Currently, UDP exchange is prone to failure when cmd attempt to send data while socat in bkg is not ready. Since, the behavior is probabilistic, this can result in flakiness for XDP tests. While testing test_xdp_native_tx_mb() on netdevsim, a failure rate of around 1% in 500 500 iterations was observed.

Use wait_port_listen() to ensure that the bkg socat is started and ready to receive before cmd start sending. With proposed changes, a re-run of the same test passed 100% of time.

Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Mohsin Bashir mohsin.bashr@gmail.com --- tools/testing/selftests/drivers/net/xdp.py | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/drivers/net/xdp.py b/tools/testing/selftests/drivers/net/xdp.py index 887d662ad128..1dd8bf3bf6c9 100755 --- a/tools/testing/selftests/drivers/net/xdp.py +++ b/tools/testing/selftests/drivers/net/xdp.py @@ -13,7 +13,7 @@ from enum import Enum

from lib.py import ksft_run, ksft_exit, ksft_eq, ksft_ne, ksft_pr from lib.py import KsftFailEx, NetDrvEpEnv, EthtoolFamily, NlError -from lib.py import bkg, cmd, rand_port +from lib.py import bkg, cmd, rand_port, wait_port_listen from lib.py import ip, bpftool, defer

@@ -70,6 +70,7 @@ def _exchg_udp(cfg, port, test_string): tx_udp_cmd = f"echo -n {test_string} | socat -t 2 -u STDIN UDP:{cfg.baddr}:{port}"

with bkg(rx_udp_cmd, exit_wait=True) as nc: + wait_port_listen(port, proto="udp") cmd(tx_udp_cmd, host=cfg.remote, shell=True)

return nc.stdout.strip() @@ -310,6 +311,7 @@ def test_xdp_native_tx_mb(cfg): tx_udp = f"echo {test_string} | socat -t 2 -u STDIN UDP:{cfg.baddr}:{port}"

with bkg(rx_udp, host=cfg.remote, exit_wait=True) as rnc: + wait_port_listen(port, proto="udp", host=cfg.remote) cmd(tx_udp, host=cfg.remote, shell=True)

stats = _get_stats(prog_info['maps']['map_xdp_stats'])