Subject: Re: linux-next: driver-core tree build failure

From: Martin Schwidefsky <[email-masked]>
Date: Tue, 10 Mar 2009 14:53:11 +0100

On Tue, 10 Mar 2009 14:31:17 +0100 (CET)
Geert Uytterhoeven <[email-masked]> wrote:

> crypto/zlib.c has:
> 
>     #define pr_fmt(fmt)     "%s: " fmt, __func__
> 
> If CONFIG_DYNAMIC_DEBUG is set, include/linux/kernel.h has:
> 
> #define pr_debug(fmt, ...) do { \
> 	dynamic_pr_debug(pr_fmt(fmt), ##__VA_ARGS__); \
> 	} while (0)
> 
> include/linux/dynamic_debug.h has:
> 
> #define dynamic_pr_debug(fmt, ...) do {					\
> 	static struct _ddebug descriptor				\
> 	__used								\
> 	__attribute__((section("__verbose"), aligned(8))) =		\
> 	{ KBUILD_MODNAME, __func__, __FILE__, fmt, DEBUG_HASH,	\
> 		DEBUG_HASH2, __LINE__, _DPRINTK_FLAGS_DEFAULT };	\
> 	if (__dynamic_dbg_enabled(descriptor))				\
> 		printk(KERN_DEBUG KBUILD_MODNAME ":" fmt,		\
> 				##__VA_ARGS__);				\
> 	} while (0)

The dynamic_pr_debug macro currently works only with pr_fmt definitions
that do not add additional parameters. The way how we use the pr_fmt
macro is:

#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

The same could be done with the problematic pr_fmt definition:

#define pr_fmt(fmt)     __func__ ": " fmt

> BTW, Martin: Is `#define pr_fmt(fmt)     "%s: " fmt, __func__' a valid and
> intended usage of your pr_fmt() infrastructure?

The indended use is a simple prefix to the format string. To paste an
additional parameter is an interesting use of the pr_fmt macro ..

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.