[PATCH v1] perf python: Clean up and restructure setup.py

[PATCH v1] perf python: Clean up and restructure setup.py

[Ian Rogers]

Clean up and restructure the python setup script to resolve pylint
warnings, improve code quality, and increase robustness and
readability, targeting Python 3.9+ (the Linux kernel build minimum
Python version).

Changes:
- Restructure the script to use a `main()` function as the entry point,
  leaving only imports, classes, and pure functions at module level.
- Eliminate all global/module-level variables, making them local to
  `main()` or the respective classes/functions.
- Make `clang_has_option` a pure function by passing all necessary
  parameters explicitly.
- Extract clang compiler flag filtering into a new
  `filter_clang_options` helper function. This function uses a loop
  over a tuple of options, replacing ~30 lines of repetitive blocks
  and reducing branch/statement complexity in the main flow.
- Cleanly define attributes in `__init__` for `BuildExt` and `InstallLib`
  and read environment variables dynamically within the methods, removing
  their dependency on global variables.
- Replace legacy Popen with subprocess.run for safer process handling.
- Use list-based flag filtering (split, filter, re-join) instead of regex
  `re.sub` substitutions on space-separated compiler flag strings. This
  avoids boundary bugs and safely handles flags with arguments (e.g.
  `-fcf-protection=full`).
- Safely parse `CC` env var using `shlex.split` to handle quotes and pass
  compiler arguments as `list[str]` lists to helper functions, avoiding
  redundant string formatting and parsing.
- Remove unused `import re`.
- Rename setuptools command subclasses to PascalCase (BuildExt, InstallLib).
- Add type annotations to functions and methods.
- Add missing docstrings for module, functions, and classes.
- Split long lines to adhere to standard limits.

Assisted-by: Antigravity:gemini-3.5-flash
Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/setup.py | 253 +++++++++++++++++++++++++--------------
 1 file changed, 166 insertions(+), 87 deletions(-)

diff --git a/tools/perf/util/setup.py b/tools/perf/util/setup.py
index b65b1792ca05..55ff7d8cba7e 100644
--- a/tools/perf/util/setup.py
+++ b/tools/perf/util/setup.py
@@ -1,108 +1,187 @@
-from os import getenv, path
-from subprocess import Popen, PIPE
-from re import sub
+"""Setup script for perf python extension.
+
+This script is used to build and install the perf python binding.
+It handles compiler-specific flags, especially for clang, and configures
+the setuptools Extension.
+"""
+
+import os
 import shlex
+import subprocess
+import sysconfig
 
-cc = getenv("CC")
-assert cc, "Environment variable CC not set"
+from setuptools import setup, Extension
+from setuptools.command.build_ext import build_ext as _build_ext
+from setuptools.command.install_lib import install_lib as _install_lib
 
-# Check if CC has options, as is the case in yocto, where it uses CC="cc --sysroot..."
-cc_tokens = cc.split()
-if len(cc_tokens) > 1:
-    cc = cc_tokens[0]
-    cc_options = " ".join([str(e) for e in cc_tokens[1:]]) + " "
-else:
-    cc_options = ""
 
-# ignore optional stderr could be None as it is set to PIPE to avoid that.
-# mypy: disable-error-code="union-attr"
-cc_is_clang = b"clang version" in Popen([cc, "-v"], stderr=PIPE).stderr.readline()
+def clang_has_option(cc: str, cc_args: list[str], src_feature_tests: str, option: str) -> bool:
+    """Check if clang supports a specific option.
 
-srctree = getenv('srctree')
-assert srctree, "Environment variable srctree, for the Linux sources, not set"
-src_feature_tests  = f'{srctree}/tools/build/feature'
+    Args:
+        cc: The compiler executable.
+        cc_args: Compiler arguments from CC environment variable.
+        src_feature_tests: Path to the feature tests directory.
+        option: The compiler option to check (e.g., "-mcet").
 
-def clang_has_option(option):
+    Returns:
+        True if the option is supported, False otherwise.
+    """
     error_substrings = (
         b"unknown argument",
         b"is not supported",
         b"unknown warning option"
     )
-    cmd = shlex.split(f"{cc} {cc_options} {option}") + [
+    cmd = [cc] + cc_args + [
+        option,
         "-o", "/dev/null",
-        path.join(src_feature_tests, "test-hello.c")
+        os.path.join(src_feature_tests, "test-hello.c")
     ]
-    cc_output = Popen(cmd, stderr=PIPE).stderr.readlines()
+    try:
+        res = subprocess.run(cmd, stderr=subprocess.PIPE, stdout=subprocess.DEVNULL, check=False)
+        cc_output = res.stderr.splitlines()
+    except OSError:
+        return False
     return not any(any(error in line for error in error_substrings) for line in cc_output)
 
-if cc_is_clang:
-    from sysconfig import get_config_vars
-    vars = get_config_vars()
+
+def filter_clang_options(cc: str, cc_args: list[str], src_feature_tests: str) -> None:
+    """Filter out unsupported clang options from sysconfig CFLAGS and OPT.
+
+    Args:
+        cc: The compiler executable.
+        cc_args: Compiler arguments from CC environment variable.
+        src_feature_tests: Path to the feature tests directory.
+    """
+    config_vars = sysconfig.get_config_vars()
     for var in ('CFLAGS', 'OPT'):
-        vars[var] = sub("-specs=[^ ]+", "", vars[var])
-        if not clang_has_option("-mcet"):
-            vars[var] = sub("-mcet", "", vars[var])
-        if not clang_has_option("-fcf-protection"):
-            vars[var] = sub("-fcf-protection", "", vars[var])
-        if not clang_has_option("-fstack-clash-protection"):
-            vars[var] = sub("-fstack-clash-protection", "", vars[var])
-        if not clang_has_option("-fstack-protector-strong"):
-            vars[var] = sub("-fstack-protector-strong", "", vars[var])
-        if not clang_has_option("-fno-semantic-interposition"):
-            vars[var] = sub("-fno-semantic-interposition", "", vars[var])
-        if not clang_has_option("-ffat-lto-objects"):
-            vars[var] = sub("-ffat-lto-objects", "", vars[var])
-        if not clang_has_option("-ftree-loop-distribute-patterns"):
-            vars[var] = sub("-ftree-loop-distribute-patterns", "", vars[var])
-        if not clang_has_option("-gno-variable-location-views"):
-            vars[var] = sub("-gno-variable-location-views", "", vars[var])
+        if var not in config_vars:
+            continue
+
+        # Split into individual flags to avoid regex boundary issues
+        flags = config_vars[var].split()
+
+        # Remove -specs=...
+        flags = [f for f in flags if not f.startswith("-specs=")]
+
+        options = (
+            "-mcet",
+            "-fcf-protection",
+            "-fstack-clash-protection",
+            "-fstack-protector-strong",
+            "-fno-semantic-interposition",
+            "-ffat-lto-objects",
+            "-ftree-loop-distribute-patterns",
+            "-gno-variable-location-views"
+        )
+        for option in options:
+            if not clang_has_option(cc, cc_args, src_feature_tests, option):
+                # Remove the option and any variant (e.g. -option=...)
+                flags = [f for f in flags if not f.startswith(option)]
+
+        # Re-join flags
+        config_vars[var] = " ".join(flags)
+
+
+class BuildExt(_build_ext):
+    """Custom build_ext command to set output directories."""
+
+    def __init__(self, *args, **kwargs):
+        self.build_lib = None
+        self.build_temp = None
+        super().__init__(*args, **kwargs)
+
+    def finalize_options(self) -> None:
+        _build_ext.finalize_options(self)
+        build_lib = os.getenv('PYTHON_EXTBUILD_LIB')
+        build_tmp = os.getenv('PYTHON_EXTBUILD_TMP')
+        if build_lib:
+            self.build_lib = build_lib
+        if build_tmp:
+            self.build_temp = build_tmp
 
-from setuptools import setup, Extension
 
-from setuptools.command.build_ext   import build_ext   as _build_ext
-from setuptools.command.install_lib import install_lib as _install_lib
+class InstallLib(_install_lib):
+    """Custom install_lib command to set output directory."""
 
-class build_ext(_build_ext):
-    def finalize_options(self):
-        _build_ext.finalize_options(self)
-        self.build_lib  = build_lib
-        self.build_temp = build_tmp
+    def __init__(self, *args, **kwargs):
+        self.build_dir = None
+        super().__init__(*args, **kwargs)
 
-class install_lib(_install_lib):
-    def finalize_options(self):
+    def finalize_options(self) -> None:
         _install_lib.finalize_options(self)
-        self.build_dir = build_lib
-
-
-cflags = getenv('CFLAGS', '').split()
-# switch off several checks (need to be at the end of cflags list)
-cflags += ['-fno-strict-aliasing', '-Wno-write-strings', '-Wno-unused-parameter', '-Wno-redundant-decls' ]
-if cc_is_clang:
-    cflags += ["-Wno-unused-command-line-argument" ]
-    if clang_has_option("-Wno-cast-function-type-mismatch"):
-        cflags += ["-Wno-cast-function-type-mismatch" ]
-else:
-    cflags += ['-Wno-cast-function-type' ]
-
-# The python headers have mixed code with declarations (decls after asserts, for instance)
-cflags += [ "-Wno-declaration-after-statement" ]
-
-src_perf  = f'{srctree}/tools/perf'
-build_lib = getenv('PYTHON_EXTBUILD_LIB')
-build_tmp = getenv('PYTHON_EXTBUILD_TMP')
-
-perf = Extension('perf',
-                 sources = [ src_perf + '/util/python.c' ],
-		         include_dirs = ['util/include'],
-		         extra_compile_args = cflags,
-                 )
-
-setup(name='perf',
-      version='0.1',
-      description='Interface with the Linux profiling infrastructure',
-      author='Arnaldo Carvalho de Melo',
-      author_email='acme@redhat.com',
-      license='GPLv2',
-      url='http://perf.wiki.kernel.org',
-      ext_modules=[perf],
-      cmdclass={'build_ext': build_ext, 'install_lib': install_lib})
+        build_lib = os.getenv('PYTHON_EXTBUILD_LIB')
+        if build_lib:
+            self.build_dir = build_lib
+
+
+def main() -> None:
+    """Main entry point for the setup script."""
+    cc_env = os.getenv("CC")
+    assert cc_env, "Environment variable CC not set"
+
+    # Safe parsing of CC environment variable which might contain options/quotes
+    cc_tokens = shlex.split(cc_env)
+    cc = cc_tokens[0]
+    cc_args = cc_tokens[1:]
+
+    # Run CC -v to check if it is clang.
+    try:
+        cc_info = subprocess.run(
+            [cc, "-v"], stderr=subprocess.PIPE, stdout=subprocess.DEVNULL, check=False
+        )
+        cc_is_clang = b"clang version" in cc_info.stderr
+    except OSError as e:
+        raise RuntimeError(f"Failed to execute compiler '{cc}': {e}") from e
+
+    srctree = os.getenv('srctree')
+    assert srctree, "Environment variable srctree, for the Linux sources, not set"
+    src_feature_tests = f'{srctree}/tools/build/feature'
+
+    if cc_is_clang:
+        filter_clang_options(cc, cc_args, src_feature_tests)
+
+    cflags = os.getenv('CFLAGS', '').split()
+    # switch off several checks (need to be at the end of cflags list)
+    cflags += [
+        '-fno-strict-aliasing',
+        '-Wno-write-strings',
+        '-Wno-unused-parameter',
+        '-Wno-redundant-decls'
+    ]
+    if cc_is_clang:
+        cflags += ["-Wno-unused-command-line-argument"]
+        if clang_has_option(
+            cc, cc_args, src_feature_tests, "-Wno-cast-function-type-mismatch"
+        ):
+            cflags += ["-Wno-cast-function-type-mismatch"]
+    else:
+        cflags += ['-Wno-cast-function-type']
+
+    # The python headers have mixed code with declarations (decls after asserts, for instance)
+    cflags += ["-Wno-declaration-after-statement"]
+
+    src_perf = f'{srctree}/tools/perf'
+
+    perf = Extension(
+        'perf',
+        sources=[os.path.join(src_perf, 'util/python.c')],
+        include_dirs=['util/include'],
+        extra_compile_args=cflags,
+    )
+
+    setup(
+        name='perf',
+        version='0.1',
+        description='Interface with the Linux profiling infrastructure',
+        author='Arnaldo Carvalho de Melo',
+        author_email='acme@redhat.com',
+        license='GPLv2',
+        url='http://perf.wiki.kernel.org',
+        ext_modules=[perf],
+        cmdclass={'build_ext': BuildExt, 'install_lib': InstallLib},
+    )
+
+
+if __name__ == '__main__':
+    main()
-- 
2.54.0.794.g4f17f83d09-goog

Re: [PATCH v1] perf python: Clean up and restructure setup.py

[Ian Rogers]

On Thu, May 21, 2026 at 10:55 AM Ian Rogers <irogers@google.com> wrote:
>
> Clean up and restructure the python setup script to resolve pylint
> warnings, improve code quality, and increase robustness and
> readability, targeting Python 3.9+ (the Linux kernel build minimum
> Python version).
>
> Changes:
> - Restructure the script to use a `main()` function as the entry point,
>   leaving only imports, classes, and pure functions at module level.
> - Eliminate all global/module-level variables, making them local to
>   `main()` or the respective classes/functions.
> - Make `clang_has_option` a pure function by passing all necessary
>   parameters explicitly.
> - Extract clang compiler flag filtering into a new
>   `filter_clang_options` helper function. This function uses a loop
>   over a tuple of options, replacing ~30 lines of repetitive blocks
>   and reducing branch/statement complexity in the main flow.
> - Cleanly define attributes in `__init__` for `BuildExt` and `InstallLib`
>   and read environment variables dynamically within the methods, removing
>   their dependency on global variables.
> - Replace legacy Popen with subprocess.run for safer process handling.
> - Use list-based flag filtering (split, filter, re-join) instead of regex
>   `re.sub` substitutions on space-separated compiler flag strings. This
>   avoids boundary bugs and safely handles flags with arguments (e.g.
>   `-fcf-protection=full`).
> - Safely parse `CC` env var using `shlex.split` to handle quotes and pass
>   compiler arguments as `list[str]` lists to helper functions, avoiding
>   redundant string formatting and parsing.
> - Remove unused `import re`.
> - Rename setuptools command subclasses to PascalCase (BuildExt, InstallLib).
> - Add type annotations to functions and methods.
> - Add missing docstrings for module, functions, and classes.
> - Split long lines to adhere to standard limits.
>
> Assisted-by: Antigravity:gemini-3.5-flash
> Signed-off-by: Ian Rogers <irogers@google.com>

Ping.

Thanks,
Ian

> ---
>  tools/perf/util/setup.py | 253 +++++++++++++++++++++++++--------------
>  1 file changed, 166 insertions(+), 87 deletions(-)
>
> diff --git a/tools/perf/util/setup.py b/tools/perf/util/setup.py
> index b65b1792ca05..55ff7d8cba7e 100644
> --- a/tools/perf/util/setup.py
> +++ b/tools/perf/util/setup.py
> @@ -1,108 +1,187 @@
> -from os import getenv, path
> -from subprocess import Popen, PIPE
> -from re import sub
> +"""Setup script for perf python extension.
> +
> +This script is used to build and install the perf python binding.
> +It handles compiler-specific flags, especially for clang, and configures
> +the setuptools Extension.
> +"""
> +
> +import os
>  import shlex
> +import subprocess
> +import sysconfig
>
> -cc = getenv("CC")
> -assert cc, "Environment variable CC not set"
> +from setuptools import setup, Extension
> +from setuptools.command.build_ext import build_ext as _build_ext
> +from setuptools.command.install_lib import install_lib as _install_lib
>
> -# Check if CC has options, as is the case in yocto, where it uses CC="cc --sysroot..."
> -cc_tokens = cc.split()
> -if len(cc_tokens) > 1:
> -    cc = cc_tokens[0]
> -    cc_options = " ".join([str(e) for e in cc_tokens[1:]]) + " "
> -else:
> -    cc_options = ""
>
> -# ignore optional stderr could be None as it is set to PIPE to avoid that.
> -# mypy: disable-error-code="union-attr"
> -cc_is_clang = b"clang version" in Popen([cc, "-v"], stderr=PIPE).stderr.readline()
> +def clang_has_option(cc: str, cc_args: list[str], src_feature_tests: str, option: str) -> bool:
> +    """Check if clang supports a specific option.
>
> -srctree = getenv('srctree')
> -assert srctree, "Environment variable srctree, for the Linux sources, not set"
> -src_feature_tests  = f'{srctree}/tools/build/feature'
> +    Args:
> +        cc: The compiler executable.
> +        cc_args: Compiler arguments from CC environment variable.
> +        src_feature_tests: Path to the feature tests directory.
> +        option: The compiler option to check (e.g., "-mcet").
>
> -def clang_has_option(option):
> +    Returns:
> +        True if the option is supported, False otherwise.
> +    """
>      error_substrings = (
>          b"unknown argument",
>          b"is not supported",
>          b"unknown warning option"
>      )
> -    cmd = shlex.split(f"{cc} {cc_options} {option}") + [
> +    cmd = [cc] + cc_args + [
> +        option,
>          "-o", "/dev/null",
> -        path.join(src_feature_tests, "test-hello.c")
> +        os.path.join(src_feature_tests, "test-hello.c")
>      ]
> -    cc_output = Popen(cmd, stderr=PIPE).stderr.readlines()
> +    try:
> +        res = subprocess.run(cmd, stderr=subprocess.PIPE, stdout=subprocess.DEVNULL, check=False)
> +        cc_output = res.stderr.splitlines()
> +    except OSError:
> +        return False
>      return not any(any(error in line for error in error_substrings) for line in cc_output)
>
> -if cc_is_clang:
> -    from sysconfig import get_config_vars
> -    vars = get_config_vars()
> +
> +def filter_clang_options(cc: str, cc_args: list[str], src_feature_tests: str) -> None:
> +    """Filter out unsupported clang options from sysconfig CFLAGS and OPT.
> +
> +    Args:
> +        cc: The compiler executable.
> +        cc_args: Compiler arguments from CC environment variable.
> +        src_feature_tests: Path to the feature tests directory.
> +    """
> +    config_vars = sysconfig.get_config_vars()
>      for var in ('CFLAGS', 'OPT'):
> -        vars[var] = sub("-specs=[^ ]+", "", vars[var])
> -        if not clang_has_option("-mcet"):
> -            vars[var] = sub("-mcet", "", vars[var])
> -        if not clang_has_option("-fcf-protection"):
> -            vars[var] = sub("-fcf-protection", "", vars[var])
> -        if not clang_has_option("-fstack-clash-protection"):
> -            vars[var] = sub("-fstack-clash-protection", "", vars[var])
> -        if not clang_has_option("-fstack-protector-strong"):
> -            vars[var] = sub("-fstack-protector-strong", "", vars[var])
> -        if not clang_has_option("-fno-semantic-interposition"):
> -            vars[var] = sub("-fno-semantic-interposition", "", vars[var])
> -        if not clang_has_option("-ffat-lto-objects"):
> -            vars[var] = sub("-ffat-lto-objects", "", vars[var])
> -        if not clang_has_option("-ftree-loop-distribute-patterns"):
> -            vars[var] = sub("-ftree-loop-distribute-patterns", "", vars[var])
> -        if not clang_has_option("-gno-variable-location-views"):
> -            vars[var] = sub("-gno-variable-location-views", "", vars[var])
> +        if var not in config_vars:
> +            continue
> +
> +        # Split into individual flags to avoid regex boundary issues
> +        flags = config_vars[var].split()
> +
> +        # Remove -specs=...
> +        flags = [f for f in flags if not f.startswith("-specs=")]
> +
> +        options = (
> +            "-mcet",
> +            "-fcf-protection",
> +            "-fstack-clash-protection",
> +            "-fstack-protector-strong",
> +            "-fno-semantic-interposition",
> +            "-ffat-lto-objects",
> +            "-ftree-loop-distribute-patterns",
> +            "-gno-variable-location-views"
> +        )
> +        for option in options:
> +            if not clang_has_option(cc, cc_args, src_feature_tests, option):
> +                # Remove the option and any variant (e.g. -option=...)
> +                flags = [f for f in flags if not f.startswith(option)]
> +
> +        # Re-join flags
> +        config_vars[var] = " ".join(flags)
> +
> +
> +class BuildExt(_build_ext):
> +    """Custom build_ext command to set output directories."""
> +
> +    def __init__(self, *args, **kwargs):
> +        self.build_lib = None
> +        self.build_temp = None
> +        super().__init__(*args, **kwargs)
> +
> +    def finalize_options(self) -> None:
> +        _build_ext.finalize_options(self)
> +        build_lib = os.getenv('PYTHON_EXTBUILD_LIB')
> +        build_tmp = os.getenv('PYTHON_EXTBUILD_TMP')
> +        if build_lib:
> +            self.build_lib = build_lib
> +        if build_tmp:
> +            self.build_temp = build_tmp
>
> -from setuptools import setup, Extension
>
> -from setuptools.command.build_ext   import build_ext   as _build_ext
> -from setuptools.command.install_lib import install_lib as _install_lib
> +class InstallLib(_install_lib):
> +    """Custom install_lib command to set output directory."""
>
> -class build_ext(_build_ext):
> -    def finalize_options(self):
> -        _build_ext.finalize_options(self)
> -        self.build_lib  = build_lib
> -        self.build_temp = build_tmp
> +    def __init__(self, *args, **kwargs):
> +        self.build_dir = None
> +        super().__init__(*args, **kwargs)
>
> -class install_lib(_install_lib):
> -    def finalize_options(self):
> +    def finalize_options(self) -> None:
>          _install_lib.finalize_options(self)
> -        self.build_dir = build_lib
> -
> -
> -cflags = getenv('CFLAGS', '').split()
> -# switch off several checks (need to be at the end of cflags list)
> -cflags += ['-fno-strict-aliasing', '-Wno-write-strings', '-Wno-unused-parameter', '-Wno-redundant-decls' ]
> -if cc_is_clang:
> -    cflags += ["-Wno-unused-command-line-argument" ]
> -    if clang_has_option("-Wno-cast-function-type-mismatch"):
> -        cflags += ["-Wno-cast-function-type-mismatch" ]
> -else:
> -    cflags += ['-Wno-cast-function-type' ]
> -
> -# The python headers have mixed code with declarations (decls after asserts, for instance)
> -cflags += [ "-Wno-declaration-after-statement" ]
> -
> -src_perf  = f'{srctree}/tools/perf'
> -build_lib = getenv('PYTHON_EXTBUILD_LIB')
> -build_tmp = getenv('PYTHON_EXTBUILD_TMP')
> -
> -perf = Extension('perf',
> -                 sources = [ src_perf + '/util/python.c' ],
> -                        include_dirs = ['util/include'],
> -                        extra_compile_args = cflags,
> -                 )
> -
> -setup(name='perf',
> -      version='0.1',
> -      description='Interface with the Linux profiling infrastructure',
> -      author='Arnaldo Carvalho de Melo',
> -      author_email='acme@redhat.com',
> -      license='GPLv2',
> -      url='http://perf.wiki.kernel.org',
> -      ext_modules=[perf],
> -      cmdclass={'build_ext': build_ext, 'install_lib': install_lib})
> +        build_lib = os.getenv('PYTHON_EXTBUILD_LIB')
> +        if build_lib:
> +            self.build_dir = build_lib
> +
> +
> +def main() -> None:
> +    """Main entry point for the setup script."""
> +    cc_env = os.getenv("CC")
> +    assert cc_env, "Environment variable CC not set"
> +
> +    # Safe parsing of CC environment variable which might contain options/quotes
> +    cc_tokens = shlex.split(cc_env)
> +    cc = cc_tokens[0]
> +    cc_args = cc_tokens[1:]
> +
> +    # Run CC -v to check if it is clang.
> +    try:
> +        cc_info = subprocess.run(
> +            [cc, "-v"], stderr=subprocess.PIPE, stdout=subprocess.DEVNULL, check=False
> +        )
> +        cc_is_clang = b"clang version" in cc_info.stderr
> +    except OSError as e:
> +        raise RuntimeError(f"Failed to execute compiler '{cc}': {e}") from e
> +
> +    srctree = os.getenv('srctree')
> +    assert srctree, "Environment variable srctree, for the Linux sources, not set"
> +    src_feature_tests = f'{srctree}/tools/build/feature'
> +
> +    if cc_is_clang:
> +        filter_clang_options(cc, cc_args, src_feature_tests)
> +
> +    cflags = os.getenv('CFLAGS', '').split()
> +    # switch off several checks (need to be at the end of cflags list)
> +    cflags += [
> +        '-fno-strict-aliasing',
> +        '-Wno-write-strings',
> +        '-Wno-unused-parameter',
> +        '-Wno-redundant-decls'
> +    ]
> +    if cc_is_clang:
> +        cflags += ["-Wno-unused-command-line-argument"]
> +        if clang_has_option(
> +            cc, cc_args, src_feature_tests, "-Wno-cast-function-type-mismatch"
> +        ):
> +            cflags += ["-Wno-cast-function-type-mismatch"]
> +    else:
> +        cflags += ['-Wno-cast-function-type']
> +
> +    # The python headers have mixed code with declarations (decls after asserts, for instance)
> +    cflags += ["-Wno-declaration-after-statement"]
> +
> +    src_perf = f'{srctree}/tools/perf'
> +
> +    perf = Extension(
> +        'perf',
> +        sources=[os.path.join(src_perf, 'util/python.c')],
> +        include_dirs=['util/include'],
> +        extra_compile_args=cflags,
> +    )
> +
> +    setup(
> +        name='perf',
> +        version='0.1',
> +        description='Interface with the Linux profiling infrastructure',
> +        author='Arnaldo Carvalho de Melo',
> +        author_email='acme@redhat.com',
> +        license='GPLv2',
> +        url='http://perf.wiki.kernel.org',
> +        ext_modules=[perf],
> +        cmdclass={'build_ext': BuildExt, 'install_lib': InstallLib},
> +    )
> +
> +
> +if __name__ == '__main__':
> +    main()
> --
> 2.54.0.794.g4f17f83d09-goog
>

Re: [PATCH v1] perf python: Clean up and restructure setup.py

[Namhyung Kim]

On Wed, Jul 22, 2026 at 09:51:34AM -0700, Ian Rogers wrote:
> On Thu, May 21, 2026 at 10:55 AM Ian Rogers <irogers@google.com> wrote:
> >
> > Clean up and restructure the python setup script to resolve pylint
> > warnings, improve code quality, and increase robustness and
> > readability, targeting Python 3.9+ (the Linux kernel build minimum
> > Python version).
> >
> > Changes:
> > - Restructure the script to use a `main()` function as the entry point,
> >   leaving only imports, classes, and pure functions at module level.
> > - Eliminate all global/module-level variables, making them local to
> >   `main()` or the respective classes/functions.
> > - Make `clang_has_option` a pure function by passing all necessary
> >   parameters explicitly.
> > - Extract clang compiler flag filtering into a new
> >   `filter_clang_options` helper function. This function uses a loop
> >   over a tuple of options, replacing ~30 lines of repetitive blocks
> >   and reducing branch/statement complexity in the main flow.
> > - Cleanly define attributes in `__init__` for `BuildExt` and `InstallLib`
> >   and read environment variables dynamically within the methods, removing
> >   their dependency on global variables.
> > - Replace legacy Popen with subprocess.run for safer process handling.
> > - Use list-based flag filtering (split, filter, re-join) instead of regex
> >   `re.sub` substitutions on space-separated compiler flag strings. This
> >   avoids boundary bugs and safely handles flags with arguments (e.g.
> >   `-fcf-protection=full`).
> > - Safely parse `CC` env var using `shlex.split` to handle quotes and pass
> >   compiler arguments as `list[str]` lists to helper functions, avoiding
> >   redundant string formatting and parsing.
> > - Remove unused `import re`.
> > - Rename setuptools command subclasses to PascalCase (BuildExt, InstallLib).
> > - Add type annotations to functions and methods.
> > - Add missing docstrings for module, functions, and classes.
> > - Split long lines to adhere to standard limits.
> >
> > Assisted-by: Antigravity:gemini-3.5-flash
> > Signed-off-by: Ian Rogers <irogers@google.com>
> 
> Ping.

Sorry for the delay.  Can you please resend the series?

Thanks,
Namhyung

[PATCH v2] perf python: Clean up and restructure setup.py

[Ian Rogers]

Clean up and restructure the python setup script to resolve pylint
warnings, improve code quality, and increase robustness and
readability, targeting Python 3.9+ (the Linux kernel build minimum
Python version).

Changes:
- Restructure the script to use a `main()` function as the entry point,
  leaving only imports, classes, and pure functions at module level.
- Eliminate all global/module-level variables, making them local to
  `main()` or the respective classes/functions.
- Make `clang_has_option` a pure function by passing all necessary
  parameters explicitly.
- Extract clang compiler flag filtering into a new
  `filter_clang_options` helper function. This function uses a loop
  over a tuple of options, replacing ~30 lines of repetitive blocks
  and reducing branch/statement complexity in the main flow.
- Cleanly define attributes in `__init__` for `BuildExt` and `InstallLib`
  and read environment variables dynamically within the methods, removing
  their dependency on global variables.
- Replace legacy Popen with subprocess.run for safer process handling.
- Use list-based flag filtering (split, filter, re-join) instead of regex
  `re.sub` substitutions on space-separated compiler flag strings. This
  avoids boundary bugs and safely handles flags with arguments (e.g.
  `-fcf-protection=full`).
- Safely parse `CC` env var using `shlex.split` to handle quotes and pass
  compiler arguments as `list[str]` lists to helper functions, avoiding
  redundant string formatting and parsing.
- Remove unused `import re`.
- Rename setuptools command subclasses to PascalCase (BuildExt, InstallLib).
- Add type annotations to functions and methods.
- Add missing docstrings for module, functions, and classes.
- Split long lines to adhere to standard limits.

Assisted-by: Antigravity:gemini-3.5-flash
Signed-off-by: Ian Rogers <irogers@google.com>
---
v2: Rebase
---
 tools/perf/util/setup.py | 248 ++++++++++++++++++++++++++-------------
 1 file changed, 164 insertions(+), 84 deletions(-)

diff --git a/tools/perf/util/setup.py b/tools/perf/util/setup.py
index cb14554454a2..1385f07424b7 100644
--- a/tools/perf/util/setup.py
+++ b/tools/perf/util/setup.py
@@ -1,112 +1,192 @@
-from os import getenv, path
-from subprocess import Popen, PIPE
-from re import sub
+"""Setup script for perf python extension.
+
+This script is used to build and install the perf python binding.
+It handles compiler-specific flags, especially for clang, and configures
+the setuptools Extension.
+"""
+
+import os
 import shlex
 import shutil
+import subprocess
+import sysconfig
 
-cc = getenv("CC")
-assert cc, "Environment variable CC not set"
+from setuptools import setup, Extension
+from setuptools.command.build_ext import build_ext as _build_ext
+from setuptools.command.install_lib import install_lib as _install_lib
 
-# Check if CC has options, as is the case in yocto, where it uses CC="cc --sysroot..."
-cc_tokens = cc.split()
-if len(cc_tokens) > 1:
-    cc = cc_tokens[0]
-    cc_options = " ".join([str(e) for e in cc_tokens[1:]]) + " "
-else:
-    cc_options = ""
 
-# ignore optional stderr could be None as it is set to PIPE to avoid that.
-# mypy: disable-error-code="union-attr"
-cc_is_clang = b"clang version" in Popen([cc, "-v"], stderr=PIPE).stderr.readline()
+def clang_has_option(cc: str, cc_args: list[str], src_feature_tests: str, option: str) -> bool:
+    """Check if clang supports a specific option.
 
-srctree = getenv('srctree')
-assert srctree, "Environment variable srctree, for the Linux sources, not set"
-src_feature_tests  = f'{srctree}/tools/build/feature'
+    Args:
+        cc: The compiler executable.
+        cc_args: Compiler arguments from CC environment variable.
+        src_feature_tests: Path to the feature tests directory.
+        option: The compiler option to check (e.g., "-mcet").
 
-def clang_has_option(option):
+    Returns:
+        True if the option is supported, False otherwise.
+    """
     error_substrings = (
         b"unknown argument",
         b"is not supported",
         b"unknown warning option"
     )
-    cmd = shlex.split(f"{cc} {cc_options} {option}") + [
+    cmd = [cc] + cc_args + [
+        option,
         "-o", "/dev/null",
-        path.join(src_feature_tests, "test-hello.c")
+        os.path.join(src_feature_tests, "test-hello.c")
     ]
-    cc_output = Popen(cmd, stderr=PIPE).stderr.readlines()
+    try:
+        res = subprocess.run(cmd, stderr=subprocess.PIPE, stdout=subprocess.DEVNULL, check=False)
+        cc_output = res.stderr.splitlines()
+    except OSError:
+        return False
     return not any(any(error in line for error in error_substrings) for line in cc_output)
 
-if cc_is_clang:
-    from sysconfig import get_config_vars
-    vars = get_config_vars()
+
+def filter_clang_options(cc: str, cc_args: list[str], src_feature_tests: str) -> None:
+    """Filter out unsupported clang options from sysconfig CFLAGS and OPT.
+
+    Args:
+        cc: The compiler executable.
+        cc_args: Compiler arguments from CC environment variable.
+        src_feature_tests: Path to the feature tests directory.
+    """
+    config_vars = sysconfig.get_config_vars()
     for var in ('CFLAGS', 'OPT'):
-        vars[var] = sub("-specs=[^ ]+", "", vars[var])
-        if not clang_has_option("-mcet"):
-            vars[var] = sub("-mcet", "", vars[var])
-        if not clang_has_option("-fcf-protection"):
-            vars[var] = sub("-fcf-protection", "", vars[var])
-        if not clang_has_option("-fstack-clash-protection"):
-            vars[var] = sub("-fstack-clash-protection", "", vars[var])
-        if not clang_has_option("-fstack-protector-strong"):
-            vars[var] = sub("-fstack-protector-strong", "", vars[var])
-        if not clang_has_option("-fno-semantic-interposition"):
-            vars[var] = sub("-fno-semantic-interposition", "", vars[var])
-        if not clang_has_option("-ffat-lto-objects"):
-            vars[var] = sub("-ffat-lto-objects", "", vars[var])
-        if not clang_has_option("-ftree-loop-distribute-patterns"):
-            vars[var] = sub("-ftree-loop-distribute-patterns", "", vars[var])
-        if not clang_has_option("-gno-variable-location-views"):
-            vars[var] = sub("-gno-variable-location-views", "", vars[var])
+        if var not in config_vars:
+            continue
+
+        # Split into individual flags to avoid regex boundary issues
+        flags = config_vars[var].split()
+
+        # Remove -specs=...
+        flags = [f for f in flags if not f.startswith("-specs=")]
+
+        options = (
+            "-mcet",
+            "-fcf-protection",
+            "-fstack-clash-protection",
+            "-fstack-protector-strong",
+            "-fno-semantic-interposition",
+            "-ffat-lto-objects",
+            "-ftree-loop-distribute-patterns",
+            "-gno-variable-location-views"
+        )
+        for option in options:
+            if not clang_has_option(cc, cc_args, src_feature_tests, option):
+                # Remove the option and any variant (e.g. -option=...)
+                flags = [f for f in flags if not f.startswith(option)]
+
+        # Re-join flags
+        config_vars[var] = " ".join(flags)
+
+
+class BuildExt(_build_ext):
+    """Custom build_ext command to set output directories."""
+
+    def __init__(self, *args, **kwargs):
+        self.build_lib = None
+        self.build_temp = None
+        super().__init__(*args, **kwargs)
+
+    def finalize_options(self) -> None:
+        _build_ext.finalize_options(self)
+        build_lib = os.getenv('PYTHON_EXTBUILD_LIB')
+        build_tmp = os.getenv('PYTHON_EXTBUILD_TMP')
+        if build_lib:
+            self.build_lib = build_lib
+        if build_tmp:
+            self.build_temp = build_tmp
 
-from setuptools import setup, Extension
 
-from setuptools.command.build_ext   import build_ext   as _build_ext
-from setuptools.command.install_lib import install_lib as _install_lib
+class InstallLib(_install_lib):
+    """Custom install_lib command to set output directory."""
 
-class build_ext(_build_ext):
-    def finalize_options(self):
-        _build_ext.finalize_options(self)
-        self.build_lib  = build_lib
-        self.build_temp = build_tmp
+    def __init__(self, *args, **kwargs):
+        self.build_dir = None
+        super().__init__(*args, **kwargs)
 
-class install_lib(_install_lib):
-    def finalize_options(self):
+    def finalize_options(self) -> None:
         _install_lib.finalize_options(self)
-        self.build_dir = build_lib
+        build_lib = os.getenv('PYTHON_EXTBUILD_LIB')
+        if build_lib:
+            self.build_dir = build_lib
 
     def run(self):
         _install_lib.run(self)
         shutil.copy2(f'{src_perf}/python/perf.pyi', self.install_dir)
 
 
-# switch off several checks (need to be at the end of cflags list)
-extra_cflags = ['-fno-strict-aliasing', '-Wno-write-strings', '-Wno-unused-parameter', '-Wno-redundant-decls' ]
-if cc_is_clang:
-    extra_cflags += ["-Wno-unused-command-line-argument" ]
-    if clang_has_option("-Wno-cast-function-type-mismatch"):
-        extra_cflags += ["-Wno-cast-function-type-mismatch" ]
-else:
-    extra_cflags += ['-Wno-cast-function-type' ]
-
-# The python headers have mixed code with declarations (decls after asserts, for instance)
-extra_cflags += [ "-Wno-declaration-after-statement" ]
-
-src_perf  = f'{srctree}/tools/perf'
-build_lib = getenv('PYTHON_EXTBUILD_LIB')
-build_tmp = getenv('PYTHON_EXTBUILD_TMP')
-
-perf = Extension('perf',
-                 sources = [ src_perf + '/util/python.c' ],
-		         include_dirs = ['util/include'],
-		         extra_compile_args = extra_cflags,
-                 )
-
-setup(name='perf',
-      version='0.1',
-      description='Interface with the Linux profiling infrastructure',
-      author='Arnaldo Carvalho de Melo',
-      author_email='acme@redhat.com',
-      license='GPLv2',
-      url='http://perf.wiki.kernel.org',
-      ext_modules=[perf],
-      cmdclass={'build_ext': build_ext, 'install_lib': install_lib})
+def main() -> None:
+    """Main entry point for the setup script."""
+    cc_env = os.getenv("CC")
+    assert cc_env, "Environment variable CC not set"
+
+    # Safe parsing of CC environment variable which might contain options/quotes
+    cc_tokens = shlex.split(cc_env)
+    cc = cc_tokens[0]
+    cc_args = cc_tokens[1:]
+
+    # Run CC -v to check if it is clang.
+    try:
+        cc_info = subprocess.run(
+            [cc, "-v"], stderr=subprocess.PIPE, stdout=subprocess.DEVNULL, check=False
+        )
+        cc_is_clang = b"clang version" in cc_info.stderr
+    except OSError as e:
+        raise RuntimeError(f"Failed to execute compiler '{cc}': {e}") from e
+
+    srctree = os.getenv('srctree')
+    assert srctree, "Environment variable srctree, for the Linux sources, not set"
+    src_feature_tests = f'{srctree}/tools/build/feature'
+
+    if cc_is_clang:
+        filter_clang_options(cc, cc_args, src_feature_tests)
+
+    cflags = os.getenv('CFLAGS', '').split()
+    # switch off several checks (need to be at the end of cflags list)
+    cflags += [
+        '-fno-strict-aliasing',
+        '-Wno-write-strings',
+        '-Wno-unused-parameter',
+        '-Wno-redundant-decls'
+    ]
+    if cc_is_clang:
+        cflags += ["-Wno-unused-command-line-argument"]
+        if clang_has_option(
+            cc, cc_args, src_feature_tests, "-Wno-cast-function-type-mismatch"
+        ):
+            cflags += ["-Wno-cast-function-type-mismatch"]
+    else:
+        cflags += ['-Wno-cast-function-type']
+
+    # The python headers have mixed code with declarations (decls after asserts, for instance)
+    cflags += ["-Wno-declaration-after-statement"]
+
+    src_perf = f'{srctree}/tools/perf'
+
+    perf = Extension(
+        'perf',
+        sources=[os.path.join(src_perf, 'util/python.c')],
+        include_dirs=['util/include'],
+        extra_compile_args=cflags,
+    )
+
+    setup(
+        name='perf',
+        version='0.1',
+        description='Interface with the Linux profiling infrastructure',
+        author='Arnaldo Carvalho de Melo',
+        author_email='acme@redhat.com',
+        license='GPLv2',
+        url='http://perf.wiki.kernel.org',
+        ext_modules=[perf],
+        cmdclass={'build_ext': BuildExt, 'install_lib': InstallLib},
+    )
+
+
+if __name__ == '__main__':
+    main()
-- 
2.55.0.229.g6434b31f56-goog

Re: [PATCH v2] perf python: Clean up and restructure setup.py

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Low] Unresolved reference to `src_perf` in `InstallLib.run()` will raise a `NameError` during the installation phase.
- [Low] Naive splitting of compiler flags (`CFLAGS` and `OPT`) using `.split()` breaks quoted arguments and redundantly duplicates user flags.
--

--- Patch [1]: [PATCH v2] perf python: Clean up and restructure setup.py ---
commit 48e3810550a434c966bd3941fa49269f6b80e25e
Author: Ian Rogers <irogers@google.com>

perf python: Clean up and restructure setup.py

This commit cleans up and restructures the python setup script to resolve
pylint warnings and improve code quality. It moves global logic into a
main() function and extracts compiler flag filtering into a helper.

> diff --git a/tools/perf/util/setup.py b/tools/perf/util/setup.py
> index cb14554454a21..1385f07424b7c 100644
> --- a/tools/perf/util/setup.py
> +++ b/tools/perf/util/setup.py
[ ... ]
> +def filter_clang_options(cc: str, cc_args: list[str], src_feature_tests: str) -> None:
> +    """Filter out unsupported clang options from sysconfig CFLAGS and OPT.
> +
> +    Args:
> +        cc: The compiler executable.
> +        cc_args: Compiler arguments from CC environment variable.
> +        src_feature_tests: Path to the feature tests directory.
> +    """
> +    config_vars = sysconfig.get_config_vars()
>      for var in ('CFLAGS', 'OPT'):
> -        vars[var] = sub("-specs=[^ ]+", "", vars[var])
> +        if var not in config_vars:
> +            continue
> +
> +        # Split into individual flags to avoid regex boundary issues
> +        flags = config_vars[var].split()

[Severity: Low]
Does using a simple string split here break quoted compiler flags?

If the system Python configuration provides CFLAGS or OPT with quoted
arguments (e.g., -D"MACRO='some string'"), it appears this will destructively
split them on spaces into invalid fragments.

Should this use a quote-aware parser like shlex.split() instead?

[ ... ]
> +class InstallLib(_install_lib):
> +    """Custom install_lib command to set output directory."""
>  
> -class install_lib(_install_lib):
> -    def finalize_options(self):
> +    def __init__(self, *args, **kwargs):
> +        self.build_dir = None
> +        super().__init__(*args, **kwargs)
> +
> +    def finalize_options(self) -> None:
>          _install_lib.finalize_options(self)
> -        self.build_dir = build_lib
> +        build_lib = os.getenv('PYTHON_EXTBUILD_LIB')
> +        if build_lib:
> +            self.build_dir = build_lib
>  
>      def run(self):
>          _install_lib.run(self)
>          shutil.copy2(f'{src_perf}/python/perf.pyi', self.install_dir)

[Severity: Low]
Will this raise a NameError exception during installation?

The src_perf variable was refactored out of the module scope and moved into
the main() local scope, making it undefined here in InstallLib.run().

[ ... ]
> +def main() -> None:
[ ... ]
> +    if cc_is_clang:
> +        filter_clang_options(cc, cc_args, src_feature_tests)
> +
> +    cflags = os.getenv('CFLAGS', '').split()

[Severity: Low]
Similarly to the sysconfig variables, does this naive split break quoted
arguments in the CFLAGS environment variable?

Also, since setuptools inherently parses and applies CFLAGS from the
environment during extension compilation, will manually appending this to
extra_compile_args duplicate the user flags?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260723164421.1232688-1-irogers@google.com?part=1

[PATCH v3] perf python: Clean up and restructure setup.py

[Ian Rogers]

Clean up and restructure the python setup script to resolve pylint
warnings, improve code quality, and increase robustness and
readability, targeting Python 3.9+ (the Linux kernel build minimum
Python version).

Changes:
- Restructure the script to use a `main()` function as the entry point,
  leaving only imports, classes, and pure functions at module level.
- Eliminate all global/module-level variables, making them local to
  `main()` or the respective classes/functions.
- Make `clang_has_option` a pure function by passing all necessary
  parameters explicitly.
- Extract clang compiler flag filtering into a new
  `filter_clang_options` helper function. This function uses a loop
  over a tuple of options, replacing ~30 lines of repetitive blocks
  and reducing branch/statement complexity in the main flow.
- Cleanly define attributes in `__init__` for `BuildExt` and
  `InstallLib` and read environment variables dynamically within the
  methods (including `srctree` in `InstallLib.run`), removing their
  dependency on global variables.
- Replace legacy Popen with subprocess.run for safer process handling.
- Use quote-aware flag filtering (`shlex.split`, filter, `shlex.join`)
  on sysconfig CFLAGS and OPT instead of regex `re.sub` substitutions.
  This avoids boundary bugs and safely handles quoted arguments and
  options with values.
- Rely on setuptools to handle user CFLAGS from the environment
  directly rather than manually prepending them to extra_compile_args.
- Safely parse `CC` env var using `shlex.split` to handle quotes and
  pass compiler arguments as `list[str]` lists to helper functions,
  avoiding redundant string formatting and parsing.
- Remove unused `import re`.
- Rename setuptools command subclasses to PascalCase (BuildExt,
  InstallLib).
- Add type annotations to functions and methods.
- Add missing docstrings for module, functions, and classes.
- Split long lines to adhere to standard limits.

Assisted-by: Antigravity:gemini-3.5-flash
Signed-off-by: Ian Rogers <irogers@google.com>
---
v3:
  - Address Sashiko review feedback:
    - Use shlex.split() and shlex.join() in filter_clang_options()
      to handle quoted arguments.
    - Resolve NameError for src_perf in InstallLib.run() by resolving
      srctree/src_perf dynamically.
    - Remove manual CFLAGS splitting and duplication in main(), letting
      setuptools apply environment CFLAGS.
  - Add SPDX-License-Identifier header tag.
v2: Rebase
---
 tools/perf/util/setup.py | 256 ++++++++++++++++++++++++++-------------
 1 file changed, 169 insertions(+), 87 deletions(-)

diff --git a/tools/perf/util/setup.py b/tools/perf/util/setup.py
index cb14554454a2..8380980ade4c 100644
--- a/tools/perf/util/setup.py
+++ b/tools/perf/util/setup.py
@@ -1,112 +1,194 @@
-from os import getenv, path
-from subprocess import Popen, PIPE
-from re import sub
+# SPDX-License-Identifier: GPL-2.0
+"""Setup script for perf python extension.
+
+This script is used to build and install the perf python binding.
+It handles compiler-specific flags, especially for clang, and configures
+the setuptools Extension.
+"""
+
+import os
 import shlex
 import shutil
+import subprocess
+import sysconfig
 
-cc = getenv("CC")
-assert cc, "Environment variable CC not set"
+from setuptools import setup, Extension
+from setuptools.command.build_ext import build_ext as _build_ext
+from setuptools.command.install_lib import install_lib as _install_lib
 
-# Check if CC has options, as is the case in yocto, where it uses CC="cc --sysroot..."
-cc_tokens = cc.split()
-if len(cc_tokens) > 1:
-    cc = cc_tokens[0]
-    cc_options = " ".join([str(e) for e in cc_tokens[1:]]) + " "
-else:
-    cc_options = ""
 
-# ignore optional stderr could be None as it is set to PIPE to avoid that.
-# mypy: disable-error-code="union-attr"
-cc_is_clang = b"clang version" in Popen([cc, "-v"], stderr=PIPE).stderr.readline()
+def clang_has_option(cc: str, cc_args: list[str], src_feature_tests: str, option: str) -> bool:
+    """Check if clang supports a specific option.
 
-srctree = getenv('srctree')
-assert srctree, "Environment variable srctree, for the Linux sources, not set"
-src_feature_tests  = f'{srctree}/tools/build/feature'
+    Args:
+        cc: The compiler executable.
+        cc_args: Compiler arguments from CC environment variable.
+        src_feature_tests: Path to the feature tests directory.
+        option: The compiler option to check (e.g., "-mcet").
 
-def clang_has_option(option):
+    Returns:
+        True if the option is supported, False otherwise.
+    """
     error_substrings = (
         b"unknown argument",
         b"is not supported",
         b"unknown warning option"
     )
-    cmd = shlex.split(f"{cc} {cc_options} {option}") + [
+    cmd = [cc] + cc_args + [
+        option,
         "-o", "/dev/null",
-        path.join(src_feature_tests, "test-hello.c")
+        os.path.join(src_feature_tests, "test-hello.c")
     ]
-    cc_output = Popen(cmd, stderr=PIPE).stderr.readlines()
+    try:
+        res = subprocess.run(cmd, stderr=subprocess.PIPE, stdout=subprocess.DEVNULL, check=False)
+        cc_output = res.stderr.splitlines()
+    except OSError:
+        return False
     return not any(any(error in line for error in error_substrings) for line in cc_output)
 
-if cc_is_clang:
-    from sysconfig import get_config_vars
-    vars = get_config_vars()
+
+def filter_clang_options(cc: str, cc_args: list[str], src_feature_tests: str) -> None:
+    """Filter out unsupported clang options from sysconfig CFLAGS and OPT.
+
+    Args:
+        cc: The compiler executable.
+        cc_args: Compiler arguments from CC environment variable.
+        src_feature_tests: Path to the feature tests directory.
+    """
+    config_vars = sysconfig.get_config_vars()
     for var in ('CFLAGS', 'OPT'):
-        vars[var] = sub("-specs=[^ ]+", "", vars[var])
-        if not clang_has_option("-mcet"):
-            vars[var] = sub("-mcet", "", vars[var])
-        if not clang_has_option("-fcf-protection"):
-            vars[var] = sub("-fcf-protection", "", vars[var])
-        if not clang_has_option("-fstack-clash-protection"):
-            vars[var] = sub("-fstack-clash-protection", "", vars[var])
-        if not clang_has_option("-fstack-protector-strong"):
-            vars[var] = sub("-fstack-protector-strong", "", vars[var])
-        if not clang_has_option("-fno-semantic-interposition"):
-            vars[var] = sub("-fno-semantic-interposition", "", vars[var])
-        if not clang_has_option("-ffat-lto-objects"):
-            vars[var] = sub("-ffat-lto-objects", "", vars[var])
-        if not clang_has_option("-ftree-loop-distribute-patterns"):
-            vars[var] = sub("-ftree-loop-distribute-patterns", "", vars[var])
-        if not clang_has_option("-gno-variable-location-views"):
-            vars[var] = sub("-gno-variable-location-views", "", vars[var])
+        if var not in config_vars:
+            continue
+
+        # Split into individual flags using shlex to preserve quoted arguments
+        flags = shlex.split(config_vars[var])
+
+        # Remove -specs=...
+        flags = [f for f in flags if not f.startswith("-specs=")]
+
+        options = (
+            "-mcet",
+            "-fcf-protection",
+            "-fstack-clash-protection",
+            "-fstack-protector-strong",
+            "-fno-semantic-interposition",
+            "-ffat-lto-objects",
+            "-ftree-loop-distribute-patterns",
+            "-gno-variable-location-views"
+        )
+        for option in options:
+            if not clang_has_option(cc, cc_args, src_feature_tests, option):
+                # Remove the option and any variant (e.g. -option=...)
+                flags = [f for f in flags if not f.startswith(option)]
+
+        # Re-join flags preserving quoting
+        config_vars[var] = shlex.join(flags)
+
+
+class BuildExt(_build_ext):
+    """Custom build_ext command to set output directories."""
+
+    def __init__(self, *args, **kwargs):
+        self.build_lib = None
+        self.build_temp = None
+        super().__init__(*args, **kwargs)
+
+    def finalize_options(self) -> None:
+        _build_ext.finalize_options(self)
+        build_lib = os.getenv('PYTHON_EXTBUILD_LIB')
+        build_tmp = os.getenv('PYTHON_EXTBUILD_TMP')
+        if build_lib:
+            self.build_lib = build_lib
+        if build_tmp:
+            self.build_temp = build_tmp
 
-from setuptools import setup, Extension
 
-from setuptools.command.build_ext   import build_ext   as _build_ext
-from setuptools.command.install_lib import install_lib as _install_lib
+class InstallLib(_install_lib):
+    """Custom install_lib command to set output directory."""
 
-class build_ext(_build_ext):
-    def finalize_options(self):
-        _build_ext.finalize_options(self)
-        self.build_lib  = build_lib
-        self.build_temp = build_tmp
+    def __init__(self, *args, **kwargs):
+        self.build_dir = None
+        super().__init__(*args, **kwargs)
 
-class install_lib(_install_lib):
-    def finalize_options(self):
+    def finalize_options(self) -> None:
         _install_lib.finalize_options(self)
-        self.build_dir = build_lib
+        build_lib = os.getenv('PYTHON_EXTBUILD_LIB')
+        if build_lib:
+            self.build_dir = build_lib
 
     def run(self):
         _install_lib.run(self)
-        shutil.copy2(f'{src_perf}/python/perf.pyi', self.install_dir)
-
-
-# switch off several checks (need to be at the end of cflags list)
-extra_cflags = ['-fno-strict-aliasing', '-Wno-write-strings', '-Wno-unused-parameter', '-Wno-redundant-decls' ]
-if cc_is_clang:
-    extra_cflags += ["-Wno-unused-command-line-argument" ]
-    if clang_has_option("-Wno-cast-function-type-mismatch"):
-        extra_cflags += ["-Wno-cast-function-type-mismatch" ]
-else:
-    extra_cflags += ['-Wno-cast-function-type' ]
-
-# The python headers have mixed code with declarations (decls after asserts, for instance)
-extra_cflags += [ "-Wno-declaration-after-statement" ]
-
-src_perf  = f'{srctree}/tools/perf'
-build_lib = getenv('PYTHON_EXTBUILD_LIB')
-build_tmp = getenv('PYTHON_EXTBUILD_TMP')
-
-perf = Extension('perf',
-                 sources = [ src_perf + '/util/python.c' ],
-		         include_dirs = ['util/include'],
-		         extra_compile_args = extra_cflags,
-                 )
-
-setup(name='perf',
-      version='0.1',
-      description='Interface with the Linux profiling infrastructure',
-      author='Arnaldo Carvalho de Melo',
-      author_email='acme@redhat.com',
-      license='GPLv2',
-      url='http://perf.wiki.kernel.org',
-      ext_modules=[perf],
-      cmdclass={'build_ext': build_ext, 'install_lib': install_lib})
+        srctree = os.getenv('srctree', '.')
+        src_perf = os.path.join(srctree, 'tools/perf')
+        shutil.copy2(os.path.join(src_perf, 'python/perf.pyi'), self.install_dir)
+
+
+def main() -> None:
+    """Main entry point for the setup script."""
+    cc_env = os.getenv("CC")
+    assert cc_env, "Environment variable CC not set"
+
+    # Safe parsing of CC environment variable which might contain options/quotes
+    cc_tokens = shlex.split(cc_env)
+    cc = cc_tokens[0]
+    cc_args = cc_tokens[1:]
+
+    # Run CC -v to check if it is clang.
+    try:
+        cc_info = subprocess.run(
+            [cc, "-v"], stderr=subprocess.PIPE, stdout=subprocess.DEVNULL, check=False
+        )
+        cc_is_clang = b"clang version" in cc_info.stderr
+    except OSError as e:
+        raise RuntimeError(f"Failed to execute compiler '{cc}': {e}") from e
+
+    srctree = os.getenv('srctree')
+    assert srctree, "Environment variable srctree, for the Linux sources, not set"
+    src_feature_tests = f'{srctree}/tools/build/feature'
+
+    if cc_is_clang:
+        filter_clang_options(cc, cc_args, src_feature_tests)
+
+    # switch off several checks (need to be at the end of cflags list)
+    cflags = [
+        '-fno-strict-aliasing',
+        '-Wno-write-strings',
+        '-Wno-unused-parameter',
+        '-Wno-redundant-decls'
+    ]
+    if cc_is_clang:
+        cflags += ["-Wno-unused-command-line-argument"]
+        if clang_has_option(
+            cc, cc_args, src_feature_tests, "-Wno-cast-function-type-mismatch"
+        ):
+            cflags += ["-Wno-cast-function-type-mismatch"]
+    else:
+        cflags += ['-Wno-cast-function-type']
+
+    # The python headers have mixed code with declarations (decls after asserts, for instance)
+    cflags += ["-Wno-declaration-after-statement"]
+
+    src_perf = f'{srctree}/tools/perf'
+
+    perf = Extension(
+        'perf',
+        sources=[os.path.join(src_perf, 'util/python.c')],
+        include_dirs=['util/include'],
+        extra_compile_args=cflags,
+    )
+
+    setup(
+        name='perf',
+        version='0.1',
+        description='Interface with the Linux profiling infrastructure',
+        author='Arnaldo Carvalho de Melo',
+        author_email='acme@redhat.com',
+        license='GPLv2',
+        url='http://perf.wiki.kernel.org',
+        ext_modules=[perf],
+        cmdclass={'build_ext': BuildExt, 'install_lib': InstallLib},
+    )
+
+
+if __name__ == '__main__':
+    main()
-- 
2.55.0.229.g6434b31f56-goog