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 <avkras...@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
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