perf db-export: Export main_thread in db_export__sample()

Export main_thread in db_export__sample() because it makes the code
easier to understand, and prepares db_export__thread() for further
simplification.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/20190710085810.1650-5-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/db-export.c b/tools/perf/util/db-export.c
index 1450123..63f9edf 100644 (file)
--- a/tools/perf/util/db-export.c
+++ b/tools/perf/util/db-export.c
@@ -71,16 +71,10 @@ int db_export__thread(struct db_export *dbe, struct thread *thread,
        thread->db_id = ++dbe->thread_last_db_id;
 
        if (main_thread) {
-               if (main_thread != thread) {
-                       err = db_export__thread(dbe, main_thread, machine,
-                                               comm, main_thread);
+               if (main_thread != thread && comm) {
+                       err = db_export__comm_thread(dbe, comm, thread);
                        if (err)
                                return err;
-                       if (comm) {
-                               err = db_export__comm_thread(dbe, comm, thread);
-                               if (err)
-                                       return err;
-                       }
                }
                main_thread_db_id = main_thread->db_id;
        }
@@ -308,12 +302,24 @@ int db_export__sample(struct db_export *dbe, union perf_event *event,
                return err;
 
        main_thread = thread__main_thread(al->machine, thread);
-       if (main_thread)
+       if (main_thread) {
                comm = machine__thread_exec_comm(al->machine, main_thread);
+               /*
+                * A thread has a reference to the main thread, so export the
+                * main thread first.
+                */
+               err = db_export__thread(dbe, main_thread, al->machine, comm,
+                                       main_thread);
+               if (err)
+                       goto out_put;
+       }
 
-       err = db_export__thread(dbe, thread, al->machine, comm, main_thread);
-       if (err)
-               goto out_put;
+       if (thread != main_thread) {
+               err = db_export__thread(dbe, thread, al->machine, comm,
+                                       main_thread);
+               if (err)
+                       goto out_put;
+       }
 
        if (comm) {
                err = db_export__exec_comm(dbe, comm, main_thread);