[PATCH net-next v4 1/9] vsock: SO_RCVLOWAT transport set callback

Arseniy Krasnov
2022-08-19T05:25:55Z

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>
---
include/net/af_vsock.h | 1 +
net/vmw_vsock/af_vsock.c | 20 ++++++++++++++++++++
2 files changed, 21 insertions(+)

diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index 1c53c4c4d88f..d609a088cb27 100644
--- 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 f04abf662ec6..0a6777526c73 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -2129,6 +2129,25 @@ vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
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,
@@ -2148,6 +2167,7 @@ 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 = {
--
2.25.1