From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ian Campbell <ian.campbell@citrix.com>
Subject: Re: [PATCH v4 7/8] xen/iommu: smmu: Advertise when the
 SMMU support coherent table walk
Date: Mon, 2 Mar 2015 16:24:07 +0000
Message-ID: <1425313447.24959.1.camel@citrix.com>
References: <1424890381-4225-1-git-send-email-julien.grall@linaro.org>
	<1424890381-4225-8-git-send-email-julien.grall@linaro.org>
	<1425301809.21151.9.camel@citrix.com> <54F48059.6000604@linaro.org>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path: <xen-devel-bounces@lists.xen.org>
Received: from mail6.bemta14.messagelabs.com ([193.109.254.103])
	by lists.xen.org with esmtp (Exim 4.72)
	(envelope-from <Ian.Campbell@citrix.com>) id 1YST8k-0003Wu-DH
	for xen-devel@lists.xenproject.org; Mon, 02 Mar 2015 16:24:18 +0000
In-Reply-To: <54F48059.6000604@linaro.org>
List-Unsubscribe: <http://lists.xen.org/cgi-bin/mailman/options/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xen.org>
List-Help: <mailto:xen-devel-request@lists.xen.org?subject=help>
List-Subscribe: <http://lists.xen.org/cgi-bin/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=subscribe>
Sender: xen-devel-bounces@lists.xen.org
Errors-To: xen-devel-bounces@lists.xen.org
To: Julien Grall <julien.grall@linaro.org>
Cc: xen-devel@lists.xenproject.org, manish.jaggi@caviumnetworks.com, stefano.stabellini@citrix.com, tim@xen.org
List-Id: xen-devel@lists.xenproject.org

On Mon, 2015-03-02 at 15:23 +0000, Julien Grall wrote:
> >> +	/* Find the last SMMU added and retrieve its features. */
> > 
> > This comment no longer applies, I think?
> 
> I think it's useful to have a comment explaining why we are retrieving
> the SMMU.

Sorry, I initially misread things and thought this was processing all
smmus.

> 
> >> +	spin_lock(&arm_smmu_devices_lock);
> >> +	list_for_each_entry(smmu, &arm_smmu_devices, list) {
> >> +		if (smmu->dev == &dev->dev)
> >> +			goto found;
> > 
> > Please try and avoid goto. In this case I think 
> >      {
> >          platform_features &= smmu->features;
> >          break;
> >      }
> 
> I though about this solution but it doesn't say if for some reason we
> miss to find the SMMU.

I think that's fine in this context. If it isn't on the list at this
point it might as well not exist and/or there would have been an error
somewhere else already.

> > 
> > within the if would be fine, combined with dropping the following BUG().
> > 
> > Alternatively you might prefer to provide a helper function to lookup an
> > smmu by &dev->dev.
> 
> I would like to keep the BUG(). Because this would be a mistake to not
> find the last SMMU added.

Sounds more like an ASSERT to me.

> I will move to an helper function.

Sure.