From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [RFC PATCH 1/3] kvm: keep track of which task is running a KVM vcpu Date: Sun, 05 Dec 2010 14:59:49 +0200 Message-ID: <4CFB8CC5.50902@redhat.com> References: <20101202144129.4357fe00@annuminas.surriel.com> <20101202144324.4a79263b@annuminas.surriel.com> <20101203121746.GE27994@linux.vnet.ibm.com> <4CF8FBAA.7000807@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: vatsa@linux.vnet.ibm.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar , Anthony Liguori To: Rik van Riel Return-path: Received: from mx1.redhat.com ([209.132.183.28]:2057 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755547Ab0LENAO (ORCPT ); Sun, 5 Dec 2010 08:00:14 -0500 In-Reply-To: <4CF8FBAA.7000807@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 12/03/2010 04:16 PM, Rik van Riel wrote: > On 12/03/2010 07:17 AM, Srivatsa Vaddagiri wrote: >> On Thu, Dec 02, 2010 at 02:43:24PM -0500, Rik van Riel wrote: >>> mutex_lock(&vcpu->mutex); >>> + vcpu->task = current; >> >> Shouldn't we grab reference to current task_struct before storing a >> pointer to >> it? > > That should not be needed, since current cannot go away without > setting vcpu->task back to NULL in vcpu_put. > However, you do reference vcpu->task from other contexts. So some sort of safe reference is needed. -- error compiling committee.c: too many arguments to function