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Date:      Sun, 20 Nov 2011 17:37:33 +0100
From:      Attilio Rao <attilio@freebsd.org>
To:        Kostik Belousov <kostikbel@gmail.com>
Cc:        mdf@freebsd.org, "K. Macy" <kmacy@freebsd.org>, Alan Cox <alc@rice.edu>, Andriy Gapon <avg@freebsd.org>, freebsd-current@freebsd.org, Benjamin Kaduk <kaduk@mit.edu>, Penta Upa <bsdboot@gmail.com>
Subject:   Re: vm_page_t related KBI [Was: Re: panic at vm_page_wire with FreeBSD 9.0 Beta 3]
Message-ID:  <CAJ-FndD%2Bj6WKmsLW9Kv2nDKEJePe=js3xmmj6m6NW3eS1RZD-w@mail.gmail.com>
In-Reply-To: <CAJ-FndCZqwvbi2N=f=5TxkHH3gaKAGxipPoHBCFLqF=sLOTqdQ@mail.gmail.com>
References:  <20111105141306.GW50300@deviant.kiev.zoral.com.ua> <CAMBSHm86TaJnRRgmPA_t7tiPfQsPyoTqz3ymdHSY1H3t5G864Q@mail.gmail.com> <20111105151530.GX50300@deviant.kiev.zoral.com.ua> <4EB595FA.4020500@rice.edu> <20111106124331.GP50300@deviant.kiev.zoral.com.ua> <4EB81942.70501@rice.edu> <20111107193516.GA50300@deviant.kiev.zoral.com.ua> <CAJ-FndDsrVk7EjjtE=QuhaJE1_k7Q1BvQ%2BxriJPnGzLXJQr1sg@mail.gmail.com> <20111116084542.GY50300@deviant.kiev.zoral.com.ua> <CAJ-FndAwWzFJgpCdaaE=YkipZSCtE6Vb8-LEK2_qS=bVhRM3OQ@mail.gmail.com> <20111118105224.GB50300@deviant.kiev.zoral.com.ua> <CAJ-FndAULb9r-FVaBparSJVtoSEQuX7%2BwhCoBNdQi7n%2B=UpEdA@mail.gmail.com> <CAJ-FndCZqwvbi2N=f=5TxkHH3gaKAGxipPoHBCFLqF=sLOTqdQ@mail.gmail.com>

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2011/11/18 Attilio Rao <attilio@freebsd.org>:
> 2011/11/18 Attilio Rao <attilio@freebsd.org>:
>> 2011/11/18 Kostik Belousov <kostikbel@gmail.com>:
>>> On Fri, Nov 18, 2011 at 11:40:28AM +0100, Attilio Rao wrote:
>>>> 2011/11/16 Kostik Belousov <kostikbel@gmail.com>:
>>>> > On Tue, Nov 15, 2011 at 07:15:01PM +0100, Attilio Rao wrote:
>>>> >> 2011/11/7 Kostik Belousov <kostikbel@gmail.com>:
>>>> >> > On Mon, Nov 07, 2011 at 11:45:38AM -0600, Alan Cox wrote:
>>>> >> >> Ok. =C2=A0I'll offer one final suggestion. =C2=A0Please consider=
 an alternative
>>>> >> >> suffix to "func". =C2=A0Perhaps, "kbi" or "KBI". =C2=A0In other =
words, something
>>>> >> >> that hints at the function's reason for existing.
>>>> >> >
>>>> >> > Sure. Below is the extraction of only vm_page_lock() bits, togeth=
er
>>>> >> > with the suggested rename. When Attilio provides the promised sim=
plification
>>>> >> > of the mutex KPI, this can be reduced.
>>>> >>
>>>> >> My tentative patch is here:
>>>> >> http://www.freebsd.org/~attilio/mutexfileline.patch
>>>> >>
>>>> >> I need to make more compile testing later, but it already compiles
>>>> >> GENERIC + modules fine on HEAD.
>>>> >>
>>>> >> The patch provides a common entrypoint, option independent, for bot=
h
>>>> >> fast case and debug/compat case.
>>>> >> Additively, it almost entirely fixes the standard violation of the
>>>> >> reserved namespace, as you described (the notable exception being t=
he
>>>> >> macro used in the fast path, that I want to fix as well, but in a
>>>> >> separate commit).
>>>> >>
>>>> >> Now the file/line couplet can be passed to the "_" suffix variant o=
f
>>>> >> the flag functions.
>>>> > Yes, this is exactly KPI that I would use when available for the
>>>> > vm_page_lock() patch.
>>>> >
>>>> >>
>>>> >> eadler@ reviewed the mutex.h comment.
>>>> >>
>>>> >> Please let me know what you think about it, as long as we agree on =
the
>>>> >> patch I'll commit it.
>>>> > But I also agree with John that imposing large churn due to the elim=
ination
>>>> > of the '__' prefix is too late now. At least it will make the change
>>>> > non-MFCable. Besides, we already lived with the names for 10+ years.
>>>> >
>>>> > I will be happy to have the part of the patch that exports the mtx_X=
XX_(mtx,
>>>> > file, line) defines which can be used without taking care of LOCK_DE=
BUG
>>>> > or MUTEX_NOINLINE in the consumer code.
>>>>
>>>> Ok, this patch should just add the compat stub:
>>>> http://www.freebsd.org/~attilio/mutexfileline2.patch
>>> Am I right that I would use mtx_lock_(mtx, file, line) etc ?
>>> If yes, I am fine with it.
>>
>> Yes that is correct.
>>
>> However, I'm a bit confused on one aspect: would you mind using
>> _mtx_lock_flags() instead?
>> If you don't mind the "underscore namespace violation" I think I can
>> make a much smaller patch against HEAD for it.
>>
>> Otherwise, the one now posted should be ok.
>
> After thinking more about it, I think that is basically the shorter
> version I can came up with.
>
> Please consider:
> http://www.freebsd.org/~attilio/mutexfileline2.patch

This is now committed as r227758,227759, you can update your patch now.

Attilio


--=20
Peace can only be achieved by understanding - A. Einstein



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