Re: [PATCH net-next v3 3/4] vsock: Move lingering logic to af_vsock core

[Stefano Garzarella <sgarzare@xxxxxxxxxx>]

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@xxxxxxxxxx>
> Signed-off-by: Michal Luczaj <mhal@xxxxxxx>
> ---
> 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