Re: [PATCH net-next v4 3/3] vsock/test: Expand linger test to ensure close() does not misbehave
From: Stefano Garzarella <sgarzare@redhat.com>
Date: 2025-05-20 09:01:52
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kvm, lkml, virtualization
On Tue, 20 May 2025 at 10:54, Stefano Garzarella [off-list ref] wrote:
On Mon, May 12, 2025 at 02:23:12PM +0200, Michal Luczaj wrote:quoted
On 5/7/25 10:26, Stefano Garzarella wrote:quoted
On Wed, 7 May 2025 at 00:47, Michal Luczaj [off-list ref] wrote:quoted
On 5/6/25 11:46, Stefano Garzarella wrote:quoted
On Tue, 6 May 2025 at 11:43, Stefano Garzarella [off-list ref] wrote:quoted
On Thu, May 01, 2025 at 10:05:24AM +0200, Michal Luczaj wrote:quoted
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.quoted
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?Can we play with SO_VM_SOCKETS_BUFFER_SIZE like in credit-update tests? One peer can set it (e.g. to 1k), accept the connection, but without read anything. The other peer can set the linger timeout, send more bytes than the buffer size set by the receiver. At this point the extra bytes should stay on the sender socket buffer, so we can do the close() and it should time out, and we can check if it happens. WDYT?Haven't we discussed this approach in [1]? I've reported that I can't makeSorry, I forgot. What was the conclusion? Why this can't work?quoted
it work. But maybe I'm misunderstanding something, please see the code below.What I should check in the code below?
Okay, I see the send() is blocking (please next time explain better the issue, etc.) I don't want to block this series, so feel free to investigate that later if we have a way to test it. If I'll find some time, I'll try to check if we have a way. Thanks, Stefano