Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030783AbbDWT1k (ORCPT ); Thu, 23 Apr 2015 15:27:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42231 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030493AbbDWT1i (ORCPT ); Thu, 23 Apr 2015 15:27:38 -0400 Date: Thu, 23 Apr 2015 21:27:19 +0200 From: Thomas Huth To: Greg Kurz Cc: Rusty Russell , "Michael S. Tsirkin" , Cornelia Huck , linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: Re: [PATCH v5 6/8] virtio: add explicit big-endian support to memory accessors Message-ID: <20150423212719.4b7f9507@thh440s> In-Reply-To: <20150423152712.11795.29245.stgit@bahia.local> References: <20150423152608.11795.4373.stgit@bahia.local> <20150423152712.11795.29245.stgit@bahia.local> Organization: Red Hat MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3355 Lines: 105 On Thu, 23 Apr 2015 17:29:06 +0200 Greg Kurz wrote: > The current memory accessors logic is: > - little endian if little_endian > - native endian (i.e. no byteswap) if !little_endian > > If we want to fully support cross-endian vhost, we also need to be > able to convert to big endian. > > Instead of changing the little_endian argument to some 3-value enum, this > patch changes the logic to: > - little endian if little_endian > - big endian if !little_endian > > The native endian case is handled by all users with a trivial helper. This > patch doesn't change any functionality, nor it does add overhead. > > Signed-off-by: Greg Kurz > --- > > Changes since v4: > - style fixes (I have chosen if ... else in most places to stay below > 80 columns, with the notable exception of the vhost helper which gets > shorten in a later patch) > > drivers/net/macvtap.c | 5 ++++- > drivers/net/tun.c | 5 ++++- > drivers/vhost/vhost.h | 2 +- > include/linux/virtio_byteorder.h | 24 ++++++++++++++---------- > include/linux/virtio_config.h | 5 ++++- > include/linux/vringh.h | 2 +- > 6 files changed, 28 insertions(+), 15 deletions(-) > > diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c > index a2f2958..6cf6b3e 100644 > --- a/drivers/net/macvtap.c > +++ b/drivers/net/macvtap.c > @@ -51,7 +51,10 @@ struct macvtap_queue { > > static inline bool macvtap_is_little_endian(struct macvtap_queue *q) > { > - return q->flags & MACVTAP_VNET_LE; > + if (q->flags & MACVTAP_VNET_LE) > + return true; > + else > + return virtio_legacy_is_little_endian(); simply: return (q->flags & MACVTAP_VNET_LE) || virtio_legacy_is_little_endian(); ? > } > > static inline u16 macvtap16_to_cpu(struct macvtap_queue *q, __virtio16 val) > diff --git a/drivers/net/tun.c b/drivers/net/tun.c > index 3c3d6c0..5b044d4 100644 > --- a/drivers/net/tun.c > +++ b/drivers/net/tun.c > @@ -208,7 +208,10 @@ struct tun_struct { > > static inline bool tun_is_little_endian(struct tun_struct *tun) > { > - return tun->flags & TUN_VNET_LE; > + if (tun->flags & TUN_VNET_LE) > + return true; > + else > + return virtio_legacy_is_little_endian(); dito? > } > > static inline u16 tun16_to_cpu(struct tun_struct *tun, __virtio16 val) > diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h > index 6a49960..954c657 100644 > --- a/drivers/vhost/vhost.h > +++ b/drivers/vhost/vhost.h > @@ -175,7 +175,7 @@ static inline bool vhost_has_feature(struct vhost_virtqueue *vq, int bit) > > static inline bool vhost_is_little_endian(struct vhost_virtqueue *vq) > { > - return vhost_has_feature(vq, VIRTIO_F_VERSION_1); > + return vhost_has_feature(vq, VIRTIO_F_VERSION_1) ? true : virtio_legacy_is_little_endian(); > } That line is way longer than 80 characters ... may I suggest to switch at least here to: return vhost_has_feature(vq, VIRTIO_F_VERSION_1) || virtio_legacy_is_little_endian(); ? Apart from the cosmetics, the patch looks good to me. Thomas -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/