From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:50042)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <richard.weiyang@gmail.com>) id 1agZRA-0003jN-Qh
	for qemu-devel@nongnu.org; Thu, 17 Mar 2016 11:02:12 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <richard.weiyang@gmail.com>) id 1agZR6-0001Kk-Ns
	for qemu-devel@nongnu.org; Thu, 17 Mar 2016 11:02:08 -0400
Date: Thu, 17 Mar 2016 15:01:49 +0000
From: Wei Yang <richard.weiyang@gmail.com>
Message-ID: <20160317150149.GA1772@vultr.guest>
References: <1455152067-19900-1-git-send-email-richard.weiyang@gmail.com>
	<56E9433C.1040503@msgid.tls.msk.ru> <56E94914.1040803@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <56E94914.1040803@redhat.com>
Subject: Re: [Qemu-devel] [PATCH] vfio/pci: replace 1 with PCI_CAP_LIST_NEXT
 to make code self-explain
Reply-To: Wei Yang <richard.weiyang@gmail.com>
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-trivial@nongnu.org, alex.williamson@redhat.com, Michael Tokarev <mjt@tls.msk.ru>, qemu-devel@nongnu.org, Wei Yang <richard.weiyang@gmail.com>

On Wed, Mar 16, 2016 at 12:52:52PM +0100, Paolo Bonzini wrote:
>
>
>On 16/03/2016 12:27, Michael Tokarev wrote:
>>> >      for (tmp = pdev->config[PCI_CAPABILITY_LIST]; tmp;
>>> > -         tmp = pdev->config[tmp + 1]) {
>>> > +         tmp = pdev->config[tmp + PCI_CAP_LIST_NEXT]) {
>>> > -    next = pdev->config[pos + 1];
>>> > +    next = pdev->config[pos + PCI_CAP_LIST_NEXT];
>> Hmm. I'm not sure the new version is better, to me "+1" reads
>> easier than the new symbolic constant variant.
>> 
>> If it were something like pdev->config[PCI_CAP_LIST_NEXT], that'd be
>> nice, but not "pos + PCI_CAP_LIST_NEXT".
>> 
>> But again, I'm not pci config space expert and don't understand
>> the basics :)

Thanks Michael for your comment. By using the macro, audience is more easy to
understand it tries to get the position of next capability.

>
>Each capability is a node of a linked list, and the position of the next
>capability is at offset 1 inside the capability (here it is at offset 1
>from the tmp or pos base).  I think the patch is an improvement.
>

Thanks Paolo for your reply. :-) 

>Paolo

-- 
Wei Yang
Help you, Help me