From: Jason Wang <jasowang@redhat.com>
Date: Fri, 24 May 2019 08:12:13 +0000 (-0400)
Subject: vhost: generalize adding used elem
X-Git-Tag: v5.4-rc1~533^2~15
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=1ab5d1385af40272ca44a5cd38af7e13da6ed847;p=platform%2Fkernel%2Flinux-rpi.git

vhost: generalize adding used elem

Use one generic vhost_copy_to_user() instead of two dedicated
accessor. This will simplify the conversion to fine grain
accessors. About 2% improvement of PPS were seen during vitio-user
txonly test.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 3f3eac4..3fb58015 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -2273,16 +2273,7 @@ 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;
 	}