Messages in this thread | | | Subject | Re: Unresolved reference for histogram variable | From | Tom Zanussi <> | Date | Thu, 16 Jan 2020 22:26:16 -0600 |
| |
Hi Steve,
On Thu, 2020-01-16 at 16:56 -0500, Steven Rostedt wrote: > On Thu, 16 Jan 2020 15:42:16 -0500 > Steven Rostedt <rostedt@goodmis.org> wrote: > > > in parse_expr(): > > > > operand1->read_once = true; > > operand2->read_once = true; > > > > Why is that? > > > > This means that any variable used in an expression can not be use > > later > > on. > > > > Or should the variable be detected that it is used multiple times > > in > > the expression, and have the parser detect this, and just reuse the > > same variable multiple times? > > This patch seems to fix the problem, and lets us reuse the same > variable multiple times.
It works for me too, and seems like it should be a good fix for the problem. The size and is_signed might be the overkill you're referring to, but I'd like to spend time tomorrow verifying that and doing some testing to make sure.
Thanks,
Tom
> > -- Steve > > diff --git a/kernel/trace/trace_events_hist.c > b/kernel/trace/trace_events_hist.c > index 117a1202a6b9..b7f944735a4a 100644 > --- a/kernel/trace/trace_events_hist.c > +++ b/kernel/trace/trace_events_hist.c > @@ -116,6 +116,7 @@ struct hist_field { > struct ftrace_event_field *field; > unsigned long flags; > hist_field_fn_t fn; > + unsigned int ref; > unsigned int size; > unsigned int offset; > unsigned int is_signed; > @@ -2432,8 +2433,16 @@ static int contains_operator(char *str) > return field_op; > } > > +static void get_hist_field(struct hist_field *hist_field) > +{ > + hist_field->ref++; > +} > + > static void __destroy_hist_field(struct hist_field *hist_field) > { > + if (--hist_field->ref > 1) > + return; > + > kfree(hist_field->var.name); > kfree(hist_field->name); > kfree(hist_field->type); > @@ -2475,6 +2484,8 @@ static struct hist_field > *create_hist_field(struct hist_trigger_data *hist_data, > if (!hist_field) > return NULL; > > + hist_field->ref = 1; > + > hist_field->hist_data = hist_data; > > if (flags & HIST_FIELD_FL_EXPR || flags & > HIST_FIELD_FL_ALIAS) > @@ -2670,6 +2681,19 @@ static struct hist_field > *create_var_ref(struct hist_trigger_data *hist_data, > { > unsigned long flags = HIST_FIELD_FL_VAR_REF; > struct hist_field *ref_field; > + int i; > + > + for (i = 0; i < hist_data->n_var_refs; i++) { > + ref_field = hist_data->var_refs[i]; > + /* Maybe this is overkill? */ > + if (ref_field->var.idx == var_field->var.idx && > + ref_field->var.hist_data == var_field->hist_data > && > + ref_field->size == var_field->size && > + ref_field->is_signed == var_field->is_signed) { > + get_hist_field(ref_field); > + return ref_field; > + } > + } > > ref_field = create_hist_field(var_field->hist_data, NULL, > flags, NULL); > if (ref_field) {
| |