linux-kernel - Re: [PATCH 11/11] dynamic_debug: use a single printk() to emit msgs

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Date:	Fri, 15 Jul 2011 09:08:34 -0700
From:	Joe Perches <joe@...ches.com>
To:	Bart Van Assche <bvanassche@....org>
Cc:	Jason Baron <jbaron@...hat.com>, gregkh@...e.de,
	jim.cromie@...il.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 11/11] dynamic_debug: use a single printk() to emit msgs

On Fri, 2011-07-15 at 17:57 +0200, Bart Van Assche wrote:
> On Fri, Jul 15, 2011 at 5:48 PM, Joe Perches <joe@...ches.com> wrote:
> > On Fri, 2011-07-15 at 12:05 +0200, Bart Van Assche wrote:
> >> Not that's it important, but this change makes is possible to
> >> eliminate the tid[] and lineno[] arrays again. Has that been
> >> considered ?
> > tid and lineno are decimal.  Not using intermediate
> > arrays would require awkward contortions to snprintf
> > them without emitting 0 in the output.
> Sorry, but I do not agree with the above.

Hey Bart.

Then I think you don't understand the goal
of the change.

The goal is to avoid possible interleaving
of multiple printks from different threads.

> The current implementation
> of __dynamic_pr_debug() shows that an implementation without temporary
> arrays does not require any awkward constructs. See e.g.
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=lib/dynamic_debug.c
> for the source code of the current implementation of
> __dynamic_pr_debug().
> This may be subjective, but my opinion is that following that style
> results in shorter and more elegant code than the approach with the
> temporary arrays proposed in patch 11/11.

It requires awkward contortions to emit
a decimal value or "" without multiple
printks or temporaries.

cheers, Joe

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