From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752141AbbHRJJ5 (ORCPT ); Tue, 18 Aug 2015 05:09:57 -0400 Received: from mga14.intel.com ([192.55.52.115]:46276 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751594AbbHRJJz (ORCPT ); Tue, 18 Aug 2015 05:09:55 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.15,700,1432623600"; d="scan'208";a="750705571" From: Adrian Hunter To: Arnaldo Carvalho de Melo Cc: linux-kernel@vger.kernel.org, Jiri Olsa Subject: [PATCH] perf tools: Fix use of wrong event when processing exit events Date: Tue, 18 Aug 2015 12:07:05 +0300 Message-Id: <1439888825-27708-1-git-send-email-adrian.hunter@intel.com> X-Mailer: git-send-email 1.9.1 Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- tools/perf/builtin-script.c | 4 ++-- tools/perf/util/intel-bts.c | 2 +- tools/perf/util/intel-pt.c | 2 +- 3 files changed, 4 insertions(+), 4 deletions(-) diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c index 105332e950a9..17030c6c64b6 100644 --- a/tools/perf/builtin-script.c +++ b/tools/perf/builtin-script.c @@ -739,8 +739,8 @@ 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 dce99cfb1309..09d142b362fa 100644 --- 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 2a4a4120473b..ef2fb13f1dfa 100644 --- a/tools/perf/util/intel-pt.c +++ b/tools/perf/util/intel-pt.c @@ -1464,7 +1464,7 @@ 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) { -- 1.9.1