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Message-ID: <20090503183650.GB6010@nowhere>
Date: Sun, 3 May 2009 20:36:51 +0200
From: Frederic Weisbecker <fweisbec@...il.com>
To: Christoph Hellwig <hch@...radead.org>
Cc: Josh Stone <jistone@...hat.com>, Jason Baron <jbaron@...hat.com>,
mingo@...e.hu, rostedt@...dmis.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] export softirq_to_name symbol
On Fri, May 01, 2009 at 04:10:28PM -0400, Christoph Hellwig wrote:
> On Fri, May 01, 2009 at 01:07:34PM -0700, Josh Stone wrote:
> > I'm adding SystemTap support for the format strings in the TRACE_EVENT
> > macros. The softirq's TP_fast_assign uses softirq_to_name, and so that
> > array is needed to prepare the softirq's trace string.
> >
> > So, there's no explicit reference to the symbol in SystemTap -- it's
> > just indirectly referenced by the tracepoint declaration.
>
> TP_fast_assign should only be called by core code, it's the piece that
> copies the trace into the ring buffer. If systemtap copies events into
> the ring buffer from modular code something is deeply wrong in it's
> design.
In itself, the use of TRACE_EVENT from a module is fine, otherwise
Steve wouldn't have written the module support.
For example the mac80211 subsystem can be built as a module, and
if a tracing code is merged for this subsystem, we want it to be
usable whenever it is build as a module or not.
Frederic.
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