On Thu, 23 Apr 2015 21:27:19 +0200
Thomas Huth <thuth@xxxxxxxxxx> wrote:
> On Thu, 23 Apr 2015 17:29:06 +0200
> Greg Kurz <gkurz@xxxxxxxxxxxxxxxxxx> 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 <gkurz@xxxxxxxxxxxxxxxxxx>
> > ---
> >
> > 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();
>
> ?
ISTR that MST preferred the current notation, but I like either your
way or ?: (with linebreak) even better.
>
> > }
> >
(...)
> > 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();
I think the line will collapse in a further patch anyway.
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