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Date: Wed, 14 Aug 2013 11:50:14 +0200
From: Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH -mm] mm: Unify pte_to_pgoff and pgoff_to_pte helpers
Message-ID: <20130814095014.GA10849@gmail.com>
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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>


* 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

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