Re: [PATCH bpf-next 3/3] selftests/bpf: use start_server_str rather than start_reuseport_server in tc_tunnel

[Martin KaFai Lau]

On 10/31/25 2:01 AM, Alexis Lothoré (eBPF Foundation) wrote:
test_tc_tunnel currently uses start_reuseport_server because it needs to
frequently start and stop the server, so we need SO_REUSEPORT to avoid
getting errors on server restart due to the socket being in TIME_WAIT
state. But the test is only using one server at a time, so it is a bit
confusing to use this API.

Replace start_reuseport with start_sever_str, and provided the relevant
callback to set SO_REUSEPORT.

Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.loth...@bootlin.com>
---
  .../selftests/bpf/prog_tests/test_tc_tunnel.c      | 24 +++++++++++++++-------
  1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/test_tc_tunnel.c 
b/tools/testing/selftests/bpf/prog_tests/test_tc_tunnel.c
index deea90aaefad..8e3fe6dc6221 100644
--- a/tools/testing/selftests/bpf/prog_tests/test_tc_tunnel.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_tc_tunnel.c
@@ -69,7 +69,7 @@ struct subtest_cfg {
        int client_egress_prog_fd;
        int server_ingress_prog_fd;
        char extra_decap_mod_args[TUNNEL_ARGS_MAX_LEN];
-       int *server_fd;
+       int server_fd;
  };
  
  struct connection {
@@ -131,20 +131,30 @@ static void set_subtest_addresses(struct subtest_cfg *cfg)
        }
  }
  
+static int reuseport_cb(int fd, void *opts)
+{
+       int one = 1;
+
+       return setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one));
+}
+
  static int run_server(struct subtest_cfg *cfg)
  {
        int family = cfg->ipproto == 6 ? AF_INET6 : AF_INET;
+       struct network_helper_opts opts = {
+               .timeout_ms = TIMEOUT_MS,
+               .post_socket_cb = reuseport_cb,
+       };
        struct nstoken *nstoken;
  
  	nstoken = open_netns(SERVER_NS);
        if (!ASSERT_OK_PTR(nstoken, "open server ns"))
                return -1;
  
-	cfg->server_fd = start_reuseport_server(family, SOCK_STREAM,
-                                               cfg->server_addr, TEST_PORT,
-                                               TIMEOUT_MS, 1);
+       cfg->server_fd = start_server_str(family, SOCK_STREAM, cfg->server_addr,
+                                         TEST_PORT, &opts);

I meant to directly enable SO_REUSE"ADDR" in the start_server_addr()
instead of each individual test using SO_REUSEPORT. I think all tcp server
in test_progs should have it enabled. Something like this:

diff --git a/tools/testing/selftests/bpf/network_helpers.c 
b/tools/testing/selftests/bpf/network_helpers.c
index 8bb09167399a..e8b33d902bbc 100644
--- a/tools/testing/selftests/bpf/network_helpers.c
+++ b/tools/testing/selftests/bpf/network_helpers.c
@@ -97,7 +97,7 @@ int settimeo(int fd, int timeout_ms)
 int start_server_addr(int type, const struct sockaddr_storage *addr, socklen_t 
addrlen,
                      const struct network_helper_opts *opts)
 {
-       int fd;
+       int fd, on = 1;
 
 	if (!opts)
                opts = &default_opts;
@@ -111,6 +111,12 @@ int start_server_addr(int type, const struct 
sockaddr_storage *addr, socklen_t a
        if (settimeo(fd, opts->timeout_ms))
                goto error_close;
 
+	if (type == SOCK_STREAM &&
+           setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on))) {
+               log_err("Failed to enable SO_REUSEADDR");
+               goto error_close;
+       }
+
        if (opts->post_socket_cb &&
            opts->post_socket_cb(fd, opts->cb_opts)) {
                log_err("Failed to call post_socket_cb");


I have applied patch 1 and 2.