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SubjectRe: [PATCH v6 1/4] tools/perf: support parsing parameterized events
On Mon, Dec 22, 2014 at 11:30:45AM -0800, Sukadev Bhattiprolu wrote:
> Jiri Olsa [jolsa@redhat.com] wrote:
> | On Sun, Dec 21, 2014 at 11:49:24PM -0800, Sukadev Bhattiprolu wrote:
> |
> | SNIP
> |
> | > + }
> | >
> | > switch (format->value) {
> | > case PERF_PMU_FORMAT_VALUE_CONFIG:
> | > @@ -592,11 +629,16 @@ static int pmu_config_term(struct list_head *formats,
> | > }
> | >
> | > /*
> | > - * XXX If we ever decide to go with string values for
> | > - * non-hardcoded terms, here's the place to translate
> | > - * them into value.
> | > + * Either directly use a numeric term, or try to translate string terms
> | > + * using event parameters.
> | > */
> | > - pmu_format_value(format->bits, term->val.num, vp, zero);
> | > + if (term->type_val == PARSE_EVENTS__TERM_TYPE_NUM)
> | > + val = term->val.num;
> | > + else
> | > + if (pmu_resolve_param_term(term, head_terms, &val))
> | > + return -EINVAL;
> | > +
> |
> | I'm ok with the change logic, but I'm missing here check for the 'term'
> | string value to be '?', so we force subst terms to have '?' as value..
> | I believe thats what we decided in the previous set discussion, right?
>
> The =? is not a user input, so I did not think of validating that.
>
> perf tool expects kernel/sysfs to show entries like 'core=?'. Are you
> saying that we should error out if kernel mistakenly displays 'core=$val'
> or 'core=?val' ?

I think the we should at least try to have interface unambiguous
from the beginning

> If a required parameter is missing, we catch that in pmu_resolve_param_term().
> If a bogus parameter is specified we catch that above in pmu_config_term().

but the value of that param is unspecified, and if we later want to
add another type of string values we would be screwed.. as I described
in the previous reply for your other patch.

jirka


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