From mboxrd@z Thu Jan  1 00:00:00 1970
From: Joe Perches <joe@perches.com>
Subject: Re: [PATCH 4/4] jbd: use a single printk for jbd_debug()
Date: Thu, 01 Aug 2013 12:21:05 -0700
Message-ID: <1375384865.2034.70.camel@joe-AO722>
References: <1375383668-8072-1-git-send-email-paul.gortmaker@windriver.com>
	 <1375383668-8072-5-git-send-email-paul.gortmaker@windriver.com>
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Cc: Jan Kara <jack@suse.cz>, Andrew Morton <akpm@linux-foundation.org>,
	linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org
To: Paul Gortmaker <paul.gortmaker@windriver.com>
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On Thu, 2013-08-01 at 15:01 -0400, Paul Gortmaker wrote:
> Backport of jbd2 commit 169f1a2a87aae44034da4b9f81be1683d33de6d0
> ("jbd2: use a single printk for jbd_debug()")

Hey Paul.

> diff --git a/include/linux/jbd.h b/include/linux/jbd.h
[]
> @@ -56,16 +56,13 @@
>  #define JBD_EXPENSIVE_CHECKING
>  extern ushort journal_enable_debug;
>  
> -#define jbd_debug(n, f, a...)						\
> -	do {								\
> -		if ((n) <= journal_enable_debug) {			\
> -			printk (KERN_DEBUG "(%s, %d): %s: ",		\
> -				__FILE__, __LINE__, __func__);	\
> -			printk (f, ## a);				\
> -		}							\
> -	} while (0)
> +void __jbd_debug(int level, const char *file, const char *func,
> +		 unsigned int line, const char *fmt, ...
> +
> +#define jbd_debug(n, fmt, a...) \
> +	__jbd_debug((n), __FILE__, __func__, __LINE__, (fmt), ##a)
>  #else
> -#define jbd_debug(f, a...)	/**/
> +#define jbd_debug(n, fmt, a...)    /**/
>  #endif

It might have been (and may still be) simpler/better
to use a single macro like:

#define jbd_dbg(n, fmt, ...)			\
do {						\
	if ((n) < journal_enable_debug)		\
		pr_debug(fmt, ##__VA_ARGS__);	\
} while (0)

and then use dynamic_debug to add the __func__,
and __LINE__ when desired.

echo -n 'module jbd +pfl' <dynamic_debug>/control