Re: [RFC PATCH v3 5/9] vsock: pass sock_rcvlowat to notify_poll_in as target

[Stefano Garzarella]

On Wed, Aug 03, 2022 at 01:59:49PM +0000, Arseniy Krasnov wrote:
> This callback controls setting of POLLIN,POLLRDNORM output bits of poll()
> syscall,but in some cases,it is incorrectly to set it, when socket has
> at least 1 bytes of available data.

I suggest you refrase the description a bit, which should describe what 
was the problem and what the patch does, so I was thinking something 
like this:

  Passing 1 as the target to notify_poll_in(), we don't honor
  what the user has set via SO_RCVLOWAT, going to set POLLIN
  and POLLRDNORM, even if we don't have the amount of bytes
  expected by the user.

  Let's use sock_rcvlowat() to get the right target to pass to
  notify_poll_in().

Anyway, the patch LGTM:

Reviewed-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>

> Signed-off-by: Arseniy Krasnov <AVKrasnov@xxxxxxxxxxxxxx>
> ---
> net/vmw_vsock/af_vsock.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> index 016ad5ff78b7..3a1426eb8baa 100644
> --- a/net/vmw_vsock/af_vsock.c
> +++ b/net/vmw_vsock/af_vsock.c
> @@ -1066,8 +1066,9 @@ static __poll_t vsock_poll(struct file *file, struct socket *sock,
> 		if (transport && transport->stream_is_active(vsk) &&
> 		    !(sk->sk_shutdown & RCV_SHUTDOWN)) {
> 			bool data_ready_now = false;
> +			int target = sock_rcvlowat(sk, 0, INT_MAX);
> 			int ret = transport->notify_poll_in(
> -					vsk, 1, &data_ready_now);
> +					vsk, target, &data_ready_now);
> 			if (ret < 0) {
> 				mask |= EPOLLERR;
> 			} else {
> --
> 2.25.1