linux-kernel - Re: [PATCH printk 3/5] printk: use buffer pool for sprint buffers

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Message-ID: <20200924012132.GA577@jagdpanzerIV.localdomain>
Date:   Thu, 24 Sep 2020 10:21:32 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:     John Ogness <john.ogness@...utronix.de>
Cc:     Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH printk 3/5] printk: use buffer pool for sprint buffers

On (20/09/22 17:44), John Ogness wrote:
[..]
>  int vprintk_store(int facility, int level,
>  		  const struct dev_printk_info *dev_info,
>  		  const char *fmt, va_list args)
>  {
> -	static char textbuf[LOG_LINE_MAX];
> -	char *text = textbuf;
>  	size_t text_len;
>  	enum log_flags lflags = 0;
> +	unsigned long irqflags;
> +	int sprint_id;
> +	char *text;
> +	int ret;
> +
> +	text = get_sprint_buf(&sprint_id, &irqflags);
> +	if (WARN_ON_ONCE(!text))
> +		return 0;

So we failed to get the buffer. How likely that this recursive
WARN_ON_ONCE()->printk()->get_sprint_buf() will be able to get one?
I would rather expect that we will entirely lose WARN_ON_ONCE().

	-ss