[RFC PATCH v3 08/13] virtio/vsock: fetch length for SEQPACKET record

Arseny Krasnov
2021-01-25T12:51:35Z

This adds transport callback which tries to fetch record begin marker
from socket's rx queue. It is called from af_vsock.c before reading data
packets of record.

Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
---
include/linux/virtio_vsock.h | 1 +
net/vmw_vsock/virtio_transport_common.c | 33 +++++++++++++++++++++++++
2 files changed, 34 insertions(+)

diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index 7f0ef5204e33..af8705ea8b95 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -84,6 +84,7 @@ virtio_transport_dgram_dequeue(struct vsock_sock *vsk,
struct msghdr *msg,
size_t len, int flags);

+size_t virtio_transport_seqpacket_seq_get_len(struct vsock_sock *vsk);
s64 virtio_transport_stream_has_data(struct vsock_sock *vsk);
s64 virtio_transport_stream_has_space(struct vsock_sock *vsk);

diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index e66ec39445ff..dcce35d7b462 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -420,6 +420,39 @@ static size_t virtio_transport_drop_until_seq_begin(struct virtio_vsock_sock *vv
return bytes_dropped;
}

+size_t virtio_transport_seqpacket_seq_get_len(struct vsock_sock *vsk)
+{
+ struct virtio_vsock_sock *vvs = vsk->trans;
+ struct virtio_vsock_pkt *pkt;
+ size_t bytes_dropped;
+
+ spin_lock_bh(&vvs->rx_lock);
+
+ /* Fetch all orphaned 'RW', packets, and
+ * send credit update.
+ */
+ bytes_dropped = virtio_transport_drop_until_seq_begin(vvs);
+
+ if (list_empty(&vvs->rx_queue))
+ goto out;
+
+ pkt = list_first_entry(&vvs->rx_queue, struct virtio_vsock_pkt, list);
+
+ vvs->user_read_copied = 0;
+ vvs->user_read_seq_len = le32_to_cpu(pkt->hdr.flags);
+ virtio_transport_del_n_free_pkt(pkt);
+out:
+ spin_unlock_bh(&vvs->rx_lock);
+
+ if (bytes_dropped)
+ virtio_transport_send_credit_update(vsk,
+ VIRTIO_VSOCK_TYPE_SEQPACKET,
+ NULL);
+
+ return vvs->user_read_seq_len;
+}
+EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_seq_get_len);
+
static ssize_t virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
struct msghdr *msg,
size_t user_buf_len)
--
2.25.1