linux-kernel - Re: [PATCH net 2/2] vsock/test: Test setting SO

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Message-ID: <aUrIDT-Tg5SpXhlO@sgarzare-redhat>
Date: Tue, 23 Dec 2025 17:50:45 +0100
From: Stefano Garzarella <sgarzare@...hat.com>
To: Michal Luczaj <mhal@...x.co>
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>, 
	Arseniy Krasnov <avkrasnov@...utedevices.com>, virtualization@...ts.linux.dev, netdev@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH net 2/2] vsock/test: Test setting SO_ZEROCOPY on
 accept()ed socket

On Tue, Dec 23, 2025 at 02:20:33PM +0100, Stefano Garzarella wrote:
>On Tue, Dec 23, 2025 at 12:10:25PM +0100, Michal Luczaj wrote:
>>On 12/23/25 11:27, Stefano Garzarella wrote:
>>>On Tue, Dec 23, 2025 at 10:15:29AM +0100, Michal Luczaj wrote:
>>>>Make sure setsockopt(SOL_SOCKET, SO_ZEROCOPY) on an accept()ed socket is
>>>>handled by vsock's implementation.
>>>>
>>>>Signed-off-by: Michal Luczaj <mhal@...x.co>
>>>>---
>>>>tools/testing/vsock/vsock_test.c | 33 +++++++++++++++++++++++++++++++++
>>>>1 file changed, 33 insertions(+)
>>>>
>>>>diff --git a/tools/testing/vsock/vsock_test.c b/tools/testing/vsock/vsock_test.c
>>>>index 9e1250790f33..8ec8f0844e22 100644
>>>>--- a/tools/testing/vsock/vsock_test.c
>>>>+++ b/tools/testing/vsock/vsock_test.c
>>>>@@ -2192,6 +2192,34 @@ static void test_stream_nolinger_server(const struct test_opts *opts)
>>>>	close(fd);
>>>>}
>>>>
>>>>+static void test_stream_accepted_setsockopt_client(const struct test_opts *opts)
>>>>+{
>>>>+	int fd;
>>>>+
>>>>+	fd = vsock_stream_connect(opts->peer_cid, opts->peer_port);
>>>>+	if (fd < 0) {
>>>>+		perror("connect");
>>>>+		exit(EXIT_FAILURE);
>>>>+	}
>>>>+
>>>>+	vsock_wait_remote_close(fd);

On a second look, why we need to wait the remote close?
can we just have a control message?

I'm not sure even on that, I mean why this peer can't close the
connection while the other is checking if it's able to set zerocopy?


>>>>+	close(fd);
>>>>+}
>>>>+
>>>>+static void test_stream_accepted_setsockopt_server(const struct test_opts *opts)
>>>>+{
>>>>+	int fd;
>>>>+
>>>>+	fd = vsock_stream_accept(VMADDR_CID_ANY, opts->peer_port, NULL);
>>>>+	if (fd < 0) {
>>>>+		perror("accept");
>>>>+		exit(EXIT_FAILURE);
>>>>+	}
>>>>+
>>>>+	enable_so_zerocopy_check(fd);
>>>
>>>This test is passing on my env also without the patch applied.
>>>
>>>Is that expected?
>>
>>Oh, no, definitely not. It fails for me:
>>36 - SOCK_STREAM accept()ed socket custom setsockopt()...36 - SOCK_STREAM
>>accept()ed socket custom setsockopt()...setsockopt err: Operation not
>>supported (95)
>>setsockopt SO_ZEROCOPY val 1
>
>aaa, right, the server is failing, sorry ;-)
>
>Reviewed-by: Stefano Garzarella <sgarzare@...hat.com>
>>
>>I have no idea what's going on :)
>>
>
>In my suite, I'm checking the client, and if the last test fails only 
>on the server, I'm missing it. I'd fix my suite, and maybe also 
>vsock_test adding another sync point.

Added a full barrier here: 
https://lore.kernel.org/netdev/20251223162210.43976-1-sgarzare@redhat.com

Thanks,
Stefano