perf thread_map: Create dummy constructor out of open coded equivalent

Create a dummy thread_map, one that has just one entry and it is -1,
meaning 'all threads', as this ends up going down to perf_event_open().

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jean Pihet <jean.pihet@linaro.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-8av26cz8uxmbnihl5mmrygp9@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/thread_map.c

@@ -214,6 +214,17 @@ static struct thread_map *thread_map__new_by_pid_str(const char *pid_str)
 	goto out;
 }
 
+struct thread_map *thread_map__new_dummy(void)
+{
+	struct thread_map *threads = malloc(sizeof(*threads) + sizeof(pid_t));
+
+	if (threads != NULL) {
+		threads->map[0]	= -1;
+		threads->nr	= 1;
+	}
+	return threads;
+}
+
 static struct thread_map *thread_map__new_by_tid_str(const char *tid_str)
 {
 	struct thread_map *threads = NULL, *nt;
@@ -224,14 +235,8 @@ static struct thread_map *thread_map__new_by_tid_str(const char *tid_str)
 	struct strlist *slist;
 
 	/* perf-stat expects threads to be generated even if tid not given */
-	if (!tid_str) {
-		threads = malloc(sizeof(*threads) + sizeof(pid_t));
-		if (threads != NULL) {
-			threads->map[0] = -1;
-			threads->nr	= 1;
-		}
-		return threads;
-	}
+	if (!tid_str)
+		return thread_map__new_dummy();
 
 	slist = strlist__new(false, tid_str);
 	if (!slist)

tools/perf/util/thread_map.h

@@ -9,6 +9,7 @@ struct thread_map {
 	pid_t map[];
 };
 
+struct thread_map *thread_map__new_dummy(void);
 struct thread_map *thread_map__new_by_pid(pid_t pid);
 struct thread_map *thread_map__new_by_tid(pid_t tid);
 struct thread_map *thread_map__new_by_uid(uid_t uid);