Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Fri, 7 Sep 2018 10:21:56 +0200 (CEST)
From:   Thomas Gleixner <tglx@linutronix.de>
To:     "Yang, Bin" <bin.yang@intel.com>
cc:     "mingo@kernel.org" <mingo@kernel.org>,
        "hpa@zytor.com" <hpa@zytor.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "peterz@infradead.org" <peterz@infradead.org>,
        "Gross, Mark" <mark.gross@intel.com>,
        "x86@kernel.org" <x86@kernel.org>,
        "Hansen, Dave" <dave.hansen@intel.com>
Subject: Re: [PATCH v3 4/5] x86/mm: optimize static_protection() by using
 overlap()
In-Reply-To: <cd73f43a15f06c720bb4907d2c424dfb3f0c8683.camel@intel.com>
Message-ID: <alpine.DEB.2.21.1809071019020.1402@nanos.tec.linutronix.de>
References: <1534814186-37067-1-git-send-email-bin.yang@intel.com>  <1534814186-37067-5-git-send-email-bin.yang@intel.com>  <alpine.DEB.2.21.1809041413070.3395@nanos.tec.linutronix.de>  <82fc8d80749f920c4a5107469924205d92037785.camel@intel.com> 
 <alpine.DEB.2.21.1809070943490.1402@nanos.tec.linutronix.de> <cd73f43a15f06c720bb4907d2c424dfb3f0c8683.camel@intel.com>
User-Agent: Alpine 2.21 (DEB 202 2017-01-01)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Fri, 7 Sep 2018, Yang, Bin wrote:
> On Fri, 2018-09-07 at 09:49 +0200, Thomas Gleixner wrote:
> > On Fri, 7 Sep 2018, Yang, Bin wrote:
> > > On Tue, 2018-09-04 at 14:22 +0200, Thomas Gleixner wrote:
> > > 
> > > I just write a test.c to compare the result between overlap() and
> > > original within().
> > 
> > You are right. Your version of doing the overlap exclusive works. I misread
> > the conditions. I still prefer doing inclusive checks because they are way
> > more obvious.
> 
> I am sorry for my poor english. What is "inclusive checks"?

Exlusive:    val >= start && val < end

Inclusive:   val >= start && val <= end

So the difference is that you feed exclusive with:

   end = start + size

and inclusive with

  end = start + size - 1

Thanks,

	tglx