netdev - Re: [PATCH] SUNRPC: Mark buffer used for debug printks with __maybe

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Date:	Wed, 20 Feb 2008 09:23:24 -0800
From:	Joe Perches <joe@...ches.com>
To:	Trond Myklebust <trond.myklebust@....uio.no>
Cc:	Patrick McHardy <kaber@...sh.net>,
	Pavel Emelyanov <xemul@...nvz.org>,
	"J. Bruce Fields" <bfields@...i.umich.edu>,
	Linux Netdev List <netdev@...r.kernel.org>
Subject: Re: [PATCH] SUNRPC: Mark buffer used for debug printks
	with	__maybe_unused

On Wed, 2008-02-20 at 12:02 -0500, Trond Myklebust wrote:
> > #ifdef DEBUG
> > #define some_print_wrapper(fmt, arg...) \
> >         do { if (0) printk(KERN_DEBUG fmt, ##arg); } while (0)
> > #else
> > #define some_print_wrapper(fmt, arg...) \
> > 	printk(KERN_DEBUG fmt, ##arg)
> > #endif
> Have you actually read include/linux/sunrpc/debug.h?

Yes, I have.

What's there:

#define dfprintk(fac, args...) do ; while (0)

vs what's suggested:

#define dfprintk(fac, args...) \
	do  { if (0) printk(##args); } while (0);

No argument verification is done to args

There has been code that fails to compile with -DDEBUG when
the code use two different #ifdef DEBUG #else macros.
I think some of the USB code was reworked because of that.

The extra verification is just a guard against bad arguments
when compiled normally.  It's similar to what's done in kernel.h
pr_debug without the __attribute__((format(printf,x,y))) so
that calls made as arguments to functions aren't called
unnecessarily.

cheers, Joe

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