perf synthetic-events: Ignore dead threads during event synthesis

When it synthesize various task events, it scans the list of task
first and then accesses later.  There's a window threads can die
between the two and proc entries may not be available.

Instead of bailing out, we can ignore that thread and move on.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20220701205458.985106-2-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index a068f42..84d17bd 100644 (file)
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -767,11 +767,12 @@ static int __event__synthesize_thread(union perf_event *comm_event,
                if (*end)
                        continue;
 
-               rc = -1;
+               /* some threads may exit just after scan, ignore it */
                if (perf_event__prepare_comm(comm_event, pid, _pid, machine,
                                             &tgid, &ppid, &kernel_thread) != 0)
-                       break;
+                       continue;
 
+               rc = -1;
                if (perf_event__synthesize_fork(tool, fork_event, _pid, tgid,
                                                ppid, process, machine) < 0)
                        break;