From: Steven Rostedt <rostedt@goodmis.org>
To: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] tracing: don't macro-expand arguments before stringification in TP_printk
Date: Mon, 22 Feb 2016 22:23:08 -0500 [thread overview]
Message-ID: <20160222222308.12bdfeb3@grimm.local.home> (raw)
In-Reply-To: <87io3z6xur.fsf@rasmusvillemoes.dk>
On Wed, 16 Dec 2015 01:28:12 +0100
Rasmus Villemoes <linux@rasmusvillemoes.dk> wrote:
> Bah, just found 0462b5664b (ftrace: Output REC->var instead of
> __entry->var for trace format). There's some magic here I don't
> understand, but I'm wondering if '__entry' wouldn't do just as well as
> 'REC' for the tools that try to parse these strings.
>
>
Sorry for the late reply, but I just found this in my INBOX :-)
Several tools already exist that use REC to parse. It would be ABI
breakage to suddenly convert it to __entry.
Not to mention, even in your example of:
((unsigned int) ((REC->dev) >> 20)), ((unsigned int) ((REC->dev) & ((1U << 20) - 1)))
which came from
MAJOR(__entry->dev), MINOR(__entry->dev),
The parsing tools don't know how to parse MAJOR or MINOR but they do
know how to do the above macro expansions.
Just an FYI,
-- Steve
prev parent reply other threads:[~2016-02-23 3:23 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-15 23:59 [PATCH] tracing: don't macro-expand arguments before stringification in TP_printk Rasmus Villemoes
2015-12-16 0:28 ` Rasmus Villemoes
2016-02-23 3:23 ` Steven Rostedt [this message]
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