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

[Stefano Garzarella]

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 <sgarz...@redhat.com>
Signed-off-by: Michal Luczaj <m...@rbox.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);

Ah, I'd also move the check in that function, I mean:

void vsock_linger(struct sock *sk) {
        ...
        if (!sock_flag(sk, SOCK_LINGER) || (current->flags & PF_EXITING))
                return;

        ...
}

Or, if we move the call to vsock_linger() in __vsock_release(), we can
do the check there.

Thanks,
Stefano

        if (sock_flag(sk, SOCK_DONE)) {
                return true;

--
2.49.0