linux-kernel - Re: [PATCH v2 4/4] printk/sound: Handle more message headers

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Date:   Fri, 11 Nov 2016 12:54:51 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Joe Perches <joe@...ches.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Jason Wessel <jason.wessel@...driver.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, Chris Mason <clm@...com>,
        Josef Bacik <jbacik@...com>, David Sterba <dsterba@...e.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/4] printk/sound: Handle more message headers

On Wed,  9 Nov 2016 13:41:31 +0100
Petr Mladek <pmladek@...e.com> wrote:

> The commit 4bcc595ccd80decb4245096e ("printk: reinstate KERN_CONT for
> printing continuation lines") allows to define more message headers
> for a single message. The motivation is that continuous lines might
> get mixed. Therefore it make sense to define the right log level
> for every piece of a cont line.
> 
> This patch allows to copy only the real message level. We should
> ignore KERN_CONT because <filename:line> is added for each message.
> By other words, we want to know where each piece of the line comes
> from.
> 
> Signed-off-by: Petr Mladek <pmladek@...e.com>
> ---
>  sound/core/misc.c | 20 ++++++++++++++------
>  1 file changed, 14 insertions(+), 6 deletions(-)
> 
> diff --git a/sound/core/misc.c b/sound/core/misc.c
> index f2e8226c88fb..45f03b1d4102 100644
> --- a/sound/core/misc.c
> +++ b/sound/core/misc.c
> @@ -71,6 +71,7 @@ void __snd_printk(unsigned int level, const char *path, int line,
>  	int kern_level;
>  	struct va_format vaf;
>  	char verbose_fmt[] = KERN_DEFAULT "ALSA %s:%d %pV";
> +	bool level_found = false;
>  #endif
>  
>  #ifdef CONFIG_SND_DEBUG
> @@ -83,15 +84,22 @@ void __snd_printk(unsigned int level, const char *path, int line,
>  	vaf.fmt = format;
>  	vaf.va = &args;
>  
> -	kern_level = printk_get_level(format);
> -	if (kern_level) {
> -		const char *end_of_header = printk_skip_level(format);
> -		memcpy(verbose_fmt, format, end_of_header - format);
> +	while ((kern_level = printk_get_level(vaf.fmt)) != 0) {
> +		const char *end_of_header = printk_skip_level(vaf.fmt);
> +
> +		/* Ignore KERN_CONT. We print filename:line for each piece. */
> +		if (kern_level >= '0' || kern_level <= '7') {

Again, the above is always true.

-- Steve

> +			memcpy(verbose_fmt, vaf.fmt, end_of_header - vaf.fmt);
> +			level_found = true;
> +		}
> +
>  		vaf.fmt = end_of_header;
> -	} else if (level)
> +	}
> +
> +	if (!level_found && level)
>  		memcpy(verbose_fmt, KERN_DEBUG, sizeof(KERN_DEBUG) - 1);
> -	printk(verbose_fmt, sanity_file_name(path), line, &vaf);
>  
> +	printk(verbose_fmt, sanity_file_name(path), line, &vaf);
>  #else
>  	vprintk(format, args);
>  #endif