Re: [PATCH v2 2/6] perf test: Handle metric reuse in pmu-events parsing test

[John Garry]

On 06/04/2021 13:17, Jiri Olsa wrote:
+                       ref = &metric->metric_ref;
+                       ref->metric_name = pe->metric_name;
+                       ref->metric_expr = pe->metric_expr;
+                       list_add_tail(&metric->list, compound_list);
+
+                       rc = expr__find_other(pe->metric_expr, NULL, pctx, 0);
Hi Jirka,
so this might add new items to pctx->ids, I think you need
to restart the iteration as we do it in __resolve_metric
otherwise you could miss some new keys
I thought that I was doing this. Indeed, this code is very much like
__resolve_metric();)

So expr__find_other() may add a new item to pctx->ids, and we always iterate
again, and try to lookup any pmu_events, *, above. If none exist, then we
hm, I don't see that.. so, what you do is:

        hashmap__for_each_entry_safe((&pctx->ids) ....) {

                rc = expr__find_other(pe->metric_expr, NULL, pctx, 0);
        }

and what I think we need to do is:

        hashmap__for_each_entry_safe((&pctx->ids) ....) {

                rc = expr__find_other(pe->metric_expr, NULL, pctx, 0);

                break;  
        }

each time you resolve another metric, you need to restart
the pctx->ids iteration, because there will be new items,
and we are in the middle of it

Sure, but we will restart anyway.

Regardless of this, I don't think what I am doing is safe, i.e. adding 
new items in the middle of the iter, so I will change in the way you 
suggest.

Thanks,
John