perf tools: Try to lookup kernel module map before creating one

Currently we assume machine__new_module is called only once for each
module so we create its map&dso unconditionally.

However it's possible that it's called multiple times for same module.
Like for perf record:

  1) via machine__create_module during machine init
  2) via kernel MMAP event processing

Trying to lookup kernel module map before creating one.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-kx76xfqpnrpho5hdaapbqm09@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/machine.c

@@ -498,6 +498,11 @@ struct map *machine__new_module(struct machine *machine, u64 start,
 	if (kmod_path__parse_name(&m, filename))
 		return NULL;
 
+	map = map_groups__find_by_name(&machine->kmaps, MAP__FUNCTION,
+				       m.name);
+	if (map)
+		goto out;
+
 	dso = machine__module_dso(machine, &m, filename);
 	if (dso == NULL)
 		goto out;