Re: [PATCH] tracing/profile: Fix profile_disable vs module_unload

From: Peter Zijlstra
Date: Thu Aug 27 2009 - 12:05:43 EST


On Thu, 2009-08-27 at 11:57 -0400, Steven Rostedt wrote:
> On Thu, 27 Aug 2009, Peter Zijlstra wrote:
>
> > On Wed, 2009-08-26 at 15:48 -0400, Steven Rostedt wrote:
> > > \
> > > @@ -399,16 +413,20 @@ static int ftrace_profile_enable_##call(struct ftrace_event_call *event_call) \
> > > { \
> > > int ret = 0; \
> > > \
> > > - if (!atomic_inc_return(&event_call->profile_count)) \
> > > + if (!atomic_inc_return(&event_call->profile_count)) { \
> > > + event_trace_up_ref(); \
> > > ret = register_trace_##call(ftrace_profile_##call); \
> > > + } \
> > > \
> > > return ret; \
> > > } \
> > > \
> > > static void ftrace_profile_disable_##call(struct ftrace_event_call *event_call)\
> > > { \
> > > - if (atomic_add_negative(-1, &event_call->profile_count)) \
> > > + if (atomic_add_negative(-1, &event_call->profile_count)) { \
> > > unregister_trace_##call(ftrace_profile_##call); \
> > > + event_trace_down_ref(); \
> > > + } \
> > > }
> >
> > Ha, almost, make that {un,}register_ftrace_##call() and stick the module
> > gunk in there, and I'm ok.
>
> Peter, that {un,}register_tace_##call is the tracepoint code. The
> DEFINE_TRACE creates those functions. This is the lowest level we can go
> in the ftrace.h file.

Did you miss the extra f?

You can wrap the regular {un,}register_trace_##call() things in
{un,}register_/F/trace_##call() functions which also take care of the
module stuff.

Your patch is virtually identical to the one that started this thread,
everybody using the TRACE_EVENT() things will still need to worry about
modules.
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