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Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1

From	Ingo Molnar <mingo@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1
Date	2016-07-28 19:10 +0200
Message-ID	<rZWYN-M3-3@gated-at.bofh.it> (permalink)
References	(3 earlier) <nBeOl-7wr-1@gated-at.bofh.it> <rZL7k-14A-23@gated-at.bofh.it> <rZORz-3Ef-9@gated-at.bofh.it> <rZPaW-3LV-11@gated-at.bofh.it> <rZWP8-s6-9@gated-at.bofh.it>
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* Ingo Molnar <mingo@kernel.org> wrote:

> But that's my point, I believe the false positive rate is pretty low in fact, due 
> to three factors:
> 
>  - 90% of the warnings get fixed by developers, we never see them upstream
> 
>  - I'd say a majority (say 70%) of the remaining warnings are flagging 'complexity 
>    bugs'
>  
>  - only a residual 3% are obnoxious ones.
> 
> But these remaining 3% are the ones we are seeing again and again in various 
> compiler output, so we tend to get a subjective impression that this warning 
> produces countless false positives.

And note that I am well aware of the real risk this poses: people will ignore real 
warnings if there are so many residual false positives.

I think this approach worked pretty well for perf:

> So I *think* the better option would be to do what we are doing in the perf 
> tooling: force a build error for these warnings (by default, with an option 
> available to make it build). That flushes them out and also makes it sure that 
> those questionable sequences of code never get upstream to begin with.

... but might not be appropriate for the kernel which is a 2 orders of magnitude 
larger code base.

Thanks,

	Ingo

Thread

Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1 Borislav Petkov <bp@alien8.de> - 2016-07-28 06:30 +0200
  Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1 Ingo Molnar <mingo@kernel.org> - 2016-07-28 10:30 +0200
    Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1 Borislav Petkov <bp@alien8.de> - 2016-07-28 10:50 +0200
      Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1 Ingo Molnar <mingo@kernel.org> - 2016-07-28 19:00 +0200
        Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1 Ingo Molnar <mingo@kernel.org> - 2016-07-28 19:10 +0200
      Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1 Markus Trippelsdorf <markus@trippelsdorf.de> - 2016-07-28 20:10 +0200
    Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1 Linus Torvalds <torvalds@linux-foundation.org> - 2016-07-28 21:10 +0200
      Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1 Linus Torvalds <torvalds@linux-foundation.org> - 2016-07-28 21:10 +0200
        Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1 Ingo Molnar <mingo@kernel.org> - 2016-07-28 22:30 +0200
      Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1 Linus Torvalds <torvalds@linux-foundation.org> - 2016-07-28 23:30 +0200
        Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1 Borislav Petkov <bp@alien8.de> - 2016-07-29 12:20 +0200
          Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1 Arnd Bergmann <arnd@arndb.de> - 2016-07-29 12:40 +0200
          Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1 Linus Torvalds <torvalds@linux-foundation.org> - 2016-07-29 20:30 +0200
        Re: [PATCH] Kbuild: Move -Wmaybe-uninitialized to W=1 Arnd Bergmann <arnd@arndb.de> - 2016-07-29 12:20 +0200

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