Date:	Wed, 08 Oct 2014 15:39:29 +0200
From:	Michal Marek <mmarek@...e.cz>
To:	Valentin Rothberg <valentinrothberg@...il.com>
CC:	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	linux-kbuild@...r.kernel.org, Paul Bolle <pebolle@...cali.nl>,
	Stefan Hengelein <stefan.hengelein@....de>
Subject: Re: [PATCH v8] checkkconfigsymbols.sh: reimplementation in python

On 2014-10-04 11:29, Valentin Rothberg wrote:
> On Wed, Oct 1, 2014 at 4:58 PM, Michal Marek <mmarek@...e.cz> wrote:
>> On 2014-09-29 19:05, 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 new script reduces the runtime on my machine (i7-2620M, 8GB RAM, SSD)
>>> from 3m47s to 0m3s, and reports 912 broken references in Linux v3.17-rc1;
>>> 424 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>
>>> Acked-by: Paul Bolle <pebolle@...cali.nl>
>>> ---
>>> 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
>>> v8: Based on comments from Paul Bolle <pebolle@...cali.nl>
>>>   - Fix of [D]{,1}CONFIG_ regex to exclude false positives
>>>   - Exclude ".log" files of analysis
>>>   - Filter "XXX" feature
>>> ---
>>>  scripts/checkkconfigsymbols.py | 139 +++++++++++++++++++++++++++++++++++++++++
>>>  scripts/checkkconfigsymbols.sh |  59 -----------------
>>>  2 files changed, 139 insertions(+), 59 deletions(-)
>>>  create mode 100644 scripts/checkkconfigsymbols.py
>>>  delete mode 100755 scripts/checkkconfigsymbols.sh
>>
>> Please make the new file executable as well.
>>
>>
>>> +    for gitfile in stdout.rsplit("\n"):
>>> +        if ".git" in gitfile or "ChangeLog" in gitfile or \
>>> +                ".log" in gitfile or os.path.isdir(gitfile):
>>> +            continue
>>
>> Can you also skip arch/*/configs? A significant part of the output are
>> defconfig files, but there is little value in reporting them. The stale
>> options will go away automatically as soon as the defconfig is refreshed.
> 
> What do you mean by "refreshed"?

Generated again with new Kconfig data.


> And how often are they refreshed? I
> think that reporting defconfigs helps to point to a problem, namely
> that features are just not present anymore.

Any given defconfig is outdated most of the time, so you could as well
list them all :). In most of the cases, it does not matter though,
thanks to the defaults in Kconfig files.

Michal
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