From mboxrd@z Thu Jan 1 00:00:00 1970 From: BVK Chaitanya Subject: Re: [PATCH] serialize suspend-resume process Date: Thu, 31 Jul 2008 17:27:24 +0530 Message-ID: <4891A8A4.7010506@symantec.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Keir Fraser Cc: Xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org Keir Fraser wrote: > On 31/7/08 12:09, "BVK Chaitanya" wrote: >> >> Below patch makes suspend-resume process serialized. > > It's already supposed to be serialised, and there's a loop in xen_suspend() > to deal with up to one queued suspend request. Your patch may deal with an > arbitrary number of queued suspend requests, but a sane dom0 control stack > should never issue more than one suspend request in a suspend-resume cycle. > Yes, but there must be a way for dom0 to know that suspend-resume cycle is completed. Currently dom0 only gets suspend completed notification -- as part of shutdown hypercall -- but no resume (xenbus_suspend_cancel) completed notification. If dom0 issues second suspend request before resume is completed a _new_ kthread is started and will proceed with xen_suspend in parallel. I saw this hitting BUG_ON in netfront_accelerator_add_watch. Am i missing anything? regards, -- bvk-chaitanya