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

Stefano Garzarella
Thu, 02 Mar 2023 10:06:21 -0000

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 at sberdevices.ru>
>---
> 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
>