perf tools: Make fork event processing more resilient

[linux.git] / tools / perf / util / machine.c

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 7ff682770fdb16e71b368af16efad0edd9443d87..f1a4c833121e306a364851328f6409cb22d779eb 100644 (file)
--- 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) {