Re: [RFC PATCH v1] vsock: check error queue to set EPOLLERR

[Stefano Garzarella]

On Wed, Mar 01, 2023 at 08:19:45AM +0300, Arseniy Krasnov wrote:
> EPOLLERR must be set not only when there is error on the socket, but also
> when error queue of it is not empty (may be it contains some control
> messages). Without this patch 'poll()' won't detect data in error queue.

Do you have a reproducer?

> This patch is based on 'tcp_poll()'.

LGTM but we should add a Fixes tag.
It's not clear to me whether the problem depends on when we switched to 
using sk_buff or was pre-existing.

Do you have any idea when we introduced this issue?

Thanks,
Stefano

> Signed-off-by: Arseniy Krasnov <AVKrasnov@xxxxxxxxxxxxxx>
> ---
> net/vmw_vsock/af_vsock.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> index 19aea7cba26e..b5e51ef4a74c 100644
> --- a/net/vmw_vsock/af_vsock.c
> +++ b/net/vmw_vsock/af_vsock.c
> @@ -1026,7 +1026,7 @@ static __poll_t vsock_poll(struct file *file, struct socket *sock,
> 	poll_wait(file, sk_sleep(sk), wait);
> 	mask = 0;
>
> -	if (sk->sk_err)
> +	if (sk->sk_err || !skb_queue_empty_lockless(&sk->sk_error_queue))
> 		/* Signify that there has been an error on this socket. */
> 		mask |= EPOLLERR;
>
> --
> 2.25.1