From: Masami Hiramatsu <[email protected]> Call traceoff trigger after the event is recorded. Since current traceoff trigger is called before recording the event, we can not know what event stopped tracing.
Typical usecase of traceoff/traceon trigger is tracing function calls and trace events between a pair of events. For example, trace function calls between syscall entry/exit. In that case, it is useful if we can see the return code of the target syscall. Link: http://lkml.kernel.org/r/147335074530.12462.4526186083406015005.stgit@devbox Signed-off-by: Masami Hiramatsu <[email protected]> Signed-off-by: Steven Rostedt <[email protected]> --- kernel/trace/trace_events_trigger.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c index a975571cde24..6721a1e89f39 100644 --- a/kernel/trace/trace_events_trigger.c +++ b/kernel/trace/trace_events_trigger.c @@ -1028,6 +1028,7 @@ static struct event_command trigger_traceon_cmd = { static struct event_command trigger_traceoff_cmd = { .name = "traceoff", .trigger_type = ETT_TRACE_ONOFF, + .flags = EVENT_CMD_FL_POST_TRIGGER, .func = event_trigger_callback, .reg = register_trigger, .unreg = unregister_trigger, -- 2.8.1
