Re: [PATCH net v5 3/3] selftests/bpf: Add mptcp test with sockmap

[Matthieu Baerts <matttbe@kernel.org>]

Hi Martin,

On 13/11/2025 22:48, Martin KaFai Lau wrote:
>> diff --git a/tools/testing/selftests/bpf/prog_tests/mptcp.c b/tools/
>> testing/selftests/bpf/prog_tests/mptcp.c
>> index f8eb7f9d4fd2..b976fe626343 100644
>> --- a/tools/testing/selftests/bpf/prog_tests/mptcp.c
>> +++ b/tools/testing/selftests/bpf/prog_tests/mptcp.c
>> @@ -6,11 +6,14 @@
>>   #include <netinet/in.h>
>>   #include <test_progs.h>
>>   #include <unistd.h>
>> +#include <error.h>
> 
> I changed to errno.h to be specific. I think you only need the values of
> an errno here.
>>   #include "cgroup_helpers.h"
>>   #include "network_helpers.h"
>> +#include "socket_helpers.h"
>>   #include "mptcp_sock.skel.h"
>>   #include "mptcpify.skel.h"
>>   #include "mptcp_subflow.skel.h"
>> +#include "mptcp_sockmap.skel.h"
>>     #define NS_TEST "mptcp_ns"
>>   #define ADDR_1    "10.0.1.1"
>> @@ -436,6 +439,142 @@ static void test_subflow(void)
>>       close(cgroup_fd);
>>   }
>>   +/* Test sockmap on MPTCP server handling non-mp-capable clients. */
>> +static void test_sockmap_with_mptcp_fallback(struct mptcp_sockmap *skel)
>> +{
>> +    int listen_fd = -1, client_fd1 = -1, client_fd2 = -1;
>> +    int server_fd1 = -1, server_fd2 = -1, sent, recvd;
>> +    char snd[9] = "123456789";
>> +    char rcv[10];
>> +
>> +    /* start server with MPTCP enabled */
>> +    listen_fd = start_mptcp_server(AF_INET, NULL, 0, 0);
>> +    if (!ASSERT_OK_FD(listen_fd, "sockmap-fb:start_mptcp_server"))
>> +        return;
>> +
>> +    skel->bss->trace_port = ntohs(get_socket_local_port(listen_fd));
>> +    skel->bss->sk_index = 0;
>> +    /* create client without MPTCP enabled */
>> +    client_fd1 = connect_to_fd_opts(listen_fd, NULL);
>> +    if (!ASSERT_OK_FD(client_fd1, "sockmap-fb:connect_to_fd"))
>> +        goto end;
>> +
>> +    server_fd1 = xaccept_nonblock(listen_fd, NULL, NULL);
>> +    skel->bss->sk_index = 1;
>> +    client_fd2 = connect_to_fd_opts(listen_fd, NULL);
>> +    if (!ASSERT_OK_FD(client_fd2, "sockmap-fb:connect_to_fd"))
>> +        goto end;
>> +
>> +    server_fd2 = xaccept_nonblock(listen_fd, NULL, NULL);
>> +    /* test normal redirect behavior: data sent by client_fd1 can be
>> +     * received by client_fd2
>> +     */
>> +    skel->bss->redirect_idx = 1;
>> +    sent = xsend(client_fd1, snd, sizeof(snd), 0);
>> +    if (!ASSERT_EQ(sent, sizeof(snd), "sockmap-fb:xsend(client_fd1)"))
>> +        goto end;
>> +
>> +    /* try to recv more bytes to avoid truncation check */
>> +    recvd = recv_timeout(client_fd2, rcv, sizeof(rcv), MSG_DONTWAIT, 2);
> 
> I removed the socket_helpers.h usage. The _nonblock, _timeout, and
> MSG_DONTWAIT are unnecessary. I replaced them with the regular accept,
> send, and recv. All fds from network_helpers.c have a default 3s
> timeout instead of 30s in xaccept_nonblock. This matches how most of
> the selftests/bpf are doing it as well.
> 
> I also touched up the commit message in patch 2 based on Matt's comment.

Thank you for having applied the patches, and for the modifications you did!

> Applied. Thanks.
> 
>> +    server_fd = xaccept_nonblock(listen_fd, NULL, NULL);
>> +    err = bpf_map_update_elem(bpf_map__fd(skel->maps.sock_map),
>> +                  &zero, &server_fd, BPF_NOEXIST);
> 

Cheers,
Matt
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