From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753370Ab1EEI5h (ORCPT ); Thu, 5 May 2011 04:57:37 -0400 Received: from mx1.redhat.com ([209.132.183.28]:63345 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751744Ab1EEI5f (ORCPT ); Thu, 5 May 2011 04:57:35 -0400 Date: Thu, 5 May 2011 11:56:56 +0300 From: "Michael S. Tsirkin" To: Stefan Hajnoczi Cc: linux-kernel@vger.kernel.org, Krishna Kumar , Carsten Otte , lguest@lists.ozlabs.org, Shirley Ma , kvm@vger.kernel.org, linux-s390@vger.kernel.org, netdev@vger.kernel.org, habanero@linux.vnet.ibm.com, Heiko Carstens , virtualization@lists.linux-foundation.org, steved@us.ibm.com, Christian Borntraeger , Tom Lendacky , Martin Schwidefsky , linux390@de.ibm.com Subject: Re: [PATCH 07/18] virtio ring: inline function to check for events Message-ID: <20110505085656.GC17647@redhat.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 05, 2011 at 09:34:46AM +0100, Stefan Hajnoczi wrote: > On Wed, May 4, 2011 at 9:51 PM, Michael S. Tsirkin wrote: > > With the new used_event and avail_event and features, both > > host and guest need similar logic to check whether events are > > enabled, so it helps to put the common code in the header. > > > > Note that Xen has similar logic for notification hold-off > > in include/xen/interface/io/ring.h with req_event and req_prod > > corresponding to event_idx + 1 and new_idx respectively. > > +1 comes from the fact that req_event and req_prod in Xen start at 1, > > while event index in virtio starts at 0. > > > > Signed-off-by: Michael S. Tsirkin > > --- > >  include/linux/virtio_ring.h |   14 ++++++++++++++ > >  1 files changed, 14 insertions(+), 0 deletions(-) > > > > diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h > > index f791772..2a3b0ea 100644 > > --- a/include/linux/virtio_ring.h > > +++ b/include/linux/virtio_ring.h > > @@ -124,6 +124,20 @@ static inline unsigned vring_size(unsigned int num, unsigned long align) > >                + sizeof(__u16) * 3 + sizeof(struct vring_used_elem) * num; > >  } > > > > +/* The following is used with USED_EVENT_IDX and AVAIL_EVENT_IDX */ > > +/* Assuming a given event_idx value from the other size, if > > s/other size/other side/ ? > > Stefan Exactly. Good catch, thanks. -- MST