linux-kernel - Re: [PATCH v2] ttyprintk: optimize tpk

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Date:   Tue, 17 Nov 2020 08:04:35 +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 v2] ttyprintk: optimize tpk_close flush code

On Tue, Nov 17, 2020 at 10:21:07AM +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>
> ---
> changes in v2:
> - rm the flush comment as tpk_flush makes it obvious.
> ---
> ---
>  drivers/char/ttyprintk.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/char/ttyprintk.c b/drivers/char/ttyprintk.c
> index 6a0059e..1f82742 100644
> --- a/drivers/char/ttyprintk.c
> +++ b/drivers/char/ttyprintk.c
> @@ -103,8 +103,7 @@ static void tpk_close(struct tty_struct *tty, struct file *filp)
>  	unsigned long flags;
>  
>  	spin_lock_irqsave(&tpkp->spinlock, flags);
> -	/* flush tpk_printk buffer */
> -	tpk_printk(NULL, 0);
> +	tpk_flush();
>  	spin_unlock_irqrestore(&tpkp->spinlock, flags);

Why did you not make the change to tpk_printk() as well that I asked you
to?

It is a static function, you control the callers, so the extra "is this
NULL, if so flush" logic makes no sense to keep around anymore, right?

thanks,

greg k-h