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Re: [RFC][PATCH] bug: Add _ONCE logic to report_bug()

From Ingo Molnar <mingo@kernel.org>
Newsgroups linux.kernel
Subject Re: [RFC][PATCH] bug: Add _ONCE logic to report_bug()
Date 2017-02-25 10:20 +0100
Message-ID <teGGd-5Fx-3@gated-at.bofh.it> (permalink)
References <te1D4-1LK-9@gated-at.bofh.it> <tem4N-7KI-21@gated-at.bofh.it> <teGwy-5C9-11@gated-at.bofh.it>
Organization linux.* mail to news gateway

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* Peter Zijlstra <peterz@infradead.org> wrote:

> 
> Josh suggested moving the _ONCE logic inside the trap handler, using a
> bit in the bug_entry::flags field, avoiding the need for the extra
> variable.

This looks interesting, as the _ONCE() methods of warning are far more 
user-friendly than WARN() spam.

> Sadly this only works for WARN_ON_ONCE(), since the others have
> printk() statements prior to triggering the trap.

Which one is problematic to convert, WARN_ONCE()?

> Still, this saves some text and data:
> 
>   text            data     bss    dec              hex    filename
>   10469505        4443448  843776 15756729         f06db9 defconfig-build/vmlinux-ud0
>   10452803        4442616  843776 15739195         f0293b defconfig-build/vmlinux-ud0-once
> 
> (Only compile tested on x86_64 so far.)

That looks pretty sweet, as various almost never triggered _ONCE() checks tend to 
disturb the generated machine code quite a bit ...

Thanks,

	Ingo

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Thread

[PATCH] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-02-23 14:30 +0100
  Re: [PATCH] x86: Implement __WARN using UD0 Arjan van de Ven <arjan@linux.intel.com> - 2017-02-23 15:20 +0100
    Re: [PATCH] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-02-23 16:00 +0100
      Re: [PATCH] x86: Implement __WARN using UD0 Ingo Molnar <mingo@kernel.org> - 2017-02-24 09:00 +0100
        Re: [PATCH] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-02-24 09:40 +0100
          Re: [PATCH] x86: Implement __WARN using UD0 Ingo Molnar <mingo@kernel.org> - 2017-02-24 10:20 +0100
            Re: [PATCH] x86: Implement __WARN using UD0 Borislav Petkov <bp@alien8.de> - 2017-02-24 10:50 +0100
              Re: [PATCH] x86: Implement __WARN using UD0 "H. Peter Anvin" <hpa@zytor.com> - 2017-02-24 12:50 +0100
            Re: [PATCH] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-02-24 12:50 +0100
              Re: [PATCH] x86: Implement __WARN using UD0 Borislav Petkov <bp@alien8.de> - 2017-02-25 11:50 +0100
                Re: [PATCH] x86: Implement __WARN using UD0 hpa@zytor.com - 2017-02-25 19:00 +0100
                Re: [PATCH] x86: Implement __WARN using UD0 Borislav Petkov <bp@alien8.de> - 2017-02-25 20:40 +0100
                Re: [PATCH] x86: Implement __WARN using UD0 Borislav Petkov <bp@alien8.de> - 2017-02-25 21:40 +0100
                Re: [PATCH] x86: Implement __WARN using UD0 hpa@zytor.com - 2017-02-25 21:50 +0100
          Re: [PATCH] x86: Implement __WARN using UD0 hpa@zytor.com - 2017-02-24 10:20 +0100
          Re: [PATCH] x86: Implement __WARN using UD0 hpa@zytor.com - 2017-02-24 10:50 +0100
  Re: [PATCH] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-02-23 15:20 +0100
    Re: [PATCH] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-02-23 16:00 +0100
    Re: [PATCH] x86: Implement __WARN using UD0 hpa@zytor.com - 2017-02-23 16:20 +0100
      Re: [PATCH] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-02-23 16:30 +0100
        Re: [PATCH] x86: Implement __WARN using UD0 hpa@zytor.com - 2017-02-23 16:40 +0100
          Re: [PATCH] x86: Implement __WARN using UD0 Borislav Petkov <bp@alien8.de> - 2017-02-23 17:10 +0100
  Re: [PATCH] x86: Implement __WARN using UD0 Josh Poimboeuf <jpoimboe@redhat.com> - 2017-02-23 15:20 +0100
    Re: [PATCH] x86: Implement __WARN using UD0 Borislav Petkov <bp@alien8.de> - 2017-02-23 15:30 +0100
    Re: [PATCH] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-02-23 15:40 +0100
  [PATCH -v2] x86: Implement __WARN using UD0 Peter Zijlstra <peterz@infradead.org> - 2017-02-24 12:20 +0100
    [RFC][PATCH] bug: Add _ONCE logic to report_bug() Peter Zijlstra <peterz@infradead.org> - 2017-02-25 10:10 +0100
      Re: [RFC][PATCH] bug: Add _ONCE logic to report_bug() Ingo Molnar <mingo@kernel.org> - 2017-02-25 10:20 +0100
        Re: [RFC][PATCH] bug: Add _ONCE logic to report_bug() Peter Zijlstra <peterz@infradead.org> - 2017-02-25 11:50 +0100

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