linux-kernel - Re: [Ksummit-discuss] checkkpatch (in)sanity ?

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Message-ID: <20160828075632.GA1852@p183.telecom.by>
Date:   Sun, 28 Aug 2016 10:56:33 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     "Levin, Alexander" <alexander.levin@...izon.com>
Cc:     Joe Perches <joe@...ches.com>,
        "ksummit-discuss@...ts.linuxfoundation.org" 
        <ksummit-discuss@...ts.linuxfoundation.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Sasha Levin <levinsasha928@...il.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [Ksummit-discuss] checkkpatch (in)sanity ?

On Sat, Aug 27, 2016 at 09:06:13PM -0400, Levin, Alexander via Ksummit-discuss wrote:
> 3. This one is somewhat subjective: scripts/checkpatch.pl is a massive blob of
> perl code that a fair amount of people don't know how to deal with. In 4.8 it's
> 6142 lines, making it the 124th largest source file in the kernel, well within
> the top 1% of source files in the kernel.
> 
> This combination of size/language pushes people away from being involved in
> what is supposed to be a central tool and gives them a reason to never use
> it again after they see results they don't agree with (rather than fixing it).

It is a textbook example of what's wrong with Perl. Instead of parsing
C code like compilers do, the script is one big pile of regexes.
It mostly works ("doing its job" in perlspeak) because people mostly
follow the coding style.

Regarding individual warnings: some are good (RETURN_VOID, DATE_TIME,
USE_NEGATIVE_ERRNO), some are OK given kernel style of allocating memory
but the rationale is bogus (UNNECESSARY_CASTS, linking to userspace
example of malloc() returning "int"!).

And then there is ALLOC_SIZEOF_STRUCT which advocates "kmalloc(sizeof(*p))".

The problem is that c-h.pl generates noise in the commit history and
makes git-blame less useful than it can be.

I for one given up on it more or less since its introduction.