linux-kernel - Re: [PATCH net-next v4 3/3] vsock/test: Expand linger test to ensure close() does not misbehave

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Message-ID: <ff959c3e-4c47-4f93-8ab8-32446bb0e0d0@rbox.co>
Date: Wed, 7 May 2025 00:47:43 +0200
From: Michal Luczaj <mhal@...x.co>
To: Stefano Garzarella <sgarzare@...hat.com>
Cc: "David S. Miller" <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>,
 "Michael S. Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>,
 Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, Eugenio Pérez
 <eperezma@...hat.com>, Stefan Hajnoczi <stefanha@...hat.com>,
 virtualization@...ts.linux.dev, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH net-next v4 3/3] vsock/test: Expand linger test to ensure
 close() does not misbehave

On 5/6/25 11:46, Stefano Garzarella wrote:
> On Tue, 6 May 2025 at 11:43, Stefano Garzarella <sgarzare@...hat.com> wrote:
>>
>> On Thu, May 01, 2025 at 10:05:24AM +0200, Michal Luczaj wrote:
>>> There was an issue with SO_LINGER: instead of blocking until all queued
>>> messages for the socket have been successfully sent (or the linger timeout
>>> has been reached), close() would block until packets were handled by the
>>> peer.
>>
>> This is a new behaviour that only new kernels will follow, so I think
>> it is better to add a new test instead of extending a pre-existing test
>> that we described as "SOCK_STREAM SO_LINGER null-ptr-deref".
>>
>> The old test should continue to check the null-ptr-deref also for old
>> kernels, while the new test will check the new behaviour, so we can skip
>> the new test while testing an old kernel.

Right, I'll split it.

> I also saw that we don't have any test to verify that actually the
> lingering is working, should we add it since we are touching it?

Yeah, I agree we should. Do you have any suggestion how this could be done
reliably?

Thanks,
Michal