linux-kernel - Re: [RFC] clang: 'unused-function' warning on static inline functions

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Date:   Wed, 7 Jun 2017 17:24:13 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Matthias Kaehlcke <mka@...omium.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Christoph Hellwig <hch@....de>, Jens Axboe <axboe@...nel.dk>,
        David Rientjes <rientjes@...gle.com>,
        Douglas Anderson <dianders@...omium.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Mark Brown <broonie@...nel.org>,
        David Miller <davem@...emloft.net>,
        Tom Herbert <tom@...bertland.com>
Subject: Re: [RFC] clang: 'unused-function' warning on static inline
 functions

On Wed, 7 Jun 2017 13:36:27 -0700
Linus Torvalds <torvalds@...ux-foundation.org> wrote:

> On Wed, Jun 7, 2017 at 12:43 PM, Arnd Bergmann <arnd@...db.de> wrote:
> >
> > The main reason I see for it is that a lot of the unused inline functions
> > in C files are mistakes,  
> 
> Bah. Blah blah blah.
> 
> The clang warnign doesn't actually really buy us anything, and it's a
> completely pointless difference to gcc.
> 
> I'm not in the least interested in supporting these kinds of pointless
> differences.
> 
> The people who are interested in making the kernel compile well with
> clang should care about the things that matter, not annoying people
> with idiotic patches.
> 
> So stop the idiotic patches.  When clang actually adds _value_, that's
> one thing. Right now it's just stupid noise.
> 
> For some reason compiler people think that "more warnings are good".
> No. They are not. More noise without any value is absolutely not good,
> and an unused inline function si by definition not something we care
> about.
> 
> Really. Fit the clang noise. Get clang to generate good code.
> 
> Once clang has actually proven itself, and we haev years of clang
> under our belt, and clang isn't just a toy and a source of bugs and
> pointless warnings as far as kernel builds are concerned, THEN we can
> start talking about actually making use of clang features.
> 
> Right now it should be about "don't be a f*cking pain in the arse!"
> 

Personally, I don't find the unused static inline function warning that
helpful either. But the only worry I have to totally ignoring them, is
that they could contain buggy code, which may either be cut-and-pasted
into code that is used, or one day used, and then inject buggy code.

But other than that, I pretty much agree with your assessment on this
one.

-- Steve