: separate RX loop from poll timer

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1c902ee8-d33d-c2d0-7eef-719f59f3a64@linux.intel.com>
Date:   Thu, 10 Nov 2022 13:01:47 +0200 (EET)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Gabriel Somlo <gsomlo@...il.com>
cc:     LKML <linux-kernel@...r.kernel.org>,
        linux-serial <linux-serial@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>, kgugala@...micro.com,
        mholenko@...micro.com, joel@....id.au,
        david.abdurachmanov@...il.com, florent@...oy-digital.fr,
        geert@...ux-m68k.org
Subject: Re: [PATCH v2 6/7] serial: liteuart: separate RX loop from poll
 timer

On Wed, 9 Nov 2022, Gabriel Somlo wrote:

> Move the character-receive (RX) loop to its own dedicated function,
> and (for now) call that from the poll timer, liteuart_timer().
> 
> This is in preparation for adding IRQ support to the receive path.
> 
> Signed-off-by: Gabriel Somlo <gsomlo@...il.com>
> ---
>  drivers/tty/serial/liteuart.c | 25 +++++++++++++++----------
>  1 file changed, 15 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/tty/serial/liteuart.c b/drivers/tty/serial/liteuart.c
> index 047d5ad32e13..aa7052280197 100644
> --- a/drivers/tty/serial/liteuart.c
> +++ b/drivers/tty/serial/liteuart.c
> @@ -67,29 +67,34 @@ static struct uart_driver liteuart_driver = {
>  #endif
>  };
>  
> -static void liteuart_timer(struct timer_list *t)
> +static void liteuart_rx_chars(struct uart_port *port)
>  {
> -	struct liteuart_port *uart = from_timer(uart, t, timer);
> -	struct uart_port *port = &uart->port;
>  	unsigned char __iomem *membase = port->membase;
> -	unsigned int flg = TTY_NORMAL;
> -	int ch;
> -	unsigned long status;
> +	unsigned int status;
> +	unsigned char ch;
>  
>  	while ((status = !litex_read8(membase + OFF_RXEMPTY)) == 1) {
>  		ch = litex_read8(membase + OFF_RXTX);
>  		port->icount.rx++;
>  
>  		/* necessary for RXEMPTY to refresh its value */
> -		litex_write8(membase + OFF_EV_PENDING, EV_TX | EV_RX);
> +		litex_write8(membase + OFF_EV_PENDING, EV_RX);
>  
>  		/* no overflow bits in status */
>  		if (!(uart_handle_sysrq_char(port, ch)))
> -			uart_insert_char(port, status, 0, ch, flg);
> -
> -		tty_flip_buffer_push(&port->state->port);
> +			uart_insert_char(port, status, 0, ch, TTY_NORMAL);
>  	}
>  
> +	tty_flip_buffer_push(&port->state->port);

This change is doing extra stuff besides moving rx to a dedicated 
function.

I see no reason why those other changes couldn't be put into an entirely 
separate patch. Also, please described those changes properly in the 
commit message (answer the why? question).

-- 
 i.

> +}
> +
> +static void liteuart_timer(struct timer_list *t)
> +{
> +	struct liteuart_port *uart = from_timer(uart, t, timer);
> +	struct uart_port *port = &uart->port;
> +
> +	liteuart_rx_chars(port);
> +
>  	mod_timer(&uart->timer, jiffies + uart_poll_timeout(port));
>  }
>  
>