On 2018/12/14 上午3:41, Michael S. Tsirkin wrote:
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 <jasowang@xxxxxxxxxx>
The reason we did it like this is because it was faster.
Want to try benchmarking before we change it?
Faster is a good side effect of such conversion. Otherwise we need two
new fine grain memory accessor.
But, anyway, I can test its impact.
Thanks
---
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
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