Re: [PATCH 01/10] perf jevents: Store raw bytes in BigCString instead of C-escaped strings

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential
issue to consider:
- [Medium] perf jevents: incompatible pmu_name redefinition breaks mypy
  build
--

commit cec20814c29173c92160614f78f6888af106102a
Author: Ian Rogers <irogers@google.com>

perf jevents: Store raw bytes in BigCString instead of C-escaped strings

This commit changes BigCString and _metricgroups to store raw NUL-delimited
UTF-8 bytes instead of C-escaped strings, escaping them into C string
literals only when emitting C source.

> diff --git a/tools/perf/pmu-events/jevents.py b/tools/perf/pmu-events/jevents.py
> index 080e04b51b8c5..0721c8b2551c3 100755
> --- a/tools/perf/pmu-events/jevents.py
> +++ b/tools/perf/pmu-events/jevents.py

[ ... ]

> @@ -556,11 +550,12 @@ def print_pending_events() -> None:
>  static const struct pmu_table_entry {_pending_events_tblname}[] = {{
>  """)
>    for (pmu, tbl_pmu) in sorted(pmus):
> -    pmu_name = f"{pmu}\\000"
> +    pmu_name = (pmu + '\0').encode('utf-8')
> +    pmu_comment = bytes_to_c_literal(pmu_name).replace('*/', r'\*\/')
>      _args.output_file.write(f"""\t{{
>  \t\t.entries = {_pending_events_tblname}_{tbl_pmu},
>  \t\t.num_entries = ARRAY_SIZE({_pending_events_tblname}_{tbl_pmu}),
> -\t\t.pmu_name = {{ {_bcs.offsets[pmu_name]} /* {pmu_name} */ }},
> +\t\t.pmu_name = {{ {_bcs.offsets[pmu_name]} /* {pmu_comment} */ }},
>  \t}},
>  """)
>    _args.output_file.write('};\n\n')
> @@ -612,11 +607,12 @@ def print_pending_metrics() -> None:
>  static const struct pmu_table_entry {_pending_metrics_tblname}[] = {{
>  """)
>    for (pmu, tbl_pmu) in sorted(pmus):
> -    pmu_name = f"{pmu}\\000"
> +    pmu_name = (pmu + '\0').encode('utf-8')
> +    pmu_comment = bytes_to_c_literal(pmu_name).replace('*/', r'\*\/')
>      _args.output_file.write(f"""\t{{
>  \t\t.entries = {_pending_metrics_tblname}_{tbl_pmu},
>  \t\t.num_entries = ARRAY_SIZE({_pending_metrics_tblname}_{tbl_pmu}),
> -\t\t.pmu_name = {{ {_bcs.offsets[pmu_name]} /* {pmu_name} */ }},
> +\t\t.pmu_name = {{ {_bcs.offsets[pmu_name]} /* {pmu_comment} */ }},
>  \t}},
>  """)
>    _args.output_file.write('};\n\n')

[Severity: Medium]
Does reassigning bytes to pmu_name in print_pending_events() and
print_pending_metrics() break the default mypy build target?

Earlier in both functions, pmu_name is assigned a str value:

tools/perf/pmu-events/jevents.py:print_pending_events() {
    ...
      pmu_name = event.pmu.replace(',', '_')
    ...
}

Rebinding pmu_name to bytes and passing it to bytes_to_c_literal() and
_bcs.offsets[] causes mypy to fail with incompatible assignment, argument
type, and index type errors, breaking git bisect until the later commit
"perf jevents: Store PMU names as string literals in struct
pmu_table_entry" removes these assignments.  Using a separate variable name
such as pmu_name_bytes (like mgroup_bytes in preprocess_one_file()) avoids
the type conflict.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261113210822.3112700-1-irogers@google.com?part=1