Re: [PATCH net-next v3 1/4] vsock/virtio: Linger on unsent data

[Michal Luczaj <mhal@rbox.co>]

On 4/30/25 11:26, Stefano Garzarella wrote:
> On Wed, Apr 30, 2025 at 11:10:27AM +0200, Michal Luczaj wrote:
>> Currently vsock's lingering effectively boils down to waiting (or timing
>> out) until packets are consumed or dropped by the peer; be it by receiving
>> the data, closing or shutting down the connection.
>>
>> To align with the semantics described in the SO_LINGER section of man
>> socket(7) and to mimic AF_INET's behaviour more closely, change the logic
>> of a lingering close(): instead of waiting for all data to be handled,
>> block until data is considered sent from the vsock's transport point of
>> view. That is until worker picks the packets for processing and decrements
>> virtio_vsock_sock::bytes_unsent down to 0.
>>
>> Note that (some interpretation of) lingering was always limited to
>> transports that called virtio_transport_wait_close() on transport release.
>> This does not change, i.e. under Hyper-V and VMCI no lingering would be
>> observed.
>>
>> The implementation does not adhere strictly to man page's interpretation of
>> SO_LINGER: shutdown() will not trigger the lingering. This follows AF_INET.
>>
>> Signed-off-by: Michal Luczaj <mhal@rbox.co>
>> ---
>> net/vmw_vsock/virtio_transport_common.c | 8 ++++++--
>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
>> index 7f7de6d8809655fe522749fbbc9025df71f071bd..49c6617b467195ba385cc3db86caa4321b422d7a 100644
>> --- a/net/vmw_vsock/virtio_transport_common.c
>> +++ b/net/vmw_vsock/virtio_transport_common.c
>> @@ -1196,12 +1196,16 @@ static void virtio_transport_wait_close(struct sock *sk, long timeout)
>> {
>> 	if (timeout) {
>> 		DEFINE_WAIT_FUNC(wait, woken_wake_function);
>> +		ssize_t (*unsent)(struct vsock_sock *vsk);
>> +		struct vsock_sock *vsk = vsock_sk(sk);
>> +
>> +		unsent = vsk->transport->unsent_bytes;
> 
> Just use `virtio_transport_unsent_bytes`, we don't need to be generic on 
> transport here.

All right.

Thanks