Re: [PATCH v3 16/18] vhost: don't bother with copying iovec in handle_tx()

[Michael S. Tsirkin]

On Wed, Feb 04, 2015 at 06:40:07AM +, Al Viro wrote:
> From: Al Viro 
> 
> just advance the msg.msg_iter and be done with that.
> 
> Cc: Michael S. Tsirkin 
> Cc: kvm@vger.kernel.org
> Cc: virtualizat...@lists.linux-foundation.org
> Signed-off-by: Al Viro 

Acked-by: Michael S. Tsirkin 

> ---
>  drivers/vhost/net.c | 9 +
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index 6906f76..d86cc9b 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -336,7 +336,7 @@ static void handle_tx(struct vhost_net *net)
>  {
>   struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
>   struct vhost_virtqueue *vq = &nvq->vq;
> - unsigned out, in, s;
> + unsigned out, in;
>   int head;
>   struct msghdr msg = {
>   .msg_name = NULL,
> @@ -395,16 +395,17 @@ static void handle_tx(struct vhost_net *net)
>   break;
>   }
>   /* Skip header. TODO: support TSO. */
> - s = move_iovec_hdr(vq->iov, nvq->hdr, hdr_size, out);
>   len = iov_length(vq->iov, out);
>   iov_iter_init(&msg.msg_iter, WRITE, vq->iov, out, len);
> + iov_iter_advance(&msg.msg_iter, hdr_size);
>   /* Sanity check */
> - if (!len) {
> + if (!iov_iter_count(&msg.msg_iter)) {
>   vq_err(vq, "Unexpected header len for TX: "
>  "%zd expected %zd\n",
> -iov_length(nvq->hdr, s), hdr_size);
> +len, hdr_size);
>   break;
>   }
> + len = iov_iter_count(&msg.msg_iter);
>  
>   zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
>  && (nvq->upend_idx + 1) % UIO_MAXIOV !=
> -- 
> 2.1.4
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[PATCH v3 16/18] vhost: don't bother with copying iovec in handle_tx()

[Al Viro]

From: Al Viro 

just advance the msg.msg_iter and be done with that.

Cc: Michael S. Tsirkin 
Cc: kvm@vger.kernel.org
Cc: virtualizat...@lists.linux-foundation.org
Signed-off-by: Al Viro 
---
 drivers/vhost/net.c | 9 +
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 6906f76..d86cc9b 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -336,7 +336,7 @@ static void handle_tx(struct vhost_net *net)
 {
struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
struct vhost_virtqueue *vq = &nvq->vq;
-   unsigned out, in, s;
+   unsigned out, in;
int head;
struct msghdr msg = {
.msg_name = NULL,
@@ -395,16 +395,17 @@ static void handle_tx(struct vhost_net *net)
break;
}
/* Skip header. TODO: support TSO. */
-   s = move_iovec_hdr(vq->iov, nvq->hdr, hdr_size, out);
len = iov_length(vq->iov, out);
iov_iter_init(&msg.msg_iter, WRITE, vq->iov, out, len);
+   iov_iter_advance(&msg.msg_iter, hdr_size);
/* Sanity check */
-   if (!len) {
+   if (!iov_iter_count(&msg.msg_iter)) {
vq_err(vq, "Unexpected header len for TX: "
   "%zd expected %zd\n",
-  iov_length(nvq->hdr, s), hdr_size);
+  len, hdr_size);
break;
}
+   len = iov_iter_count(&msg.msg_iter);
 
zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
   && (nvq->upend_idx + 1) % UIO_MAXIOV !=
-- 
2.1.4

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