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Subject[PATCH] perf tools: Fix ppid for non-main thread
Date
Commit ca6c41c59b9 sets the ppid based on what is read from the
/proc/pid/status file when synthesizing fork events. This is correct
thing to do for new processes but not threads of a process. Fix
ppid for threads to be the main thread when synthesizing fork events
(ie., assume main thread spawned all sub-threads in a process).

Reported-by: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Signed-off-by: David Ahern <david.ahern@oracle.com>
Cc: Don Zickus <dzickus@redhat.com>
---
tools/perf/util/event.c | 14 ++++++++++++--
1 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 186929a..ff866c4 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -183,8 +183,18 @@ static int perf_event__synthesize_fork(struct perf_tool *tool,
{
memset(&event->fork, 0, sizeof(event->fork) + machine->id_hdr_size);

- event->fork.ppid = ppid;
- event->fork.ptid = ppid;
+ /*
+ * for main thread set parent to ppid from status file. For other
+ * threads set parent pid to main thread. ie., assume main thread
+ * spawns all threads in a process
+ */
+ if (tgid == pid) {
+ event->fork.ppid = ppid;
+ event->fork.ptid = ppid;
+ } else {
+ event->fork.ppid = tgid;
+ event->fork.ptid = tgid;
+ }
event->fork.pid = tgid;
event->fork.tid = pid;
event->fork.header.type = PERF_RECORD_FORK;
--
1.7.1


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