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Date:   Mon, 8 Jun 2020 02:45:50 -0400
From:   "Michael S. Tsirkin" <mst@redhat.com>
To:     Jason Wang <jasowang@redhat.com>
Cc:     linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        virtualization@lists.linux-foundation.org, netdev@vger.kernel.org,
        eperezma@redhat.com
Subject: Re: [PATCH RFC v5 13/13] vhost: drop head based APIs
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On Mon, Jun 08, 2020 at 11:57:48AM +0800, Jason Wang wrote:
> 
> On 2020/6/7 下午10:11, Michael S. Tsirkin wrote:
> > Everyone's using buf APIs, no need for head based ones anymore.
> > 
> > Signed-off-by: Michael S. Tsirkin<mst@redhat.com>
> > ---
> >   drivers/vhost/vhost.c | 36 ++++++++----------------------------
> >   drivers/vhost/vhost.h | 12 ------------
> >   2 files changed, 8 insertions(+), 40 deletions(-)
> > 
> > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> > index 72ee55c810c4..e6931b760b61 100644
> > --- a/drivers/vhost/vhost.c
> > +++ b/drivers/vhost/vhost.c
> > @@ -2299,12 +2299,12 @@ static int fetch_buf(struct vhost_virtqueue *vq)
> >   	return 1;
> >   }
> > -/* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */
> > +/* Revert the effect of fetch_buf. Useful for error handling. */
> > +static
> >   void vhost_discard_vq_desc(struct vhost_virtqueue *vq, int n)
> >   {
> >   	vq->last_avail_idx -= n;
> >   }
> > -EXPORT_SYMBOL_GPL(vhost_discard_vq_desc);
> 
> 
> The same question as previous version.
> 
> Do we need to rewind cached descriptor here?
> 
> Thanks

Good point.  This needs more thought, we need to also
rewind the avail idx each time we flush the descriptor cache.

-- 
MST