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

[Arnaldo Carvalho de Melo <acme@redhat.com>]

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]$

- Arnaldo