Re: [PATCH 3/3] perf tools: Put Python bytecode in output directory

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] The use of `PYTHONPYCACHEPREFIX` fails to resolve out-of-tree build pollution for Python 3.6 and 3.7.
- [Low] The newly configured relocated Python bytecode cache directory (`$(OUTPUT)/__pycache__`) is not removed during `make clean` or `make python-clean`.
--

commit 7f6b9146d44a693c3114eaae7826841344f49ebd
Author: Ben Hutchings <benh@debian.org>

perf tools: Put Python bytecode in output directory

This commit sets PYTHONPYCACHEPREFIX during perf tool builds when an output
directory is specified. This aims to prevent Python from writing bytecode
into the source tree during out-of-tree builds.

> diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
> --- a/tools/perf/Makefile.perf
> +++ b/tools/perf/Makefile.perf
> @@ -399,6 +399,11 @@ PYTHON_EXTBUILD_LIB := $(PYTHON_EXTBUILD)lib/
>  PYTHON_EXTBUILD_TMP := $(PYTHON_EXTBUILD)tmp/
>  export PYTHON_EXTBUILD_LIB PYTHON_EXTBUILD_TMP
>  
> +# Put Python bytecode in output directory
> +ifdef OUTPUT
> +export PYTHONPYCACHEPREFIX := $(OUTPUT)/__pycache__

[Severity: Medium]
Since the perf build system explicitly supports Python 3.6 and 3.7, does
setting PYTHONPYCACHEPREFIX resolve the out-of-tree build pollution for
those versions?

This environment variable was introduced in Python 3.8 and is silently
ignored in earlier versions. Would exporting PYTHONDONTWRITEBYTECODE=1 be a
more universally supported alternative?

> +endif
> +
>  python-clean := $(call QUIET_CLEAN, python) $(RM) -r $(PYTHON_EXTBUILD) $(OUTPUT)python/perf*.so

[Severity: Low]
Does the newly configured relocated Python bytecode cache directory need to
be explicitly removed in the python-clean target?

The existing clean rules do not match the deep absolute paths created by
PYTHONPYCACHEPREFIX, which leaves the entire __pycache__ directory hierarchy
orphaned in the build output after a make clean.

>  # Use the detected configuration

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/ag8X7gcDw6jpJsLq@decadent.org.uk?part=3