linux-kernel - Re: [PATCH] ttyprintk: optimize tpk

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Date:   Thu, 12 Nov 2020 08:52:23 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Junyong Sun <sunjy516@...il.com>
Cc:     arnd@...db.de, sunjunyong@...omi.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ttyprintk: optimize tpk_close flush code

On Wed, Nov 04, 2020 at 02:02:24PM +0800, Junyong Sun wrote:
> tpk_printk(NULL,0) do nothing but call tpk_flush to
> flush buffer, so why don't use tpk_flush diretcly?
> this is a small optimization.
> 
> Signed-off-by: Junyong Sun <sunjunyong@...omi.com>
> ---
>  drivers/char/ttyprintk.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/char/ttyprintk.c b/drivers/char/ttyprintk.c
> index 6a0059e..2ce78b3 100644
> --- a/drivers/char/ttyprintk.c
> +++ b/drivers/char/ttyprintk.c
> @@ -104,7 +104,7 @@ static void tpk_close(struct tty_struct *tty, struct file *filp)
>  
>  	spin_lock_irqsave(&tpkp->spinlock, flags);
>  	/* flush tpk_printk buffer */
> -	tpk_printk(NULL, 0);
> +	tpk_flush();

If you do this, then please remove the logic in tpk_flush() that handles
NULL as now that logic will not be needed at all, right?

Also the comment here wouldn't be needed as the code obviously does that
based on the function call being made :)

thanks,

greg k-h