Re: [PATCH net] vsock: Ignore signal/timeout on connect() if already established

[Michal Luczaj <mhal@rbox.co>]

On 11/18/25 10:51, Stefano Garzarella wrote:
> On Mon, Nov 17, 2025 at 09:57:25PM +0100, Michal Luczaj wrote:
>> ...
>> +static void vsock_reset_interrupted(struct sock *sk)
>> +{
>> +	struct vsock_sock *vsk = vsock_sk(sk);
>> +
>> +	/* Try to cancel VIRTIO_VSOCK_OP_REQUEST skb sent out by
>> +	 * transport->connect().
>> +	 */
>> +	vsock_transport_cancel_pkt(vsk);
>> +
>> +	/* Listener might have already responded with VIRTIO_VSOCK_OP_RESPONSE.
>> +	 * Its handling expects our sk_state == TCP_SYN_SENT, which hereby we
>> +	 * break. In such case VIRTIO_VSOCK_OP_RST will follow.
>> +	 */
>> +	sk->sk_state = TCP_CLOSE;
>> +	sk->sk_socket->state = SS_UNCONNECTED;
>> +}
>> +
>> static int vsock_connect(struct socket *sock, struct sockaddr *addr,
>> 			 int addr_len, int flags)
>> {
>> @@ -1661,18 +1678,33 @@ static int vsock_connect(struct socket *sock, struct sockaddr *addr,
>> 		timeout = schedule_timeout(timeout);
>> 		lock_sock(sk);
>>
>> +		/* Connection established. Whatever happens to socket once we
>> +		 * release it, that's not connect()'s concern. No need to go
>> +		 * into signal and timeout handling. Call it a day.
>> +		 *
>> +		 * Note that allowing to "reset" an already established socket
>> +		 * here is racy and insecure.
>> +		 */
>> +		if (sk->sk_state == TCP_ESTABLISHED)
>> +			break;
>> +
>> +		/* If connection was _not_ established and a signal/timeout came
>> +		 * to be, we want the socket's state reset. User space may want
>> +		 * to retry.
>> +		 *
>> +		 * sk_state != TCP_ESTABLISHED implies that socket is not on
>> +		 * vsock_connected_table. We keep the binding and the transport
>> +		 * assigned.
>> +		 */
>> 		if (signal_pending(current)) {
>> 			err = sock_intr_errno(timeout);
>> -			sk->sk_state = sk->sk_state == TCP_ESTABLISHED ? TCP_CLOSING : TCP_CLOSE;
>> -			sock->state = SS_UNCONNECTED;
>> -			vsock_transport_cancel_pkt(vsk);
>> -			vsock_remove_connected(vsk);
>> +			vsock_reset_interrupted(sk);
>> 			goto out_wait;
>> -		} else if ((sk->sk_state != TCP_ESTABLISHED) && (timeout == 0)) {
>> +		}
>> +
>> +		if (timeout == 0) {
>> 			err = -ETIMEDOUT;
>> -			sk->sk_state = TCP_CLOSE;
>> -			sock->state = SS_UNCONNECTED;
>> -			vsock_transport_cancel_pkt(vsk);
>> +			vsock_reset_interrupted(sk);
>> 			goto out_wait;
> 
> I'm fine with the change, but now both code blocks are the same, so
> can we unify them?
> I mean something like this:
> 		if (signal_pending(current) || timeout == 0 {
> 			err = timeout == 0 ? -ETIMEDOUT : sock_intr_errno(timeout);
> 			...
> 		}
> 
> Maybe at that point we can also remove the vsock_reset_interrupted()
> function and put the code right there.
> 
> BTW I don't have a strong opinion, what do you prefer?

Sure, no problem.

But I've realized invoking `sock_intr_errno(timeout)` is unnecessary.
`timeout` can't be MAX_SCHEDULE_TIMEOUT, so the call always evaluates to
-EINTR, right?