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OpenCloudOS-Kernel
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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>
This commit is contained in:
Jason Wang 2019-05-24 04:12:13 -04:00 committed by Michael S. Tsirkin
parent c1ea02f15a
commit 1ab5d1385a
1 changed files with 1 additions and 10 deletions
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11
drivers/vhost/vhost.c
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@ -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;
}