From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754734AbaCCTo3 (ORCPT ); Mon, 3 Mar 2014 14:44:29 -0500 Received: from e37.co.us.ibm.com ([32.97.110.158]:36278 "EHLO e37.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754239AbaCCTo2 (ORCPT ); Mon, 3 Mar 2014 14:44:28 -0500 Date: Mon, 3 Mar 2014 11:44:23 -0800 From: "Paul E. McKenney" To: mst@redhat.com Cc: linux-kernel@vger.kernel.org Subject: Question on vhost_has_feature() Message-ID: <20140303194422.GA17107@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14030319-7164-0000-0000-000006919A25 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Michael, Just curious about the purpose of the rcu_dereference_index_check() in vhost_has_feature(). I don't see how it fits in. The closest thing I see if the use in handle_rx(), where it selects vq->log or NULL. But in that case, I would expect the usual RCU usage pattern to wrap an rcu_dereference() around the vq->log. Enlightenment? Thanx, Paul