| Message ID | 20200314013932.4035712-1-andriin@fb.com |
|---|---|
| State | Accepted |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [bpf-next,1/3] selftests/bpf: fix race in tcp_rtt test | expand |
On Fri, Mar 13, 2020 at 06:39:30PM -0700, Andrii Nakryiko wrote: > Previous attempt to make tcp_rtt more robust introduced a new race, in which > server_done might be set to true before server can actually accept any > connection. Fix this by unconditionally waiting for accept(). Given socket is > non-blocking, if there are any problems with client side, it should eventually > close listening FD and let server thread exit with failure. > > Fixes: 4cd729fa022c ("selftests/bpf: Make tcp_rtt test more robust to failures") > Signed-off-by: Andrii Nakryiko <andriin@fb.com> > --- > tools/testing/selftests/bpf/prog_tests/tcp_rtt.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/tools/testing/selftests/bpf/prog_tests/tcp_rtt.c b/tools/testing/selftests/bpf/prog_tests/tcp_rtt.c > index e08f6bb17700..e56b52ab41da 100644 > --- a/tools/testing/selftests/bpf/prog_tests/tcp_rtt.c > +++ b/tools/testing/selftests/bpf/prog_tests/tcp_rtt.c > @@ -226,7 +226,7 @@ static void *server_thread(void *arg) > return ERR_PTR(err); > } > > - while (!server_done) { > + while (true) { > client_fd = accept(fd, (struct sockaddr *)&addr, &len); > if (client_fd == -1 && errno == EAGAIN) { > usleep(50); > @@ -272,7 +272,7 @@ void test_tcp_rtt(void) > CHECK_FAIL(run_test(cgroup_fd, server_fd)); > > server_done = true; > - pthread_join(tid, &server_res); > + CHECK_FAIL(pthread_join(tid, &server_res)); From looking at run_test(), I suspect without accept and server_thread, this may also work: listen(server_fd, 1); run_test(cgroup_fd, server_fd); close(server_fd); This change lgtm since it is NONBLOCK. Ideally, may be it should also be time limited by epoll or setsockopt(SO_RCVTIMEO) in the future. Acked-by: Martin KaFai Lau <kafai@fb.com>
On 3/14/20 2:39 AM, Andrii Nakryiko wrote: > Previous attempt to make tcp_rtt more robust introduced a new race, in which > server_done might be set to true before server can actually accept any > connection. Fix this by unconditionally waiting for accept(). Given socket is > non-blocking, if there are any problems with client side, it should eventually > close listening FD and let server thread exit with failure. > > Fixes: 4cd729fa022c ("selftests/bpf: Make tcp_rtt test more robust to failures") > Signed-off-by: Andrii Nakryiko <andriin@fb.com> Series applied, thanks!
diff --git a/tools/testing/selftests/bpf/prog_tests/tcp_rtt.c b/tools/testing/selftests/bpf/prog_tests/tcp_rtt.c index e08f6bb17700..e56b52ab41da 100644 --- a/tools/testing/selftests/bpf/prog_tests/tcp_rtt.c +++ b/tools/testing/selftests/bpf/prog_tests/tcp_rtt.c @@ -226,7 +226,7 @@ static void *server_thread(void *arg) return ERR_PTR(err); } - while (!server_done) { + while (true) { client_fd = accept(fd, (struct sockaddr *)&addr, &len); if (client_fd == -1 && errno == EAGAIN) { usleep(50); @@ -272,7 +272,7 @@ void test_tcp_rtt(void) CHECK_FAIL(run_test(cgroup_fd, server_fd)); server_done = true; - pthread_join(tid, &server_res); + CHECK_FAIL(pthread_join(tid, &server_res)); CHECK_FAIL(IS_ERR(server_res)); close_server_fd:
Previous attempt to make tcp_rtt more robust introduced a new race, in which server_done might be set to true before server can actually accept any connection. Fix this by unconditionally waiting for accept(). Given socket is non-blocking, if there are any problems with client side, it should eventually close listening FD and let server thread exit with failure. Fixes: 4cd729fa022c ("selftests/bpf: Make tcp_rtt test more robust to failures") Signed-off-by: Andrii Nakryiko <andriin@fb.com> --- tools/testing/selftests/bpf/prog_tests/tcp_rtt.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)