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authorAdrian Hunter <adrian.hunter@intel.com>2015-08-19 17:29:20 +0300
committerArnaldo Carvalho de Melo <acme@redhat.com>2015-08-19 14:15:25 -0300
commit5cb73340d92a716fd2776700742c3558206ae298 (patch)
treed0a04e74f6ae50c222f84bfd87aaa45d2391643e
parent0d7e7acc47133e82911e24758178815cfee309e9 (diff)
perf tools: Make fork event processing more resilient
When processing a fork event, the tools lookup the parent thread by its tid. In a couple of cases, it is possible for that thread to have the wrong pid. That can happen if the data is being processed out of order, or if the (fork) event that would have removed the erroneous thread was lost. Assume the latter case, print a dump message, remove the erroneous thread, create a new one with the correct pid, and keep going. Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Tested-by: Jiri Olsa <jolsa@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1439994561-27436-3-git-send-email-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
-rw-r--r--tools/perf/util/machine.c20
1 files changed, 18 insertions, 2 deletions
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 7ff682770fdb..f1a4c833121e 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1387,6 +1387,24 @@ int machine__process_fork_event(struct machine *machine, union perf_event *event
event->fork.ptid);
int err = 0;
+ if (dump_trace)
+ perf_event__fprintf_task(event, stdout);
+
+ /*
+ * There may be an existing thread that is not actually the parent,
+ * either because we are processing events out of order, or because the
+ * (fork) event that would have removed the thread was lost. Assume the
+ * latter case and continue on as best we can.
+ */
+ if (parent->pid_ != (pid_t)event->fork.ppid) {
+ dump_printf("removing erroneous parent thread %d/%d\n",
+ parent->pid_, parent->tid);
+ machine__remove_thread(machine, parent);
+ thread__put(parent);
+ parent = machine__findnew_thread(machine, event->fork.ppid,
+ event->fork.ptid);
+ }
+
/* if a thread currently exists for the thread id remove it */
if (thread != NULL) {
machine__remove_thread(machine, thread);
@@ -1395,8 +1413,6 @@ int machine__process_fork_event(struct machine *machine, union perf_event *event
thread = machine__findnew_thread(machine, event->fork.pid,
event->fork.tid);
- if (dump_trace)
- perf_event__fprintf_task(event, stdout);
if (thread == NULL || parent == NULL ||
thread__fork(thread, parent, sample->time) < 0) {