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Subject: Re: [PATCH 11/11 re-post] dynamic_debug: use a single printk() to
 emit msgs
From: Joe Perches <joe@perches.com>
To: Jason Baron <jbaron@redhat.com>
Cc: Bart Van Assche <bvanassche@acm.org>, gregkh@suse.de, jim.cromie@gmail.com,
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Date: Fri, 15 Jul 2011 16:46:31 -0700
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On Fri, 2011-07-15 at 15:59 -0400, Jason Baron wrote:
> here's Bart's suggestion as re-post. It looks much cleaner to
> me...
[]
> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
[]
> @@ -422,52 +422,46 @@ static int ddebug_exec_query(char *query_string)
>  	return 0;
>  }
>  
> -static int dynamic_emit_prefix(const struct _ddebug *descriptor)
> +#define PREFIX_SIZE 64
> +#define LEFT(wrote) ((PREFIX_SIZE - wrote) > 0) ? (PREFIX_SIZE - wrote) : 0
> +
> +static char *dynamic_emit_prefix(const struct _ddebug *desc, char *buf)
>  {
> -	char tid[sizeof(int) + sizeof(int)/2 + 4];
> -	char lineno[sizeof(int) + sizeof(int)/2];
> +	int pos = 0;
>  
> -	if (descriptor->flags & _DPRINTK_FLAGS_INCL_TID) {
> +	pos += snprintf(buf + pos, LEFT(pos), "%s", KERN_DEBUG);
> +	if (desc->flags & _DPRINTK_FLAGS_INCL_TID) {
>  		if (in_interrupt())
> -			snprintf(tid, sizeof(tid), "%s", "<intr> ");
> +			pos += snprintf(buf + pos, LEFT(pos), "%s ",
> +						"<intr>");

scnprintf works without using LEFT.
snprintf does as well.

http://lkml.org/lkml/2010/7/23/375