On Wed, 8 Apr 2026 10:15:00 +0800 Pengpeng Hou <[email protected]> wrote:
> Hi Steve, > > Thanks for looking at this. > > I believe this path is reachable. > > field->system is set when a VAR_REF is created with an event-qualified > reference. The assignment happens in init_var_ref(), which is called > from create_var_ref(). > > The parser accepts fully qualified references of the form > > system.event.$var > > and parse_expr() passes the parsed system/event strings into > create_var_ref(). trace_action_create() also accepts explicitly > qualified action parameters in the same form and passes those strings > into create_var_ref(). > > This is also documented in Documentation/trace/histogram.rst: > > fully-qualified name is of the form 'system.event_name.$var_name' > or 'system.event_name.field'. Ah I read the document and missed this part. Thanks for pointing it out. None of our tests use this, so that definitely needs to be fixed. OK, yeah I can trigger that path now. I'll continue looking at the patch. Thanks, -- Steve > > The path is user-visible because reading back the trigger goes through > > event_hist_trigger_print() -> hist_field_print() -> hist_field_name() > > so creating a hist trigger that uses an inter-event variable reference > in fully qualified form is enough to exercise it. > > So I don't think this is dead code. If you would prefer a different way > of handling the printed name, I can respin accordingly, but I don't > think the current branch is unreachable. > > Thanks, > Pengpeng >
