[PATCH RFC net-next v5 07/14] virtio/vsock: add common datagram send path

Bobby Eshleman
2023-07-19T00:50:19Z

This commit implements the common function
virtio_transport_dgram_enqueue for enqueueing datagrams. It does not add
usage in either vhost or virtio yet.

Signed-off-by: Bobby Eshleman <bobby.eshleman@bytedance.com>
---
net/vmw_vsock/virtio_transport_common.c | 76 ++++++++++++++++++++++++++++++++-
1 file changed, 75 insertions(+), 1 deletion(-)

diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index ffcbdd77feaa..3bfaff758433 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -819,7 +819,81 @@ virtio_transport_dgram_enqueue(struct vsock_sock *vsk,
struct msghdr *msg,
size_t dgram_len)
{
- return -EOPNOTSUPP;
+ /* Here we are only using the info struct to retain style uniformity
+ * and to ease future refactoring and merging.
+ */
+ struct virtio_vsock_pkt_info info_stack = {
+ .op = VIRTIO_VSOCK_OP_RW,
+ .msg = msg,
+ .vsk = vsk,
+ .type = VIRTIO_VSOCK_TYPE_DGRAM,
+ };
+ const struct virtio_transport *t_ops;
+ struct virtio_vsock_pkt_info *info;
+ struct sock *sk = sk_vsock(vsk);
+ struct virtio_vsock_hdr *hdr;
+ u32 src_cid, src_port;
+ struct sk_buff *skb;
+ void *payload;
+ int noblock;
+ int err;
+
+ info = &info_stack;
+
+ if (dgram_len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE)
+ return -EMSGSIZE;
+
+ t_ops = virtio_transport_get_ops(vsk);
+ if (unlikely(!t_ops))
+ return -EFAULT;
+
+ /* Unlike some of our other sending functions, this function is not
+ * intended for use without a msghdr.
+ */
+ if (WARN_ONCE(!msg, "vsock dgram bug: no msghdr found for dgram enqueue\n"))
+ return -EFAULT;
+
+ noblock = msg->msg_flags & MSG_DONTWAIT;
+
+ /* Use sock_alloc_send_skb to throttle by sk_sndbuf. This helps avoid
+ * triggering the OOM.
+ */
+ skb = sock_alloc_send_skb(sk, dgram_len + VIRTIO_VSOCK_SKB_HEADROOM,
+ noblock, &err);
+ if (!skb)
+ return err;
+
+ skb_reserve(skb, VIRTIO_VSOCK_SKB_HEADROOM);
+
+ src_cid = t_ops->transport.get_local_cid();
+ src_port = vsk->local_addr.svm_port;
+
+ hdr = virtio_vsock_hdr(skb);
+ hdr->type = cpu_to_le16(info->type);
+ hdr->op = cpu_to_le16(info->op);
+ hdr->src_cid = cpu_to_le64(src_cid);
+ hdr->dst_cid = cpu_to_le64(remote_addr->svm_cid);
+ hdr->src_port = cpu_to_le32(src_port);
+ hdr->dst_port = cpu_to_le32(remote_addr->svm_port);
+ hdr->flags = cpu_to_le32(info->flags);
+ hdr->len = cpu_to_le32(dgram_len);
+
+ skb_set_owner_w(skb, sk);
+
+ payload = skb_put(skb, dgram_len);
+ err = memcpy_from_msg(payload, msg, dgram_len);
+ if (err)
+ return err;
+
+ trace_virtio_transport_alloc_pkt(src_cid, src_port,
+ remote_addr->svm_cid,
+ remote_addr->svm_port,
+ dgram_len,
+ info->type,
+ info->op,
+ 0);
+
+ return t_ops->send_pkt(skb);
}
EXPORT_SYMBOL_GPL(virtio_transport_dgram_enqueue);

--
2.30.2