Re: [PATCH v2 bpf-next/net 6/6] selftest: bpf: Add test for sk->sk_bypass_prot_mem.

[Kuniyuki Iwashima <kuniyu@google.com>]

On Wed, Oct 15, 2025 at 12:07 PM Martin KaFai Lau <martin.lau@linux.dev> wrote:
>
> On 10/14/25 4:54 PM, Kuniyuki Iwashima wrote:
> > +static int tcp_create_sockets(struct test_case *test_case, int sk[], int len)
> > +{
> > +     int server, i, err = 0;
> > +
> > +     server = start_server(test_case->family, test_case->type, NULL, 0, 0);
> > +     if (!ASSERT_GE(server, 0, "start_server_str"))
> > +             return server;
> > +
> > +     /* Keep for-loop so we can change NR_SOCKETS easily. */
> > +     for (i = 0; i < len; i += 2) {
> > +             sk[i] = connect_to_fd(server, 0);
> > +             if (sk[i] < 0) {
> > +                     ASSERT_GE(sk[i], 0, "connect_to_fd");
> > +                     err = sk[i];
> > +                     break;
> > +             }
> > +
> > +             sk[i + 1] = accept(server, NULL, NULL);
> > +             if (sk[i + 1] < 0) {
> > +                     ASSERT_GE(sk[i + 1], 0, "accept");
> > +                     err = sk[i + 1];
> > +                     break;
> > +             }
> > +     }
> > +
> > +     close(server);
> > +
> > +     return err;
> > +}
> > +
>
> > +static int check_bypass(struct test_case *test_case,
> > +                     struct sk_bypass_prot_mem *skel, bool bypass)
> > +{
> > +     char buf[BUF_SINGLE] = {};
> > +     long memory_allocated[2];
> > +     int sk[NR_SOCKETS] = {};
> > +     int err, i, j;
> > +
> > +     err = test_case->create_sockets(test_case, sk, ARRAY_SIZE(sk));
> > +     if (err)
> > +             goto close;
> > +
> > +     memory_allocated[0] = test_case->get_memory_allocated(test_case, skel);
> > +
> > +     /* allocate pages >= NR_PAGES */
> > +     for (i = 0; i < ARRAY_SIZE(sk); i++) {
> > +             for (j = 0; j < NR_SEND; j++) {
> > +                     int bytes = send(sk[i], buf, sizeof(buf), 0);
> > +
> > +                     /* Avoid too noisy logs when something failed. */
> > +                     if (bytes != sizeof(buf)) {
> > +                             ASSERT_EQ(bytes, sizeof(buf), "send");
> > +                             if (bytes < 0) {
> > +                                     err = bytes;
> > +                                     goto drain;
> > +                             }
> > +                     }
> > +             }
> > +     }
> > +
> > +     memory_allocated[1] = test_case->get_memory_allocated(test_case, skel);
> > +
> > +     if (bypass)
> > +             ASSERT_LE(memory_allocated[1], memory_allocated[0] + 10, "bypass");
> > +     else
> > +             ASSERT_GT(memory_allocated[1], memory_allocated[0] + NR_PAGES, "no bypass");
> > +
> > +drain:
> > +     if (test_case->type == SOCK_DGRAM) {
> > +             /* UDP starts purging sk->sk_receive_queue after one RCU
> > +              * grace period, then udp_memory_allocated goes down,
> > +              * so drain the queue before close().
> > +              */
> > +             for (i = 0; i < ARRAY_SIZE(sk); i++) {
> > +                     for (j = 0; j < NR_SEND; j++) {
> > +                             int bytes = recv(sk[i], buf, 1, MSG_DONTWAIT | MSG_TRUNC);
> > +
> > +                             if (bytes == sizeof(buf))
> > +                                     continue;
> > +                             if (bytes != -1 || errno != EAGAIN)
> > +                                     PRINT_FAIL("bytes: %d, errno: %s\n", bytes, strerror(errno));
> > +                             break;
> > +                     }
> > +             }
> > +     }
> > +
> > +close:
> > +     for (i = 0; i < ARRAY_SIZE(sk); i++) {
> > +             if (sk[i] <= 0)
>
> Theoretically, 0 is a legit fd. The tcp_create_sockets above is also testing
> ASSERT_GE(sk[i], 0, ...). I changed to test "< 0" here and initialize all sk[]
> to -1 at the beginning of this function.
>
> > +                     break;
> > +
> > +             close(sk[i]);
> > +     }
> > +
> > +     return err;
> > +}
> > +
>
>
> > +struct test_case test_cases[] = {
>
> Added static.
>
> Applied. Thanks.

Thank you for fixups, Martin !