vsock: SO_RCVLOWAT transport set callback

This adds transport specific callback for SO_RCVLOWAT, because in some
transports it may be difficult to know current available number of bytes
ready to read. Thus, when SO_RCVLOWAT is set, transport may reject it.

Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index 1c53c4c..d609a08 100644 (file)
--- a/include/net/af_vsock.h
+++ b/include/net/af_vsock.h
@@ -135,6 +135,7 @@ struct vsock_transport {
        u64 (*stream_rcvhiwat)(struct vsock_sock *);
        bool (*stream_is_active)(struct vsock_sock *);
        bool (*stream_allow)(u32 cid, u32 port);
+       int (*set_rcvlowat)(struct vsock_sock *vsk, int val);
 
        /* SEQ_PACKET. */
        ssize_t (*seqpacket_dequeue)(struct vsock_sock *vsk, struct msghdr *msg,

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index b4ee163..07c8f74 100644 (file)
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -2137,6 +2137,25 @@ out:
        return err;
 }
 
+static int vsock_set_rcvlowat(struct sock *sk, int val)
+{
+       const struct vsock_transport *transport;
+       struct vsock_sock *vsk;
+
+       vsk = vsock_sk(sk);
+
+       if (val > vsk->buffer_size)
+               return -EINVAL;
+
+       transport = vsk->transport;
+
+       if (transport && transport->set_rcvlowat)
+               return transport->set_rcvlowat(vsk, val);
+
+       WRITE_ONCE(sk->sk_rcvlowat, val ? : 1);
+       return 0;
+}
+
 static const struct proto_ops vsock_stream_ops = {
        .family = PF_VSOCK,
        .owner = THIS_MODULE,
@@ -2156,6 +2175,7 @@ static const struct proto_ops vsock_stream_ops = {
        .recvmsg = vsock_connectible_recvmsg,
        .mmap = sock_no_mmap,
        .sendpage = sock_no_sendpage,
+       .set_rcvlowat = vsock_set_rcvlowat,
 };
 
 static const struct proto_ops vsock_seqpacket_ops = {