linux-kernel - Re: [PATCH] printk: modify console

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Message-ID: <20170717092828.GA474@jagdpanzerIV.localdomain>
Date:   Mon, 17 Jul 2017 18:28:28 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Pierre Kuo <vichy.kuo@...il.com>
Cc:     pmladek@...e.com, sergey.senozhatsky@...il.com,
        rostedt@...dmis.org, linux-kernel@...r.kernel.org, joe@...ches.com
Subject: Re: [PATCH] printk: modify console_unlock with printk-safe macros

On (07/15/17 18:36), Pierre Kuo wrote:
[..]
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index fc47863..21557cc 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -2194,8 +2194,7 @@ void console_unlock(void)
>  		size_t ext_len = 0;
>  		size_t len;
>  
> -		printk_safe_enter_irqsave(flags);
> -		raw_spin_lock(&logbuf_lock);
> +		logbuf_lock_irqsave(flags);
>  		if (seen_seq != log_next_seq) {
>  			wake_klogd = true;
>  			seen_seq = log_next_seq;
> @@ -2267,8 +2266,7 @@ void console_unlock(void)
>  	 */
>  	raw_spin_lock(&logbuf_lock);
>  	retry = console_seq != log_next_seq;
> -	raw_spin_unlock(&logbuf_lock);
> -	printk_safe_exit_irqrestore(flags);
> +	logbuf_unlock_irqrestore(flags);
>  
>  	if (retry && console_trylock())
>  		goto again;

I did it that particular way for a reason - console_unlock() does a
bunch of tricks: unlocking logbuf in the middle of printing loop,
breaking out of loop with local IRQs disabled, re-taking the logbuf
after the loop still will local IRQs disabled, etc. etc. I didn't
want to (and still don't) mix-in logbuf macros; we do things that
macros don't cover anyway. sorry, I don't agree that the patch
improves readability.

	-ss