diff mbox series

[RFC,v1,06/12] vsock/virtio: non-linear skb handling for TAP dev

Message ID ebee740a-95df-ed52-6274-a9340e8dc9d2@sberdevices.ru
State New
Headers
Series vsock: MSG_ZEROCOPY flag support |

Commit Message

Arseniy Krasnov Feb. 6, 2023, 6:59 a.m. UTC 
  For TAP device new skb is created and data from the current skb is
copied to it. This adds copying data from non-linear skb to new
the skb.

Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
---
 net/vmw_vsock/virtio_transport_common.c | 43 +++++++++++++++++++++++--
 1 file changed, 40 insertions(+), 3 deletions(-)

-- 
2.25.1

Comments

Stefano Garzarella Feb. 16, 2023, 2:30 p.m. UTC | #1 
On Mon, Feb 06, 2023 at 06:59:21AM +0000, Arseniy Krasnov wrote:
>For TAP device new skb is created and data from the current skb is
>copied to it. This adds copying data from non-linear skb to new
>the skb.
>
>Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
>---
> net/vmw_vsock/virtio_transport_common.c | 43 +++++++++++++++++++++++--
> 1 file changed, 40 insertions(+), 3 deletions(-)
>
>diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
>index a1581c77cf84..05ce97b967ad 100644
>--- a/net/vmw_vsock/virtio_transport_common.c
>+++ b/net/vmw_vsock/virtio_transport_common.c
>@@ -101,6 +101,39 @@ virtio_transport_alloc_skb(struct virtio_vsock_pkt_info *info,
> 	return NULL;
> }
>
>+static void virtio_transport_copy_nonlinear_skb(struct sk_buff *skb,
>+						void *dst,
>+						size_t len)
>+{
>+	size_t rest_len = len;
>+
>+	while (rest_len && virtio_vsock_skb_has_frags(skb)) {
>+		struct bio_vec *curr_vec;
>+		size_t curr_vec_end;
>+		size_t to_copy;
>+		int curr_frag;
>+		int curr_offs;
>+
>+		curr_frag = VIRTIO_VSOCK_SKB_CB(skb)->curr_frag;
>+		curr_offs = VIRTIO_VSOCK_SKB_CB(skb)->frag_off;
>+		curr_vec = &skb_shinfo(skb)->frags[curr_frag];
>+
>+		curr_vec_end = curr_vec->bv_offset + curr_vec->bv_len;
>+		to_copy = min(rest_len, (size_t)(curr_vec_end - curr_offs));
>+
>+		memcpy(dst, page_to_virt(curr_vec->bv_page) + curr_offs,
>+		       to_copy);
>+
>+		rest_len -= to_copy;
>+		VIRTIO_VSOCK_SKB_CB(skb)->frag_off += to_copy;
>+
>+		if (VIRTIO_VSOCK_SKB_CB(skb)->frag_off == (curr_vec_end)) {
>+			VIRTIO_VSOCK_SKB_CB(skb)->curr_frag++;
>+			VIRTIO_VSOCK_SKB_CB(skb)->frag_off = 0;
>+		}
>+	}
>+}
>+
> /* Packet capture */
> static struct sk_buff *virtio_transport_build_skb(void *opaque)
> {
>@@ -109,7 +142,6 @@ static struct sk_buff *virtio_transport_build_skb(void *opaque)
> 	struct af_vsockmon_hdr *hdr;
> 	struct sk_buff *skb;
> 	size_t payload_len;
>-	void *payload_buf;
>
> 	/* A packet could be split to fit the RX buffer, so we can retrieve
> 	 * the payload length from the header and the buffer pointer taking
>@@ -117,7 +149,6 @@ static struct sk_buff *virtio_transport_build_skb(void *opaque)
> 	 */
> 	pkt_hdr = virtio_vsock_hdr(pkt);
> 	payload_len = pkt->len;
>-	payload_buf = pkt->data;
>
> 	skb = alloc_skb(sizeof(*hdr) + sizeof(*pkt_hdr) + payload_len,
> 			GFP_ATOMIC);
>@@ -160,7 +191,13 @@ static struct sk_buff *virtio_transport_build_skb(void *opaque)
> 	skb_put_data(skb, pkt_hdr, sizeof(*pkt_hdr));
>
> 	if (payload_len) {
>-		skb_put_data(skb, payload_buf, payload_len);
>+		if (skb_is_nonlinear(skb)) {
>+			void *data = skb_put(skb, payload_len);
>+
>+			virtio_transport_copy_nonlinear_skb(skb, data, payload_len);
>+		} else {
>+			skb_put_data(skb, pkt->data, payload_len);
>+		}

Ehm I'm a bit confused. Maybe we need to rename the sk_buffs involved in
this function (pre-existing).

We have `pkt` that is the original sk_buff, and `skb` that it is 
allocated in this function, so IIUC we should check if `pkt` is 
nonlinear and copy its payload into `skb`, so we should do this 
(untested) chage:

@@ -367,10 +367,10 @@ static struct sk_buff *virtio_transport_build_skb(void *opaque)
         skb_put_data(skb, pkt_hdr, sizeof(*pkt_hdr));

         if (payload_len) {
-               if (skb_is_nonlinear(skb)) {
+               if (skb_is_nonlinear(pkt)) {
                         void *data = skb_put(skb, payload_len);

-                       virtio_transport_copy_nonlinear_skb(skb, data, payload_len);
+                       virtio_transport_copy_nonlinear_skb(pkt, data, payload_len);
                 } else {
                         skb_put_data(skb, pkt->data, payload_len);
                 }

Thanks,
Stefano

> 	}
>
> 	return skb;
>-- 
>2.25.1
diff mbox series

Patch

diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index a1581c77cf84..05ce97b967ad 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -101,6 +101,39 @@  virtio_transport_alloc_skb(struct virtio_vsock_pkt_info *info,
 	return NULL;
 }
 
+static void virtio_transport_copy_nonlinear_skb(struct sk_buff *skb,
+						void *dst,
+						size_t len)
+{
+	size_t rest_len = len;
+
+	while (rest_len && virtio_vsock_skb_has_frags(skb)) {
+		struct bio_vec *curr_vec;
+		size_t curr_vec_end;
+		size_t to_copy;
+		int curr_frag;
+		int curr_offs;
+
+		curr_frag = VIRTIO_VSOCK_SKB_CB(skb)->curr_frag;
+		curr_offs = VIRTIO_VSOCK_SKB_CB(skb)->frag_off;
+		curr_vec = &skb_shinfo(skb)->frags[curr_frag];
+
+		curr_vec_end = curr_vec->bv_offset + curr_vec->bv_len;
+		to_copy = min(rest_len, (size_t)(curr_vec_end - curr_offs));
+
+		memcpy(dst, page_to_virt(curr_vec->bv_page) + curr_offs,
+		       to_copy);
+
+		rest_len -= to_copy;
+		VIRTIO_VSOCK_SKB_CB(skb)->frag_off += to_copy;
+
+		if (VIRTIO_VSOCK_SKB_CB(skb)->frag_off == (curr_vec_end)) {
+			VIRTIO_VSOCK_SKB_CB(skb)->curr_frag++;
+			VIRTIO_VSOCK_SKB_CB(skb)->frag_off = 0;
+		}
+	}
+}
+
 /* Packet capture */
 static struct sk_buff *virtio_transport_build_skb(void *opaque)
 {
@@ -109,7 +142,6 @@  static struct sk_buff *virtio_transport_build_skb(void *opaque)
 	struct af_vsockmon_hdr *hdr;
 	struct sk_buff *skb;
 	size_t payload_len;
-	void *payload_buf;
 
 	/* A packet could be split to fit the RX buffer, so we can retrieve
 	 * the payload length from the header and the buffer pointer taking
@@ -117,7 +149,6 @@  static struct sk_buff *virtio_transport_build_skb(void *opaque)
 	 */
 	pkt_hdr = virtio_vsock_hdr(pkt);
 	payload_len = pkt->len;
-	payload_buf = pkt->data;
 
 	skb = alloc_skb(sizeof(*hdr) + sizeof(*pkt_hdr) + payload_len,
 			GFP_ATOMIC);
@@ -160,7 +191,13 @@  static struct sk_buff *virtio_transport_build_skb(void *opaque)
 	skb_put_data(skb, pkt_hdr, sizeof(*pkt_hdr));
 
 	if (payload_len) {
-		skb_put_data(skb, payload_buf, payload_len);
+		if (skb_is_nonlinear(skb)) {
+			void *data = skb_put(skb, payload_len);
+
+			virtio_transport_copy_nonlinear_skb(skb, data, payload_len);
+		} else {
+			skb_put_data(skb, pkt->data, payload_len);
+		}
 	}
 
 	return skb;