From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Dunlap Subject: Re: [PATCH] xen: domain_update_node_affinity: Correct the ASSERT Date: Mon, 4 Aug 2014 15:50:47 +0100 Message-ID: <53DF9DC7.2000207@eu.citrix.com> References: <1406904759-3833-1-git-send-email-julien.grall@linaro.org> <53DBCA8B020000780002886D@mail.emea.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta5.messagelabs.com ([195.245.231.135]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1XEJbW-0003cC-ET for xen-devel@lists.xenproject.org; Mon, 04 Aug 2014 14:51:14 +0000 In-Reply-To: <53DBCA8B020000780002886D@mail.emea.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich , Julien Grall Cc: Juergen Gross , Keir Fraser , ian.campbell@citrix.com, tim@xen.org, Ian Jackson , George Dunlap , stefano.stabellini@citrix.com, xen-devel@lists.xenproject.org List-Id: xen-devel@lists.xenproject.org On 08/01/2014 04:12 PM, Jan Beulich wrote: >>>> On 01.08.14 at 16:52, wrote: >> --- a/xen/common/domain.c >> +++ b/xen/common/domain.c >> @@ -449,7 +449,7 @@ void domain_update_node_affinity(struct domain *d) >> } >> /* Filter out non-online cpus */ >> cpumask_and(dom_cpumask, dom_cpumask, online); >> - ASSERT(!cpumask_empty(dom_cpumask)); >> + ASSERT( !d->vcpu || !d->vcpu[0] || !cpumask_empty(dom_cpumask)); >> /* And compute the intersection between hard, online and soft */ >> cpumask_and(dom_cpumask_soft, dom_cpumask_soft, dom_cpumask); >> > > Actually, with sched_move_domain() having > > /* Do we have vcpus already? If not, no need to update node-affinity */ > if ( d->vcpu ) > domain_update_node_affinity(d); > > it should really just be _that_ if() condition to get extended, and the > ASSERT() left alone altogether. Or, if any other path can be proven > to possibly reach the function with no vCPU allocated (I just went > through them and didn't spot any), then it should really be an early > bail from the function rather than a pointlessly complicated ASSERT() > expression. (And for the record, your expression has a coding style > violation anyway in that it begins with a space.) I think changing the if() was what Julien started with; but overall I think that it makes more sense to update the assumption of the code in question than to require all the callers to be careful not to trip over it. Doing an early bail might make sense as well. -George