From: Ian Rogers irogers@google.com
commit f3bed55e850926614b9898fe982f66d2541a36a5 upstream.
Current logic yields the child task as the parent.
Before: $ perf record bash -c "perf list > /dev/null" $ perf script -D |grep 'FORK|EXIT' 4387036190981094 0x5a70 [0x30]: PERF_RECORD_FORK(10472:10472):(10470:10470) 4387036606207580 0xf050 [0x30]: PERF_RECORD_EXIT(10472:10472):(10472:10472) 4387036607103839 0x17150 [0x30]: PERF_RECORD_EXIT(10470:10470):(10470:10470) ^ Note the repeated values here -------------------/
After: 383281514043 0x9d8 [0x30]: PERF_RECORD_FORK(2268:2268):(2266:2266) 383442003996 0x2180 [0x30]: PERF_RECORD_EXIT(2268:2268):(2266:2266) 383451297778 0xb70 [0x30]: PERF_RECORD_EXIT(2266:2266):(2265:2265)
Fixes: 94d5d1b2d891 ("perf_counter: Report the cloning task as parent on perf_counter_fork()") Reported-by: KP Singh kpsingh@google.com Signed-off-by: Ian Rogers irogers@google.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Link: https://lkml.kernel.org/r/20200417182842.12522-1-irogers@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/events/core.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)
--- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6923,10 +6923,17 @@ static void perf_event_task_output(struc goto out;
task_event->event_id.pid = perf_event_pid(event, task); - task_event->event_id.ppid = perf_event_pid(event, current); - task_event->event_id.tid = perf_event_tid(event, task); - task_event->event_id.ptid = perf_event_tid(event, current); + + if (task_event->event_id.header.type == PERF_RECORD_EXIT) { + task_event->event_id.ppid = perf_event_pid(event, + task->real_parent); + task_event->event_id.ptid = perf_event_pid(event, + task->real_parent); + } else { /* PERF_RECORD_FORK */ + task_event->event_id.ppid = perf_event_pid(event, current); + task_event->event_id.ptid = perf_event_tid(event, current); + }
task_event->event_id.time = perf_event_clock(event);