From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH net-next 1/3] vhost: generalize adding used elem Date: Thu, 13 Dec 2018 14:41:08 -0500 Message-ID: <20181213144027-mutt-send-email-mst@kernel.org> References: <20181213101022.12475-1-jasowang@redhat.com> <20181213101022.12475-2-jasowang@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: Jason Wang Return-path: Content-Disposition: inline In-Reply-To: <20181213101022.12475-2-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, Dec 13, 2018 at 06:10:20PM +0800, Jason Wang wrote: > Use one generic vhost_copy_to_user() instead of two dedicated > accessor. This will simplify the conversion to fine grain accessors. > > Signed-off-by: Jason Wang The reason we did it like this is because it was faster. Want to try benchmarking before we change it? > --- > drivers/vhost/vhost.c | 11 +---------- > 1 file changed, 1 insertion(+), 10 deletions(-) > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index 3a5f81a66d34..1c54ec1b82f8 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -2164,16 +2164,7 @@ static int __vhost_add_used_n(struct vhost_virtqueue *vq, > > start = vq->last_used_idx & (vq->num - 1); > used = vq->used->ring + start; > - if (count == 1) { > - if (vhost_put_user(vq, heads[0].id, &used->id)) { > - vq_err(vq, "Failed to write used id"); > - return -EFAULT; > - } > - if (vhost_put_user(vq, heads[0].len, &used->len)) { > - vq_err(vq, "Failed to write used len"); > - return -EFAULT; > - } > - } else if (vhost_copy_to_user(vq, used, heads, count * sizeof *used)) { > + if (vhost_copy_to_user(vq, used, heads, count * sizeof *used)) { > vq_err(vq, "Failed to write used"); > return -EFAULT; > } > -- > 2.17.1