Re: [PATCH v12 net-next 3/3] selftests: drivers/net: Implement ptp4l sync test using netdevsim

[Hangbin Liu <hangbin.liu@linux.dev>]

On Sun, Nov 08, 2026 at 09:15:03PM +0100, Maciek Machnikowski wrote:
> Add PTP synchronization test using ptp4l and netdevsim.
> The test uses the NetDrvEpEnv to link a local netdevsim
> device to a remote endpoint, runs ptp4l as leader and follower
> on the two ends, and waits for the follower to report the
> synchronized state (s2).
> 
> Reviewed-by: Mina Almasry <almasrymina@google.com>
> Signed-off-by: Maciek Machnikowski <maciek@machnikowski.net>
> ---
>  tools/testing/selftests/drivers/net/Makefile |   1 +
>  tools/testing/selftests/drivers/net/config   |   1 +
>  tools/testing/selftests/drivers/net/ptp.py   | 112 +++++++++++++++++++
>  3 files changed, 114 insertions(+)
>  create mode 100755 tools/testing/selftests/drivers/net/ptp.py
> 
> diff --git a/tools/testing/selftests/drivers/net/Makefile b/tools/testing/selftests/drivers/net/Makefile
> index 79c6f998e704..ed41a69ef6ad 100644
> --- a/tools/testing/selftests/drivers/net/Makefile
> +++ b/tools/testing/selftests/drivers/net/Makefile
> @@ -23,6 +23,7 @@ TEST_PROGS := \
>  	ping.py \
>  	pppoe_gro.py \
>  	psp.py \
> +	ptp.py \
>  	queues.py \
>  	ring_reconfig.py \
>  	rss_key.py \
> diff --git a/tools/testing/selftests/drivers/net/config b/tools/testing/selftests/drivers/net/config
> index 4838adf27fa1..30e69446d41d 100644
> --- a/tools/testing/selftests/drivers/net/config
> +++ b/tools/testing/selftests/drivers/net/config
> @@ -21,6 +21,7 @@ CONFIG_NET_SCH_INGRESS=y
>  CONFIG_NET_SCH_PRIO=m
>  CONFIG_PPP=y
>  CONFIG_PPPOE=y
> +CONFIG_PTP_1588_CLOCK_MOCK=y
>  CONFIG_TLS=y
>  CONFIG_VLAN_8021Q=m
>  CONFIG_XDP_SOCKETS=y
> diff --git a/tools/testing/selftests/drivers/net/ptp.py b/tools/testing/selftests/drivers/net/ptp.py
> new file mode 100755
> index 000000000000..1065bd42ba53
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/net/ptp.py
> @@ -0,0 +1,112 @@
> +#!/usr/bin/env python3
> +# SPDX-License-Identifier: GPL-2.0-only
> +#
> +# By Maciek Machnikowski <maciek@machnikowski.net> (c) 2026
> +
> +"""
> +Test suite for PTP sync using ptp4l.
> +
> +Start a ptp4l leader and follower and check that the follower locks onto the
> +leader (state s2)
> +"""
> +
> +import time
> +
> +from lib.py import (
> +    KsftSkipEx,
> +    NetDrvEpEnv,
> +    bkg,
> +    cmd,
> +    defer,
> +    fd_read_timeout,
> +    ksft_exit,
> +    ksft_pr,
> +    ksft_run,
> +    ksft_true,
> +)
> +
> +PTP4L_SYNC_TIMEOUT = 40
> +
> +
> +def _require_hw_timestamping(ifname, host=None):
> +    """Skip the test unless ifname supports HW TX and RX timestamping."""
> +    end = "Remote" if host else "Local"
> +    ts_info = cmd(f"ethtool -T {ifname}", host=host).stdout
> +    if "hardware-transmit" not in ts_info or "hardware-receive" not in ts_info:
> +        raise KsftSkipEx(
> +            f"{end} device does not support hardware timestamping")
> +
> +
> +def _poll_follower_sync(follower, timeout):
> +    """Read the follower stdout pipe until ptp4l reports sync state s2.
> +
> +    Returns a tuple (synced, output) where output is the text read so far.
> +    The synchronized ptp4l log line looks like this:
> +    ptp4l[18374.558]: master offset        844 s2 freq    +822 path delay       521
> +    """
> +    fd_file = follower.proc.stdout
> +    fd = fd_file.fileno()
> +    buf = b""
> +    deadline = time.monotonic() + timeout
> +    while time.monotonic() < deadline:
> +        if b" s2 " in buf:
> +            break
> +        if follower.proc.poll() is not None:
> +            chunk = fd_file.read()
> +            if chunk:
> +                buf += chunk
> +            break
> +        try:
> +            remaining = deadline - time.monotonic()
> +            buf += fd_read_timeout(fd, max(0, min(1, remaining)))
> +        except TimeoutError:
> +            continue
> +    return b" s2 " in buf, buf.decode("utf-8", "replace")
> +
> +
> +def ptp_sync_test(cfg):
> +    """Verify ptp4l leader/follower synchronization reaches state s2."""
> +    cfg.require_cmd("ptp4l", remote=True)
> +    cfg.require_cmd("ethtool", remote=True)
> +
> +    _require_hw_timestamping(cfg.ifname)
> +    _require_hw_timestamping(cfg.remote_ifname, host=cfg.remote)
> +
> +    local_dir = cmd("mktemp -d").stdout.strip()
> +    remote_dir = cmd("mktemp -d", host=cfg.remote).stdout.strip()
> +    defer(cmd, f"rm -rf {local_dir}")
> +    defer(cmd, f"rm -rf {remote_dir}", host=cfg.remote)
> +
> +    leader_cmd = (f"ptp4l -i {cfg.remote_ifname} -m -2 "
> +                  f"--uds_address {remote_dir}/ptp4l "
> +                  f"--uds_ro_address {remote_dir}/ptp4lro")
> +    follower_cmd = (f"ptp4l -i {cfg.ifname} -m -s -2 "
> +                    f"--uds_address {local_dir}/ptp4l "
> +                    f"--uds_ro_address {local_dir}/ptp4lro")
> +
> +    # bkg() can't reliably signal the remote ptp4l over SSH (no pty), so
> +    # kill it by pattern explicitly in addition to the normal teardown.
> +    # pkill exits 1 when ptp4l already terminated, so don't treat it as fatal.
> +    defer(cmd, f'pkill -INT -f "{leader_cmd}"', host=cfg.remote, fail=False)
> +
> +    with bkg(leader_cmd, host=cfg.remote), \
> +         bkg(follower_cmd) as follower:
> +        synced, output = _poll_follower_sync(follower, PTP4L_SYNC_TIMEOUT)
> +
> +    if not synced:
> +        ksft_pr(f"ptp4l follower did not reach locked state (s2) within "
> +                f"{PTP4L_SYNC_TIMEOUT}s")
> +        tail = output.strip().split("\n")[-10:]
> +        ksft_pr("Follower log (last 10 lines): " + " | ".join(tail))
> +    ksft_true(synced, "PTP sync timeout")
> +
> +
> +def main():
> +    """Run ksft tests."""
> +    with NetDrvEpEnv(__file__) as cfg:
> +        ksft_run([ptp_sync_test], args=(cfg, ))
> +    ksft_exit()
> +
> +
> +if __name__ == "__main__":
> +    main()
> -- 
> 2.56.0
> 

Tested-by: Hangbin Liu <liuhangbin@kylinos.cn>
Reviewed-by: Hangbin Liu <liuhangbin@kylinos.cn>