Re: [PATCH tip 1/1] tracing: handle unregistering the current tracer

[Ingo Molnar <mingo@elte.hu>]

* Arnaldo Carvalho de Melo <acme@redhat.com> wrote:

> Em Mon, Feb 09, 2009 at 10:58:16AM +0100, Ingo Molnar escreveu:
> > 
> > * Arnaldo Carvalho de Melo <acme@redhat.com> wrote:
> > 
> > > Impact: simplification
> > > 
> > > Instead of requiring that plugins have the sequence:
> > > 
> > >   my_tracer_stop(my_trace_array);
> > >   unregister_tracer(my_tracer);
> > > 
> > > it should be possible just do a:
> > > 
> > >   unregister_tracer(my_tracer);
> > > 
> > > Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> > > ---
> > >  kernel/trace/trace.c |    9 +++++++++
> > >  1 files changed, 9 insertions(+), 0 deletions(-)
> > 
> > Applied to tip/tracing/ftrace, thanks Arnaldo!
> > 
> > Nice one - we should try to shoot for the smallest physically
> > possible linecount for any new (possibly trivial) tracer plugin.
> 
> That and also for as few as possible EXPORT_SYMBOL_GPL entries, now, for
> converting net/ipv4/tcp_probe.c to an ftrace plugin + one tracepoint at
> tcp_rcv_established we need:
> 
> doppio linux-2.6-tip]$ grep ^+EXPORT_SYMBOL ~/tcp_cwnd_tracer.patch 
> +EXPORT_SYMBOL_GPL(register_tracer);
> +EXPORT_SYMBOL_GPL(unregister_tracer);
> +EXPORT_SYMBOL_GPL(tracing_record_cmdline);
> +EXPORT_SYMBOL_GPL(trace_buffer_lock_reserve);
> +EXPORT_SYMBOL_GPL(trace_buffer_unlock_commit);
> +EXPORT_SYMBOL_GPL(trace_seq_printf);
> +EXPORT_SYMBOL_GPL(register_ftrace_event);
> +EXPORT_SYMBOL_GPL(unregister_ftrace_event);
> [acme@doppio linux-2.6-tip]$

ok. For in-kernel plugins it's of course fine to do those exports in any case.

	Ingo