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

From: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
To: Stefano Garzarella <sgarzare@redhat.com>,
	"David S. Miller" <davem@davemloft.net>,
	"edumazet@google.com" <edumazet@google.com>,
	"Jakub Kicinski" <kuba@kernel.org>,
	Paolo Abeni <pabeni@redhat.com>,
	"kys@microsoft.com" <kys@microsoft.com>,
	"haiyangz@microsoft.com" <haiyangz@microsoft.com>,
	"sthemmin@microsoft.com" <sthemmin@microsoft.com>,
	"wei.liu@kernel.org" <wei.liu@kernel.org>,
	Dexuan Cui <decui@microsoft.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	Bryan Tan <bryantan@vmware.com>, Vishnu Dasa <vdasa@vmware.com>,
	Krasnov Arseniy <oxffffaa@gmail.com>,
	"Michael S. Tsirkin" <mst@redhat.com>
Cc: "virtualization@lists.linux-foundation.org" 
	<virtualization@lists.linux-foundation.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	kernel <kernel@sberdevices.ru>,
	VMware PV-Drivers Reviewers <pv-drivers@vmware.com>
Subject: [PATCH net-next v4 1/9] vsock: SO_RCVLOWAT transport set callback
Date: Fri, 19 Aug 2022 05:25:19 +0000	[thread overview]
Message-ID: <09389925-8a2f-24c8-6975-f84822b12fe8@sberdevices.ru> (raw)
In-Reply-To: <de41de4c-0345-34d7-7c36-4345258b7ba8@sberdevices.ru>

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
