perf events: Tidy up perf_event__preprocess_sample

Use local variable 'dso' to reduce typing a bit and rearrange the if
condition. Also NULL check of al->map in the condition is not necessary.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1323703017-6060-7-git-send-email-namhyung@gmail.com
Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/event.c

@@ -814,13 +814,14 @@ int perf_event__preprocess_sample(const union perf_event *event,
 	al->cpu = sample->cpu;
 
 	if (al->map) {
+		struct dso *dso = al->map->dso;
+
 		if (symbol_conf.dso_list &&
-		    (!al->map || !al->map->dso ||
-		     !(strlist__has_entry(symbol_conf.dso_list,
-					  al->map->dso->short_name) ||
-		       (al->map->dso->short_name != al->map->dso->long_name &&
-			strlist__has_entry(symbol_conf.dso_list,
-					   al->map->dso->long_name)))))
+		    (!dso || !(strlist__has_entry(symbol_conf.dso_list,
+						  dso->short_name) ||
+			       (dso->short_name != dso->long_name &&
+				strlist__has_entry(symbol_conf.dso_list,
+						   dso->long_name)))))
 			goto out_filtered;
 
 		al->sym = map__find_symbol(al->map, al->addr, filter);