2023-07-01 06:55:33

by Arseniy Krasnov

Subject: [RFC PATCH v5 06/17] vsock: fix EPOLLERR set on non-empty error queue

If socket's error queue is not empty, EPOLLERR must be set. Otherwise,
reader of error queue won't detect data in it using EPOLLERR bit.
Currently for AF_VSOCK this is reproducible only with MSG_ZEROCOPY, as
this feature is the only user of an error queue of the socket.

Fixes: d021c344051a ("VSOCK: Introduce VM Sockets")
Signed-off-by: Arseniy Krasnov <[email protected]>
---
Changelog:
v4 -> v5:
* Change commit message as Fix patch. Also add details that this
problem could be reproduced only with MSG_ZEROCOPY transmission
mode.

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 efb8a0937a13..45fd20c4ed50 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1030,7 +1030,7 @@ 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

2023-07-06 17:10:20

by Stefano Garzarella

Subject: Re: [RFC PATCH v5 06/17] vsock: fix EPOLLERR set on non-empty error queue

On Sat, Jul 01, 2023 at 09:39:36AM +0300, Arseniy Krasnov wrote:
>If socket's error queue is not empty, EPOLLERR must be set. Otherwise,
>reader of error queue won't detect data in it using EPOLLERR bit.
>Currently for AF_VSOCK this is reproducible only with MSG_ZEROCOPY, as
>this feature is the only user of an error queue of the socket.
>
>Fixes: d021c344051a ("VSOCK: Introduce VM Sockets")

Sorry if I confused you, but if without MSG_ZEROCOPY this is not an
issue, then we can remove the Fixes tag.

>Signed-off-by: Arseniy Krasnov <[email protected]>
>---
> Changelog:
> v4 -> v5:
> * Change commit message as Fix patch. Also add details that this
> problem could be reproduced only with MSG_ZEROCOPY transmission
> mode.
>
> 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 efb8a0937a13..45fd20c4ed50 100644
>--- a/net/vmw_vsock/af_vsock.c
>+++ b/net/vmw_vsock/af_vsock.c
>@@ -1030,7 +1030,7 @@ 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
>