Date:	Mon, 29 Sep 2014 14:08:56 +0200
From:	Valentin Rothberg <valentinrothberg@...il.com>
To:	Paul Bolle <pebolle@...cali.nl>
Cc:	akpm@...ux-foundation.org,
	Stefan Hengelein <stefan.hengelein@....de>,
	linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7] checkkconfigsymbols.sh: reimplementation in python

On Mon, Sep 29, 2014 at 12:28 PM, Paul Bolle <pebolle@...cali.nl> wrote:
> [Added  linux-kbuild@...r.kernel.org.]
>
> On Sun, 2014-09-28 at 17:55 +0200, Valentin Rothberg wrote:
>> The scripts/checkkconfigsymbols.sh script searches Kconfig features
>> in the source code that are not defined in Kconfig. Such identifiers
>> always evaluate to false and are the source of various kinds of bugs.
>> However, the shell script is slow and it does not detect such broken
>> references in Kbuild and Kconfig files (e.g., ``depends on UNDEFINED´´).
>> Furthermore, it generates false positives. The script is also hard to
>> read and understand, and is thereby difficult to maintain.
>>
>> This patch replaces the shell script with an implementation in Python,
>> which:
>>     (a) detects the same bugs, but does not report previous false positives
>>     (b) additionally detects broken references in Kconfig and all
>>         non-Kconfig files, such as Kbuild, .[cSh], .txt, .sh, defconfig, etc.
>>     (c) is up to 75 times faster than the shell script
>>     (d) only checks files under version control ('git ls-files')
>
> (The shell script is .git unaware. If you happen to have one or more
> branches with "Kconfig" in their name, as I do, it generates a lot of
> noise on stderr.)

Do you prefer to use os.walk() then? I just don't want to assume that
the script is called in a clean tree. 'git ls-files' avoids to filter
files. How do you solve this issue in your script?

>> The new script reduces the runtime on my machine (i7-2620M, 8GB RAM, SSD)
>> from 3m47s to 0m3s, and reports 939 broken identifiers in Linux v3.17-rc1;
>> 420 additional reports of which 16 are located in Kconfig files,
>> 287 in defconfigs, 63 in ./Documentation, 1 in Kbuild.
>>
>> Moreover, we intentionally include references in comments, which have been
>> ignored until now. Such comments may be leftovers of features that have
>> been removed or renamed in Kconfig (e.g., ``#endif /* CONFIG_MPC52xx */´´).
>> These references can be misleading and should be removed or replaced.
>>
>> Note that the output format changed from (file list <tab> feature) to
>> (feature <tab> file list) as it simplifies the detection of the Kconfig
>> feature for long file lists.
>>
>> Signed-off-by: Valentin Rothberg <valentinrothberg@...il.com>
>> Signed-off-by: Stefan Hengelein <stefan.hengelein@....de>
>> ---
>> Changelog:
>> v2: Fix of regular expressions
>> v3: Changelog replacement, and add changes of v2
>> v4: Based on comments from Paul Bolle <pebolle@...cali.nl>
>>   - Inclusion of all non-Kconfig files, such as .txt, .sh, etc.
>>   - Changes of regular expressions
>>   - Increases additional reports from 49 to 229 compared to v3
>>   - Change of output format from (file list <tab> feature) to
>>         (feature <tab> file list)·
>> v5: Only analyze files under version control ('git ls-files')
>> v6: Cover features with numbers and small letters (e.g., 4xx)
>> v7: Add changes of v6 (lost 'git add') and filter FOO/BAR features
>> ---
>>  scripts/checkkconfigsymbols.py | 138 +++++++++++++++++++++++++++++++++++++++++
>>  scripts/checkkconfigsymbols.sh |  59 ------------------
>>  2 files changed, 138 insertions(+), 59 deletions(-)
>>  create mode 100644 scripts/checkkconfigsymbols.py
>>  delete mode 100755 scripts/checkkconfigsymbols.sh
>>
>> diff --git a/scripts/checkkconfigsymbols.py b/scripts/checkkconfigsymbols.py
>> new file mode 100644
>> index 0000000..01bf9c4
>> --- /dev/null
>> +++ b/scripts/checkkconfigsymbols.py
>> @@ -0,0 +1,138 @@
>> +#!/usr/bin/env python
>> +
>> +"""Find Kconfig identifiers that are referenced but not defined."""
>> +
>> +# (c) 2014 Valentin Rothberg <valentinrothberg@...il.com>
>> +# (c) 2014 Stefan Hengelein <stefan.hengelein@....de>
>> +#
>> +# Licensed under the terms of the GNU GPL License version 2
>> +
>> +
>> +import os
>> +import re
>> +from subprocess import Popen, PIPE, STDOUT
>> +
>> +
>> +# regex expressions
>> +OPERATORS = r"&|\(|\)|\||\!"
>> +FEATURE = r"(?:\w*[A-Z0-9]\w*){2,}"
>> +DEF = r"^\s*(?:menu){,1}config\s+(" + FEATURE + r")\s*"
>> +EXPR = r"(?:" + OPERATORS + r"|\s|" + FEATURE + r")+"
>> +STMT = r"^\s*(?:if|select|depends\s+on)\s+" + EXPR
>
> Could please make that "depends on"? Yes, it seems the yacc grammar
> accepts any amount of whitespace, but that doesn't make it right to use
> anything other than a single space. (Can the yacc grammar be tweaked to
> see "depends on" as one, well, token?)

I don't know if yacc can do that. Usually the lexer trims whitespaces.
If I change the regex to "depends on", we will miss potential
statements as Kconfig accepts multiple spaces between the "depends"
and the "on".

>> +
>> +# regex objects
>> +REGEX_FILE_KCONFIG = re.compile(r".*Kconfig[\.\w+\-]*$")
>> +REGEX_FEATURE = re.compile(r"(" + FEATURE + r")")
>> +REGEX_SOURCE_FEATURE = re.compile(r"(?:D|\W|\b)+CONFIG_(" + FEATURE + r")")
>
> That should be "-D", because now you get a hit on
>     TPS6507X_ADCONFIG_CONVERT_TS
>
> and friends. What does \W do, by the way?

(?:\W|\b)+[D]{,1}CONFIG_... will do the trick. "-D" would fail in
getting DCONFIG_ in the build files. "\W" matches not "\w", which is
[A-Za-z0-9_].

>> +REGEX_KCONFIG_DEF = re.compile(DEF)
>> +REGEX_KCONFIG_EXPR = re.compile(EXPR)
>> +REGEX_KCONFIG_STMT = re.compile(STMT)
>> +REGEX_KCONFIG_HELP = re.compile(r"^\s+(help|---help---)\s*$")
>> +REGEX_FILTER_FEATURES = re.compile(r"[A-Za-z0-9]$")
>> +
>> +
>> +def main():
>> +    """Main function of this module."""
>> +    source_files = []
>> +    kconfig_files = []
>> +    defined_features = set()
>> +    referenced_features = dict()  # {feature: [files]}
>> +
>> +    # use 'git ls-files' to get the worklist
>> +    pop = Popen("git ls-files", stdout=PIPE, stderr=STDOUT, shell=True)
>> +    (stdout, _) = pop.communicate()  # wait until finished
>> +    if len(stdout) > 0 and stdout[-1] == "\n":
>> +        stdout = stdout[:-1]
>> +
>> +    for gitfile in stdout.rsplit("\n"):
>> +        if ".git" in gitfile or "ChangeLog" in gitfile or \
>> +                os.path.isdir(gitfile):
>
> (The only directories in the git tree are a few symlinks:
>     arch/arm/boot/dts/include/dt-bindings
>     arch/metag/boot/dts/include/dt-bindings
>     arch/mips/boot/dts/include/dt-bindings
>     arch/powerpc/boot/dts/include/dt-bindings
>
> Filtering out symlinks makes sense anyway. But that's probably not worth
> the effort.)
>
> You might also consider filtering out "Next/merge.log". It tends to have
> references to Kconfig macros. But it's only a few hits anyway.

Thanks. I will put ".log" in

>> +            continue
>> +        if REGEX_FILE_KCONFIG.match(gitfile):
>> +            kconfig_files.append(gitfile)
>> +        else:
>> +            # all non-Kconfig files are checked for consistency
>> +            source_files.append(gitfile)
>> +
>> +    for sfile in source_files:
>> +        parse_source_file(sfile, referenced_features)
>> +
>> +    for kfile in kconfig_files:
>> +        parse_kconfig_file(kfile, defined_features, referenced_features)
>> +
>> +    print "Undefined symbol used\tFile list"
>> +    for feature in sorted(referenced_features):
>> +        # filter some false positives
>> +        if feature == "FOO" or feature == "BAR" or \
>> +                feature == "FOO_BAR":
>> +            continue
>> +        if feature not in defined_features:
>> +            if feature.endswith("_MODULE"):
>> +                # avoid false positives for kernel modules
>> +                if feature[:-len("_MODULE")] in defined_features:
>> +                    continue
>> +            files = referenced_features.get(feature)
>> +            print "%s\t%s" % (feature, ", ".join(files))
>> +
>> +
>> +def parse_source_file(sfile, referenced_features):
>> +    """Parse @sfile for referenced Kconfig features."""
>> +    lines = []
>> +    with open(sfile, "r") as stream:
>> +        lines = stream.readlines()
>> +
>> +    for line in lines:
>> +        if not "CONFIG_" in line:
>> +            continue
>> +        features = REGEX_SOURCE_FEATURE.findall(line)
>> +        for feature in features:
>> +            if not REGEX_FILTER_FEATURES.search(feature):
>> +                continue
>> +            sfiles = referenced_features.get(feature, set())
>> +            sfiles.add(sfile)
>> +            referenced_features[feature] = sfiles
>> +
>> +
>> +def get_features_in_line(line):
>> +    """Return mentioned Kconfig features in @line."""
>> +    return REGEX_FEATURE.findall(line)
>> +
>> +
>> +def parse_kconfig_file(kfile, defined_features, referenced_features):
>> +    """Parse @kfile and update feature definitions and references."""
>> +    lines = []
>> +    skip = False
>> +
>> +    with open(kfile, "r") as stream:
>> +        lines = stream.readlines()
>> +
>> +    for i in range(len(lines)):
>> +        line = lines[i]
>> +        line = line.strip('\n')
>> +        line = line.split("#")[0]  # ignore comments
>> +
>> +        if REGEX_KCONFIG_DEF.match(line):
>> +            feature_def = REGEX_KCONFIG_DEF.findall(line)
>> +            defined_features.add(feature_def[0])
>> +            skip = False
>> +        elif REGEX_KCONFIG_HELP.match(line):
>> +            skip = True
>> +        elif skip:
>> +            # ignore content of help messages
>> +            pass
>> +        elif REGEX_KCONFIG_STMT.match(line):
>> +            features = get_features_in_line(line)
>> +            # multi-line statements
>> +            while line.endswith("\\"):
>> +                i += 1
>> +                line = lines[i]
>> +                line = line.strip('\n')
>> +                features.extend(get_features_in_line(line))
>> +            for feature in set(features):
>> +                paths = referenced_features.get(feature, set())
>> +                paths.add(kfile)
>> +                referenced_features[feature] = paths
>> +
>> +
>> +if __name__ == "__main__":
>> +    main()
>>[...]
>
> This seems to find, roughly, what my local perl script finds. It does
> skip references to Kconfig macros in the Kconfig help texts and
> comments: grep for CONFIG_ITANIUM_ASTEP_SPECIFIC as an example. But
> there are so few of those that it's probable not worth the trouble to
> check for them too.
>
> A few test show the speedup is especially nice with the entire tree in
> cache: run time drops from over four minutes to just under five seconds
> here. Provided you look into my comments, this is:
>
> Acked-by: Paul Bolle <pebolle@...cali.nl>

Thank you,
 Valentin Rothberg

>
> Thanks,
>
>
> Paul Bolle
>
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