Subject: Re: [PATCH] net_dbg_ratelimited: turn into no-op when !DEBUG

From: Joe Perches <[email-masked]>
Date: Tue, 04 Aug 2015 08:51:05 -0700

On Tue, 2015-08-04 at 17:07 +0200, Jason A. Donenfeld wrote:
> The pr_debug family of functions turns into a no-op when -DDEBUG is not
> specified, opting instead to call "no_printk", which gets compiled to a
> no-op (but retains gcc's nice warnings about printf-style arguments).
[]
> diff --git a/include/linux/net.h b/include/linux/net.h
[]
> @@ -239,8 +239,14 @@ do {								\
>  	net_ratelimited_function(pr_warn, fmt, ##__VA_ARGS__)
>  #define net_info_ratelimited(fmt, ...)				\
>  	net_ratelimited_function(pr_info, fmt, ##__VA_ARGS__)
> +#if defined(DEBUG)
>  #define net_dbg_ratelimited(fmt, ...)				\
>  	net_ratelimited_function(pr_debug, fmt, ##__VA_ARGS__)
> +#else
> +#define net_dbg_ratelimited(fmt, ...)				\
> +	if (0)							\
> +		no_printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
> +#endif

This should be:

#define net_dbg_ratelimited(fmt, ...)				\
do {								\
	if (0)							\
		no_printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); \
} while (0)

to be safe in if/else uses