linux-kernel - Re: [PATCH net-next v3 3/4] vsock: Move lingering logic to af

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Message-ID: <kz3s5mu7bc5kqb22g6voacrinda3wszwhlda7nnwhm5bciweuc@dpsyq2yfrs7f>
Date: Wed, 30 Apr 2025 11:33:30 +0200
From: Stefano Garzarella <sgarzare@...hat.com>
To: Michal Luczaj <mhal@...x.co>
Cc: "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>, virtualization@...ts.linux.dev, netdev@...r.kernel.org, 
	linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH net-next v3 3/4] vsock: Move lingering logic to af_vsock
 core

On Wed, Apr 30, 2025 at 11:10:29AM +0200, Michal Luczaj wrote:
>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.
>
>Guard against an unimplemented vsock_transport::unsent_bytes() callback.
>
>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                | 25 +++++++++++++++++++++++++
> net/vmw_vsock/virtio_transport_common.c | 23 +----------------------
> 3 files changed, 27 insertions(+), 22 deletions(-)
>
>diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
>index 9e85424c834353d016a527070dd62e15ff3bfce1..bd8b88d70423051dd05fc445fe37971af631ba03 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, long timeout);
>
> /**** TAP ****/
>
>diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>index fc6afbc8d6806a4d98c66abc3af4bd139c583b08..946b37de679a0e68b84cd982a3af2a959c60ee57 100644
>--- a/net/vmw_vsock/af_vsock.c
>+++ b/net/vmw_vsock/af_vsock.c
>@@ -1013,6 +1013,31 @@ static int vsock_getname(struct socket *sock,
> 	return err;
> }
>
>+void vsock_linger(struct sock *sk, long timeout)
>+{
>+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
>+	ssize_t (*unsent)(struct vsock_sock *vsk);
>+	struct vsock_sock *vsk = vsock_sk(sk);
>+
>+	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 4425802c5d718f65aaea425ea35886ad64e2fe6e..9230b8358ef2ac1f6e72a5961bae39f9093c8884 100644
>--- a/net/vmw_vsock/virtio_transport_common.c
>+++ b/net/vmw_vsock/virtio_transport_common.c
>@@ -1192,27 +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)
>-{
>-	DEFINE_WAIT_FUNC(wait, woken_wake_function);
>-	ssize_t (*unsent)(struct vsock_sock *vsk);
>-	struct vsock_sock *vsk = vsock_sk(sk);
>-
>-	if (!timeout)
>-		return;
>-
>-	unsent = vsk->transport->unsent_bytes;
>-
>-	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);
>-}
>-
> static void virtio_transport_cancel_close_work(struct vsock_sock *vsk,
> 					       bool cancel_timeout)
> {
>@@ -1283,7 +1262,7 @@ static bool virtio_transport_close(struct vsock_sock *vsk)
> 		(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);
>+		vsock_linger(sk, sk->sk_lingertime);

What about removing the `sk->sk_lingertime` parameter here?
vsock_linger() can get it from sk.

BTW, the change LGTM, would be great to call vsock_linger() directly in 
__vsock_release(), but we can do it later.

Thanks,
Stefano

>
> 	if (sock_flag(sk, SOCK_DONE)) {
> 		return true;
>
>-- 
>2.49.0
>
>