netdev - [PATCH net-next v4 2/3] vsock: Move lingering logic to af

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Message-Id: <20250501-vsock-linger-v4-2-beabbd8a0847@rbox.co>
Date: Thu, 01 May 2025 10:05:23 +0200
From: Michal Luczaj <mhal@...x.co>
To: Stefano Garzarella <sgarzare@...hat.com>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Simon Horman <horms@...nel.org>, "Michael S. Tsirkin" <mst@...hat.com>, 
 Jason Wang <jasowang@...hat.com>, Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, 
 Eugenio Pérez <eperezma@...hat.com>, 
 Stefan Hajnoczi <stefanha@...hat.com>
Cc: virtualization@...ts.linux.dev, netdev@...r.kernel.org, 
 linux-kernel@...r.kernel.org, kvm@...r.kernel.org, 
 Michal Luczaj <mhal@...x.co>
Subject: [PATCH net-next v4 2/3] vsock: Move lingering logic to af_vsock
 core

Lingering should be transport-independent in the long run. In preparation
for supporting other transports, as well the linger on shutdown(), move
code to core.

Generalize by querying vsock_transport::unsent_bytes(), guard against the
callback being unimplemented. Do not pass sk_lingertime explicitly. Pull
SOCK_LINGER check into vsock_linger().

Flatten the function. Remove the nested block by inverting the condition:
return early on !timeout.

Suggested-by: Stefano Garzarella <sgarzare@...hat.com>
Signed-off-by: Michal Luczaj <mhal@...x.co>
---
 include/net/af_vsock.h                  |  1 +
 net/vmw_vsock/af_vsock.c                | 30 ++++++++++++++++++++++++++++++
 net/vmw_vsock/virtio_transport_common.c | 23 ++---------------------
 3 files changed, 33 insertions(+), 21 deletions(-)

diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index 9e85424c834353d016a527070dd62e15ff3bfce1..d56e6e135158939087d060dfcf65d3fdaea53bf3 100644
--- a/include/net/af_vsock.h
+++ b/include/net/af_vsock.h
@@ -221,6 +221,7 @@ void vsock_for_each_connected_socket(struct vsock_transport *transport,
 				     void (*fn)(struct sock *sk));
 int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk);
 bool vsock_find_cid(unsigned int cid);
+void vsock_linger(struct sock *sk);
 
 /**** TAP ****/
 
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index fc6afbc8d6806a4d98c66abc3af4bd139c583b08..a31ad6b141cd38d1806df4b5d417924bb8607e32 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1013,6 +1013,36 @@ static int vsock_getname(struct socket *sock,
 	return err;
 }
 
+void vsock_linger(struct sock *sk)
+{
+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
+	ssize_t (*unsent)(struct vsock_sock *vsk);
+	struct vsock_sock *vsk = vsock_sk(sk);
+	long timeout;
+
+	if (!sock_flag(sk, SOCK_LINGER))
+		return;
+
+	timeout = sk->sk_lingertime;
+	if (!timeout)
+		return;
+
+	/* unsent_bytes() may be unimplemented. */
+	unsent = vsk->transport->unsent_bytes;
+	if (!unsent)
+		return;
+
+	add_wait_queue(sk_sleep(sk), &wait);
+
+	do {
+		if (sk_wait_event(sk, &timeout, unsent(vsk) == 0, &wait))
+			break;
+	} while (!signal_pending(current) && timeout);
+
+	remove_wait_queue(sk_sleep(sk), &wait);
+}
+EXPORT_SYMBOL_GPL(vsock_linger);
+
 static int vsock_shutdown(struct socket *sock, int mode)
 {
 	int err;
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index 045ac53f69735e1979162aea8c9ab5961407640c..aa308f285bf1bcf4c689407033de854c6f85a639 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -1192,25 +1192,6 @@ static void virtio_transport_remove_sock(struct vsock_sock *vsk)
 	vsock_remove_sock(vsk);
 }
 
-static void virtio_transport_wait_close(struct sock *sk, long timeout)
-{
-	if (timeout) {
-		DEFINE_WAIT_FUNC(wait, woken_wake_function);
-		struct vsock_sock *vsk = vsock_sk(sk);
-
-		add_wait_queue(sk_sleep(sk), &wait);
-
-		do {
-			if (sk_wait_event(sk, &timeout,
-					  virtio_transport_unsent_bytes(vsk) == 0,
-					  &wait))
-				break;
-		} while (!signal_pending(current) && timeout);
-
-		remove_wait_queue(sk_sleep(sk), &wait);
-	}
-}
-
 static void virtio_transport_cancel_close_work(struct vsock_sock *vsk,
 					       bool cancel_timeout)
 {
@@ -1280,8 +1261,8 @@ static bool virtio_transport_close(struct vsock_sock *vsk)
 	if ((sk->sk_shutdown & SHUTDOWN_MASK) != SHUTDOWN_MASK)
 		(void)virtio_transport_shutdown(vsk, SHUTDOWN_MASK);
 
-	if (sock_flag(sk, SOCK_LINGER) && !(current->flags & PF_EXITING))
-		virtio_transport_wait_close(sk, sk->sk_lingertime);
+	if (!(current->flags & PF_EXITING))
+		vsock_linger(sk);
 
 	if (sock_flag(sk, SOCK_DONE)) {
 		return true;

-- 
2.49.0