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[RFC,v4,02/17] vhost/vsock: read data from non-linear skb

Message ID 20230603204939.1598818-3-AVKrasnov@sberdevices.ru (mailing list archive)
State RFC
Headers show
Series vsock: MSG_ZEROCOPY flag support | expand

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netdev/series_format fail Series longer than 15 patches (and no cover letter)
netdev/tree_selection success Guessed tree name to be net-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 8 this patch: 8
netdev/cc_maintainers success CCed 7 of 7 maintainers
netdev/build_clang success Errors and warnings before: 8 this patch: 8
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 8 this patch: 8
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 35 lines checked
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netdev/source_inline success Was 0 now: 0

Commit Message

Arseniy Krasnov June 3, 2023, 8:49 p.m. UTC 
This adds copying to guest's virtio buffers from non-linear skbs. Such
skbs are created by protocol layer when MSG_ZEROCOPY flags is used. It
changes call of 'copy_to_iter()' to 'skb_copy_datagram_iter()'. Second
function can read data from non-linear skb.

See commit to 'net/vmw_vsock/virtio_transport_common.c' with the same
name for more details.

Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
---
 drivers/vhost/vsock.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

Comments

Bobby Eshleman June 12, 2023, 5:53 p.m. UTC | #1 
On Sat, Jun 03, 2023 at 11:49:24PM +0300, Arseniy Krasnov wrote:
> This adds copying to guest's virtio buffers from non-linear skbs. Such
> skbs are created by protocol layer when MSG_ZEROCOPY flags is used. It
> changes call of 'copy_to_iter()' to 'skb_copy_datagram_iter()'. Second
> function can read data from non-linear skb.
> 
> See commit to 'net/vmw_vsock/virtio_transport_common.c' with the same
> name for more details.
> 
> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
> ---
>  drivers/vhost/vsock.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> index 6578db78f0ae..b254aa4b756a 100644
> --- a/drivers/vhost/vsock.c
> +++ b/drivers/vhost/vsock.c
> @@ -156,7 +156,7 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
>  		}
>  
>  		iov_iter_init(&iov_iter, ITER_DEST, &vq->iov[out], in, iov_len);
> -		payload_len = skb->len;
> +		payload_len = skb->len - VIRTIO_VSOCK_SKB_CB(skb)->frag_off;
>  		hdr = virtio_vsock_hdr(skb);
>  
>  		/* If the packet is greater than the space available in the
> @@ -197,8 +197,10 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
>  			break;
>  		}
>  
> -		nbytes = copy_to_iter(skb->data, payload_len, &iov_iter);
> -		if (nbytes != payload_len) {
> +		if (skb_copy_datagram_iter(skb,
> +					   VIRTIO_VSOCK_SKB_CB(skb)->frag_off,
> +					   &iov_iter,
> +					   payload_len)) {
>  			kfree_skb(skb);
>  			vq_err(vq, "Faulted on copying pkt buf\n");
>  			break;
> @@ -212,13 +214,13 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
>  		vhost_add_used(vq, head, sizeof(*hdr) + payload_len);
>  		added = true;
>  
> -		skb_pull(skb, payload_len);
> +		VIRTIO_VSOCK_SKB_CB(skb)->frag_off += payload_len;
>  		total_len += payload_len;
>  
>  		/* If we didn't send all the payload we can requeue the packet
>  		 * to send it with the next available buffer.
>  		 */
> -		if (skb->len > 0) {
> +		if (VIRTIO_VSOCK_SKB_CB(skb)->frag_off < skb->len) {
>  			hdr->flags |= cpu_to_le32(flags_to_restore);
>  
>  			/* We are queueing the same skb to handle
> -- 
> 2.25.1
> 

LGTM.

Reviewed-by: Bobby Eshleman <bobby.eshleman@bytedance.com>
Stefano Garzarella June 26, 2023, 3:24 p.m. UTC | #2 
On Sat, Jun 03, 2023 at 11:49:24PM +0300, Arseniy Krasnov wrote:
>This adds copying to guest's virtio buffers from non-linear skbs. Such
>skbs are created by protocol layer when MSG_ZEROCOPY flags is used. It
>changes call of 'copy_to_iter()' to 'skb_copy_datagram_iter()'. Second
>function can read data from non-linear skb.
>
>See commit to 'net/vmw_vsock/virtio_transport_common.c' with the same
>name for more details.

I think it's okay if we report the same details here.

>
>Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
>---
> drivers/vhost/vsock.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
>diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
>index 6578db78f0ae..b254aa4b756a 100644
>--- a/drivers/vhost/vsock.c
>+++ b/drivers/vhost/vsock.c
>@@ -156,7 +156,7 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> 		}
>
> 		iov_iter_init(&iov_iter, ITER_DEST, &vq->iov[out], in, iov_len);
>-		payload_len = skb->len;
>+		payload_len = skb->len - VIRTIO_VSOCK_SKB_CB(skb)->frag_off;

Also here a variable should make the code more readable.

Stefano

> 		hdr = virtio_vsock_hdr(skb);
>
> 		/* If the packet is greater than the space available in the
>@@ -197,8 +197,10 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> 			break;
> 		}
>
>-		nbytes = copy_to_iter(skb->data, payload_len, &iov_iter);
>-		if (nbytes != payload_len) {
>+		if (skb_copy_datagram_iter(skb,
>+					   VIRTIO_VSOCK_SKB_CB(skb)->frag_off,
>+					   &iov_iter,
>+					   payload_len)) {
> 			kfree_skb(skb);
> 			vq_err(vq, "Faulted on copying pkt buf\n");
> 			break;
>@@ -212,13 +214,13 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
> 		vhost_add_used(vq, head, sizeof(*hdr) + payload_len);
> 		added = true;
>
>-		skb_pull(skb, payload_len);
>+		VIRTIO_VSOCK_SKB_CB(skb)->frag_off += payload_len;
> 		total_len += payload_len;
>
> 		/* If we didn't send all the payload we can requeue the packet
> 		 * to send it with the next available buffer.
> 		 */
>-		if (skb->len > 0) {
>+		if (VIRTIO_VSOCK_SKB_CB(skb)->frag_off < skb->len) {
> 			hdr->flags |= cpu_to_le32(flags_to_restore);
>
> 			/* We are queueing the same skb to handle
>-- 
>2.25.1
>
diff mbox series

Patch

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 6578db78f0ae..b254aa4b756a 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -156,7 +156,7 @@  vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
 		}
 
 		iov_iter_init(&iov_iter, ITER_DEST, &vq->iov[out], in, iov_len);
-		payload_len = skb->len;
+		payload_len = skb->len - VIRTIO_VSOCK_SKB_CB(skb)->frag_off;
 		hdr = virtio_vsock_hdr(skb);
 
 		/* If the packet is greater than the space available in the
@@ -197,8 +197,10 @@  vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
 			break;
 		}
 
-		nbytes = copy_to_iter(skb->data, payload_len, &iov_iter);
-		if (nbytes != payload_len) {
+		if (skb_copy_datagram_iter(skb,
+					   VIRTIO_VSOCK_SKB_CB(skb)->frag_off,
+					   &iov_iter,
+					   payload_len)) {
 			kfree_skb(skb);
 			vq_err(vq, "Faulted on copying pkt buf\n");
 			break;
@@ -212,13 +214,13 @@  vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
 		vhost_add_used(vq, head, sizeof(*hdr) + payload_len);
 		added = true;
 
-		skb_pull(skb, payload_len);
+		VIRTIO_VSOCK_SKB_CB(skb)->frag_off += payload_len;
 		total_len += payload_len;
 
 		/* If we didn't send all the payload we can requeue the packet
 		 * to send it with the next available buffer.
 		 */
-		if (skb->len > 0) {
+		if (VIRTIO_VSOCK_SKB_CB(skb)->frag_off < skb->len) {
 			hdr->flags |= cpu_to_le32(flags_to_restore);
 
 			/* We are queueing the same skb to handle