From mboxrd@z Thu Jan 1 00:00:00 1970 From: Carsten Otte Subject: Re: [04/17] [PATCH] Add kvm arch-specific core code for kvm/ia64.-V8 Date: Tue, 01 Apr 2008 12:59:39 +0200 Message-ID: <47F2159B.5060709@de.ibm.com> References: <42DFA526FC41B1429CE7279EF83C6BDC01048245@pdsmsx415.ccr.corp.intel.com> <47F0FAA5.2090109@de.ibm.com> <42DFA526FC41B1429CE7279EF83C6BDC01048488@pdsmsx415.ccr.corp.intel.com> <47F1E9F8.6010801@de.ibm.com> <42DFA526FC41B1429CE7279EF83C6BDC0104870C@pdsmsx415.ccr.corp.intel.com> Reply-To: carsteno@de.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: carsteno@de.ibm.com, Avi Kivity , "Luck, Tony" , "Xu, Anthony" , Jes Sorensen , Akio Takebe , kvm-devel@lists.sourceforge.net, kvm-ia64-devel@lists.sourceforge.net, linux-ia64@vger.kernel.org, virtualization@lists.linux-foundation.org To: "Zhang, Xiantao" Return-path: In-Reply-To: <42DFA526FC41B1429CE7279EF83C6BDC0104870C@pdsmsx415.ccr.corp.intel.com> Sender: linux-ia64-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Zhang, Xiantao wrote: > Carsten Otte wrote: >> Zhang, Xiantao wrote: >>> Hi, Carsten >>> Why do you think it is racy? In this function, >>> target_vcpu->arch.launched should be set to 1 for the first run, and >>> keep its value all the time. Except the first IPI to wake up the >>> vcpu, all IPIs received by target vcpu should go into "else" >>> condition. So you mean the race condition exist in "else" code ? >> For example to lock against destroying that vcpu. Or, the waitqueue >> may become active after if (waitqueue_active()) and before >> wake_up_interruptible(). In that case, the target vcpu might sleep and >> not get waken up by the ipi. > I don't think it may cause issue, because the target vcpu at least can > be waken up by the timer interrupt. > > But as you said, x86 side also have the same race issue ? As far as I can tell, x86 does'nt have that race.