[v4] vsock: MSG_ZEROCOPY flag support

[RFC PATCH v4 06/17] vsock: check error queue to set EPOLLERR

Posted by Arseniy Krasnov 2 years, 8 months ago

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.

Signed-off-by: Arseniy Krasnov <AVKrasnov@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 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

Re: [RFC PATCH v4 06/17] vsock: check error queue to set EPOLLERR

Posted by Stefano Garzarella 2 years, 7 months ago

On Sat, Jun 03, 2023 at 11:49:28PM +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.
>
>Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
>---
> net/vmw_vsock/af_vsock.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

This patch looks like it can go even without this series.

Is it a fix? Should we add a fixes tag?

Thanks,
Stefano

>
>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
>

Re: [RFC PATCH v4 06/17] vsock: check error queue to set EPOLLERR

Posted by Arseniy Krasnov 2 years, 7 months ago


On 26.06.2023 19:04, Stefano Garzarella wrote:
> On Sat, Jun 03, 2023 at 11:49:28PM +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.
>>
>> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
>> ---
>> net/vmw_vsock/af_vsock.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> This patch looks like it can go even without this series.
> 
> Is it a fix? Should we add a fixes tag?

Yes, it is fix and I can exclude it from this set to reduce number
of patches, but there is no reproducer for this without MSG_ZEROCOPY
support - at this moment this feature is the only user of error queue
for AF_VSOCK.

Thanks, Arseniy

> 
> Thanks,
> Stefano
> 
>>
>> 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
>>
>

Re: [RFC PATCH v4 06/17] vsock: check error queue to set EPOLLERR

Posted by Stefano Garzarella 2 years, 7 months ago

On Tue, Jun 27, 2023 at 07:44:25AM +0300, Arseniy Krasnov wrote:
>
>
>On 26.06.2023 19:04, Stefano Garzarella wrote:
>> On Sat, Jun 03, 2023 at 11:49:28PM +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.
>>>
>>> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
>>> ---
>>> net/vmw_vsock/af_vsock.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> This patch looks like it can go even without this series.
>>
>> Is it a fix? Should we add a fixes tag?
>
>Yes, it is fix and I can exclude it from this set to reduce number
>of patches, but there is no reproducer for this without MSG_ZEROCOPY
>support - at this moment this feature is the only user of error queue
>for AF_VSOCK.

Okay, so it's fine to keep it here, but please mention in the comment 
that without MSG_ZEROCOPY it can't be reproduced.

That way we know that we don't have to backport into the stable 
branches.

Thanks,
Stefano

>
>Thanks, Arseniy
>
>>
>> Thanks,
>> Stefano
>>
>>>
>>> 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
>>>
>>
>