perf tools: Fix use of wrong event when processing exit events

In a couple of cases the 'comm' member of 'union event' has been used
instead of the correct member ('fork') when processing exit events.

In the cases where it has been used incorrectly, only the 'pid' and
'tid' are affected.  The 'pid' value would be correct anyway because it
is in the same position in 'comm' and 'fork' events, but the 'tid' would
have been incorrectly assigned from 'ppid'.

However, for exit events, the kernel puts the current task in the 'ppid'
and 'ttid' which is the same as the exiting task.  That is 'ppid' ==
'pid' and if the task is not multi-threaded, 'pid' == 'tid' i.e. the
data goes wrong only when tracing multi-threaded programs.

It is hard to find an example of how this would produce an error in
practice.  There are 3 occurences of the fix:

1. perf script is only affected if !sample_id_all which only happens on
  old kernels.

2. intel_pt is only affected when decoding without timestamps
   and would probably still decode correctly - the exit event is
   only used to flush out data which anyway gets flushed at the
   end of the session

3. intel_bts also uses the exit event to flush data which
   would probably not cause errors as it would get flushed at
   the end of the session instead

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1439888825-27708-1-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index eb51325e8ad99adefa7671a7b511626b7c136d1d..284a76e046284983cd769da89cb45604b114a41a 100644 (file)
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -768,8 +768,8 @@ static int process_exit_event(struct perf_tool *tool,
        if (!evsel->attr.sample_id_all) {
                sample->cpu = 0;
                sample->time = 0;
-               sample->tid = event->comm.tid;
-               sample->pid = event->comm.pid;
+               sample->tid = event->fork.tid;
+               sample->pid = event->fork.pid;
        }
        print_sample_start(sample, thread, evsel);
        perf_event__fprintf(event, stdout);

diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c
index ea768625ab5b39eaf8ce59059e10349eb7ecd34a..eb0e7f8bf5158c98c95216d4fb9d3eb96568c50b 100644 (file)
--- a/tools/perf/util/intel-bts.c
+++ b/tools/perf/util/intel-bts.c
@@ -623,7 +623,7 @@ static int intel_bts_process_event(struct perf_session *session,
        if (err)
                return err;
        if (event->header.type == PERF_RECORD_EXIT) {
-               err = intel_bts_process_tid_exit(bts, event->comm.tid);
+               err = intel_bts_process_tid_exit(bts, event->fork.tid);
                if (err)
                        return err;
        }

diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index bb41c20e6005e1a2d986656fc94eead62de7a4ee..535d86f8e4d17b802a4c0473a7bf7ff937a10b15 100644 (file)
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -1494,7 +1494,7 @@ static int intel_pt_process_event(struct perf_session *session,
        if (pt->timeless_decoding) {
                if (event->header.type == PERF_RECORD_EXIT) {
                        err = intel_pt_process_timeless_queues(pt,
-                                                              event->comm.tid,
+                                                              event->fork.tid,
                                                               sample->time);
                }
        } else if (timestamp) {