Re: [External] Re: [RFC 02/12] perf event action: Add parsing const expr support

Yang Jihong
2024-12-04T08:29:16Z

Hello,

On 11/29/24 04:23, Arnaldo Carvalho de Melo wrote:
> On Thu, Nov 28, 2024 at 09:35:43PM +0800, Yang Jihong wrote:
>> Event action requires constant expression parsing support,
>> which include constant integer and constant string.
>>
>> Signed-off-by: Yang Jihong <yangjihong@bytedance.com>
>> ---
>> tools/perf/util/parse-action.c | 27 +++++++++++++++++++++++++++
>> tools/perf/util/parse-action.h | 5 +++++
>> 2 files changed, 32 insertions(+)
>>
>> diff --git a/tools/perf/util/parse-action.c b/tools/perf/util/parse-action.c
>> index 01c8c7fdea59..391546bf3d73 100644
>> --- a/tools/perf/util/parse-action.c
>> +++ b/tools/perf/util/parse-action.c
>> @@ -4,6 +4,9 @@
>> * Actions are the programs that run when the sampling event is triggered.
>> * The action is a list of expressions separated by semicolons (;).
>> * Each action is an expression, added to actions_head node as list_head node.
>> + *
>> + * Supported expressions:
>> + * - constant:
>
> This seems incomplete, what should come after the :?
>
> the patch description, at the beginning of this message has more details
> than here.
This patch only implements a general constant expression category. The
next patch will support parsing of specific string constant expressions
and integer constant expressions.

>
>> */
>>
>> #include "util/debug.h"
>> @@ -115,7 +118,31 @@ void event_actions__free(void)
>> (void)event_actions__for_each_expr_safe(do_action_free, NULL, false);
>> }
>>
>> +static struct evtact_expr_ops *expr_const_ops_list[EVTACT_EXPR_CONST_TYPE_MAX] = {
>> +};
>> +
>> +static int expr_const_set_ops(struct evtact_expr *expr, u32 opcode)
>> +{
>> + if (opcode >= EVTACT_EXPR_CONST_TYPE_MAX) {
>> + pr_err("expr_const opcode invalid: %u\n", opcode);
>> + return -EINVAL;
>> + }
>> +
>> + if (expr_const_ops_list[opcode] == NULL) {
>> + pr_err("expr_const opcode not supported: %u\n", opcode);
>> + return -ENOTSUP;
>> + }
>
> Since expr_const_ops_list[EVTACT_EXPR_TYPE_CONST] is NULL, this will
> always fail?
>
Yes, this patch does not support specific constant expressions, so it is
empty.

Thanks,
Yang.