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Date: Wed, 14 Aug 2013 11:50:14 +0200
From: Ingo Molnar <mingo@kernel.org>
To: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Andy Lutomirski <luto@amacapital.net>,
        Pavel Emelyanov <xemul@parallels.com>, Matt Mackall <mpm@selenic.com>,
        Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>,
        Marcelo Tosatti <mtosatti@redhat.com>,
        KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Peter Zijlstra <peterz@infradead.org>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH -mm] mm: Unify pte_to_pgoff and pgoff_to_pte helpers
Message-ID: <20130814095014.GA10849@gmail.com>
References: <20130814070059.GJ2869@moon>
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 <20130814003336.0fb2a275.akpm@linux-foundation.org>
 <20130814074333.GM2869@moon>
 <20130814010856.0098398b.akpm@linux-foundation.org>
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* Cyrill Gorcunov <gorcunov@gmail.com> wrote:

> On Wed, Aug 14, 2013 at 01:08:56AM -0700, Andrew Morton wrote:
> > > 
> > > > Can it be written in C with types and proper variable names and such
> > > > radical stuff?
> > > 
> > > Could you elaborate? You mean inline helper or macro with type checks?
> > 
> > /*
> >  * description goes here
> >  */
> > static inline pteval_t pte_bfop(pteval_t val, int rightshift, ...)
> > {
> > 	...
> > }
> > 
> > So much better!  We really should only implement code in a macro if it
> > *has* to be done as a macro and I don't think that's the case here?
> 
> Well, I'll have to check if it really doesn't generate additional 
> instructions in generated code, since it's hotpath. I'll ping back once 
> things are done.

An __always_inline should never do that.

Thanks,

	Ingo