linux-kernel - Re: RFC: Use dynamic-debug with pr

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Date:	Wed, 10 Aug 2011 23:06:54 -0700
From:	Joe Perches <joe@...ches.com>
To:	Jim Cromie <jim.cromie@...il.com>
Cc:	Jason Baron <jbaron@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>, linux-i2c@...r.kernel.org
Subject: Re: RFC: Use dynamic-debug with pr_debug when -DDEBUG is set

On Wed, 2011-08-10 at 23:44 -0600, Jim Cromie wrote:
> On Wed, Aug 10, 2011 at 7:03 PM, Joe Perches <joe@...ches.com> wrote:
> > On Wed, 2011-08-10 at 20:20 -0400, Jason Baron wrote:
> >> On Wed, Aug 10, 2011 at 05:01:37PM -0700, Joe Perches wrote:
> >> > Perhaps another way to enable pr_debug use
> >> > is to reverse the order of dynamic_pr_debug
> >> > defines.
> >> > ie:  change printk.h:
> >> > #if defined(CONFIG_DYNAMIC_DEBUG)
> >> > /* dynamic_pr_debug() uses pr_fmt() internally so we don't need it here */
> >> > #define pr_debug(fmt, ...) \
> >> >     dynamic_pr_debug(fmt, ##__VA_ARGS__)
> >> > #elif defined(DEBUG)
> >> > #define pr_debug(fmt, ...) \
> >> >     printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
> >> > and change dynamic_debug.h:
> >> > #define DPRINTK_FLAGS_DEFAULT 0
> >> > to:
> >> > #if defined DEBUG
> >> > #define DPRINTK_FLAGS_DEFAULT DPRINTK_FLAGS_PRINT
> >> > #else
> >> > #define DPRINT_FLAGS_DEFAULT 0
> >> > #endif
> >> > That seems pretty sensible to me.  Jason?
> >> cool idea. I like it.
> > You've got a bunch of patches ready to
> > be pulled/queued, so I think you should
> > do it.
[]
> Ive just added this.  It works nicely, with one trivial change
> to add MODNAME, imitating the common non-dynamic-debug usage:
> #if defined DEBUG
> #define _DPRINTK_FLAGS_DEFAULT _DPRINTK_FLAGS_PRINT |
> _DPRINTK_FLAGS_INCL_MODNAME

Right now, I think you should _not_ 
add DPRINTK_FLAGS_INCL_MODNAME to the
DEBUG DPRINTK_FLAGS_DEFAULT nor should
INCL_MODNAME  be added to any default output
style.

Look for things like:
	pr_debug(PFX "foo...");
and
	pr_debug("some_prefix: foo...");

For instance:

$ grep -rP --include=*.[ch] "pr_debug\s*\(\s*\"\w+:" *

There are just too many uses of pr_debug where
defaulting KBUILD_MODNAME on will just cause some
unnecessary duplication of output.

Maybe do this in a year or two when more of
the current printks are sifted.


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