[PATCH net-next v4 6/9] vsock: add API call for data ready

[Arseniy Krasnov <AVKrasnov@sberdevices.ru>]

This adds 'vsock_data_ready()' which must be called by transport to kick
sleeping data readers. It checks for SO_RCVLOWAT value before waking
user, thus preventing spurious wake ups. Based on 'tcp_data_ready()' logic.

Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
---
 include/net/af_vsock.h   |  1 +
 net/vmw_vsock/af_vsock.c | 10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index d609a088cb27..568a87c5e0d0 100644
--- a/include/net/af_vsock.h
+++ b/include/net/af_vsock.h
@@ -78,6 +78,7 @@ struct vsock_sock {
 s64 vsock_stream_has_data(struct vsock_sock *vsk);
 s64 vsock_stream_has_space(struct vsock_sock *vsk);
 struct sock *vsock_create_connected(struct sock *parent);
+void vsock_data_ready(struct sock *sk);
 
 /**** TRANSPORT ****/
 
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index b5cbc849844b..85a665253e84 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -882,6 +882,16 @@ s64 vsock_stream_has_space(struct vsock_sock *vsk)
 }
 EXPORT_SYMBOL_GPL(vsock_stream_has_space);
 
+void vsock_data_ready(struct sock *sk)
+{
+	struct vsock_sock *vsk = vsock_sk(sk);
+
+	if (vsock_stream_has_data(vsk) >= sk->sk_rcvlowat ||
+	    sock_flag(sk, SOCK_DONE))
+		sk->sk_data_ready(sk);
+}
+EXPORT_SYMBOL_GPL(vsock_data_ready);
+
 static int vsock_release(struct socket *sock)
 {
 	__vsock_release(sock->sk, 0);
-- 
2.25.1