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selftests/bpf: test_progs: fix client/server race in tcp_rtt

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This is the same problem I found earlier in test_sockopt_inherit:
there is a race between server thread doing accept() and client
thread doing connect(). Let's explicitly synchronize them via
pthread conditional variable.

v2:
* don't exit from server_thread without signaling condvar,
  fixes possible issue where main() would wait forever (Andrii Nakryiko)

Fixes: b55873984d ("selftests/bpf: test BPF_SOCK_OPS_RTT_CB")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Stanislav Fomichev 2019-09-23 11:41:12 -07:00 committed by Daniel Borkmann
parent 733ef7f056
commit 8a03222f50
1 changed files with 19 additions and 2 deletions
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21
tools/testing/selftests/bpf/prog_tests/tcp_rtt.c
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@ -203,14 +203,24 @@ static int start_server(void)
return fd;
}
static pthread_mutex_t server_started_mtx = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t server_started = PTHREAD_COND_INITIALIZER;
static void *server_thread(void *arg)
{
struct sockaddr_storage addr;
socklen_t len = sizeof(addr);
int fd = *(int *)arg;
int client_fd;
int err;
if (CHECK_FAIL(listen(fd, 1)) < 0) {
err = listen(fd, 1);
pthread_mutex_lock(&server_started_mtx);
pthread_cond_signal(&server_started);
pthread_mutex_unlock(&server_started_mtx);
if (CHECK_FAIL(err < 0)) {
perror("Failed to listed on socket");
return NULL;
}
@ -248,7 +258,14 @@ void test_tcp_rtt(void)
if (CHECK_FAIL(server_fd < 0))
goto close_cgroup_fd;
pthread_create(&tid, NULL, server_thread, (void *)&server_fd);
if (CHECK_FAIL(pthread_create(&tid, NULL, server_thread,
(void *)&server_fd)))
goto close_cgroup_fd;
pthread_mutex_lock(&server_started_mtx);
pthread_cond_wait(&server_started, &server_started_mtx);
pthread_mutex_unlock(&server_started_mtx);
CHECK_FAIL(run_test(cgroup_fd, server_fd));
close(server_fd);
close_cgroup_fd: