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

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: Windows password security audit tool. GUI, reports in PDF.

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

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