[RFC PATCH net-next v6 13/14] virtio/vsock: implement datagram support

[Amery Hung]

From: Bobby Eshleman <bobby.eshleman@xxxxxxxxxxxxx>

This commit implements datagram support with a new version of
->dgram_allow().

Additionally, it drops virtio_transport_dgram_allow() as an exported
symbol because it is no longer used in other transports.

Signed-off-by: Bobby Eshleman <bobby.eshleman@xxxxxxxxxxxxx>
Signed-off-by: Amery Hung <amery.hung@xxxxxxxxxxxxx>
---
 include/linux/virtio_vsock.h            |  1 -
 net/vmw_vsock/virtio_transport.c        | 22 +++++++++++++++++++++-
 net/vmw_vsock/virtio_transport_common.c |  6 ------
 3 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index 4408749febd2..fe8fa0a9669d 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -222,7 +222,6 @@ void virtio_transport_notify_buffer_size(struct vsock_sock *vsk, u64 *val);
 u64 virtio_transport_stream_rcvhiwat(struct vsock_sock *vsk);
 bool virtio_transport_stream_is_active(struct vsock_sock *vsk);
 bool virtio_transport_stream_allow(u32 cid, u32 port);
-bool virtio_transport_dgram_allow(u32 cid, u32 port);
 
 int virtio_transport_connect(struct vsock_sock *vsk);
 
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index 4891b845fcde..4e1ed3b11e26 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -63,6 +63,7 @@ struct virtio_vsock {
 
 	u32 guest_cid;
 	bool seqpacket_allow;
+	bool dgram_allow;
 
 	/* These fields are used only in tx path in function
 	 * 'virtio_transport_send_pkt_work()', so to save
@@ -492,6 +493,21 @@ static bool virtio_transport_msgzerocopy_allow(void)
 	return true;
 }
 
+static bool virtio_transport_dgram_allow(u32 cid, u32 port)
+{
+	struct virtio_vsock *vsock;
+	bool dgram_allow;
+
+	dgram_allow = false;
+	rcu_read_lock();
+	vsock = rcu_dereference(the_virtio_vsock);
+	if (vsock)
+		dgram_allow = vsock->dgram_allow;
+	rcu_read_unlock();
+
+	return dgram_allow;
+}
+
 static bool virtio_transport_seqpacket_allow(u32 remote_cid);
 
 static struct virtio_transport virtio_transport = {
@@ -753,6 +769,9 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
 	if (virtio_has_feature(vdev, VIRTIO_VSOCK_F_SEQPACKET))
 		vsock->seqpacket_allow = true;
 
+	if (virtio_has_feature(vdev, VIRTIO_VSOCK_F_DGRAM))
+		vsock->dgram_allow = true;
+
 	vdev->priv = vsock;
 
 	ret = virtio_vsock_vqs_init(vsock);
@@ -850,7 +869,8 @@ static struct virtio_device_id id_table[] = {
 };
 
 static unsigned int features[] = {
-	VIRTIO_VSOCK_F_SEQPACKET
+	VIRTIO_VSOCK_F_SEQPACKET,
+	VIRTIO_VSOCK_F_DGRAM
 };
 
 static struct virtio_driver virtio_vsock_driver = {
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index a571b575fde9..52f671287fe3 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -1010,12 +1010,6 @@ bool virtio_transport_stream_allow(u32 cid, u32 port)
 }
 EXPORT_SYMBOL_GPL(virtio_transport_stream_allow);
 
-bool virtio_transport_dgram_allow(u32 cid, u32 port)
-{
-	return false;
-}
-EXPORT_SYMBOL_GPL(virtio_transport_dgram_allow);
-
 int virtio_transport_connect(struct vsock_sock *vsk)
 {
 	struct virtio_vsock_pkt_info info = {
-- 
2.20.1