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Subject: Re: [RFC PATCH v2] Tracepoint: register/unregister struct tracepoint
From: Steven Rostedt <rostedt@goodmis.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>, linux-kernel@vger.kernel.org,
        Ingo Molnar <mingo@kernel.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Johannes Berg <johannes.berg@intel.com>
Date: Thu, 13 Mar 2014 14:17:53 -0400
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On Thu, 2014-03-13 at 16:54 +0000, Mathieu Desnoyers wrote:

> The other use-case is if the tracer has a module coming/going notifier
> tracking the module's tracepoint callsites. The going notifier should
> be run before the tracepoint.c going notifier. A notifier with negative
> priority should have this effect, since the tracepoint.c notifier has
> priority 0.
> 

The tracepoint should change to have two different notifiers that
represent one for coming and one for going (as ftrace does). The coming
one should have a priority of 0 (or INT_MIN (all other notifiers
dependent on this should have > 0)

The going notifier should have a INT_MAX to run after all other
tracepoint notifiers. (see kernel/trace/ftrace.c ftrace_module_enter_nb
and ftrace_module_exit_nb)

-- Steve