selftests: drv-net: test RSS Netlink notifications

Test that changing the RSS config generates Netlink notifications.

  # ./tools/testing/selftests/drivers/net/hw/rss_api.py
  TAP version 13
  1..2
  ok 1 rss_api.test_rxfh_indir_ntf
  ok 2 rss_api.test_rxfh_indir_ctx_ntf
  # Totals: pass:2 fail:0 xfail:0 xpass:0 skip:0 error:0

Link: https://patch.msgid.link/20250623231720.3124717-9-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/drivers/net/hw/rss_api.py

@@ -0,0 +1,89 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+"""
+API level tests for RSS (mostly Netlink vs IOCTL).
+"""
+
+import glob
+from lib.py import ksft_run, ksft_exit, ksft_eq, ksft_is, ksft_ne
+from lib.py import KsftSkipEx, KsftFailEx
+from lib.py import defer, ethtool
+from lib.py import EthtoolFamily
+from lib.py import NetDrvEnv
+
+
+def _ethtool_create(cfg, act, opts):
+    output = ethtool(f"{act} {cfg.ifname} {opts}").stdout
+    # Output will be something like: "New RSS context is 1" or
+    # "Added rule with ID 7", we want the integer from the end
+    return int(output.split()[-1])
+
+
+def test_rxfh_indir_ntf(cfg):
+    """
+    Check that Netlink notifications are generated when RSS indirection
+    table was modified.
+    """
+
+    qcnt = len(glob.glob(f"/sys/class/net/{cfg.ifname}/queues/rx-*"))
+    if qcnt < 2:
+        raise KsftSkipEx(f"Local has only {qcnt} queues")
+
+    ethnl = EthtoolFamily()
+    ethnl.ntf_subscribe("monitor")
+
+    ethtool(f"--disable-netlink -X {cfg.ifname} weight 0 1")
+    reset = defer(ethtool, f"-X {cfg.ifname} default")
+
+    ntf = next(ethnl.poll_ntf(duration=0.2), None)
+    if ntf is None:
+        raise KsftFailEx("No notification received")
+    ksft_eq(ntf["name"], "rss-ntf")
+    ksft_eq(set(ntf["msg"]["indir"]), {1})
+
+    reset.exec()
+    ntf = next(ethnl.poll_ntf(duration=0.2), None)
+    if ntf is None:
+        raise KsftFailEx("No notification received after reset")
+    ksft_eq(ntf["name"], "rss-ntf")
+    ksft_is(ntf["msg"].get("context"), None)
+    ksft_ne(set(ntf["msg"]["indir"]), {1})
+
+
+def test_rxfh_indir_ctx_ntf(cfg):
+    """
+    Check that Netlink notifications are generated when RSS indirection
+    table was modified on an additional RSS context.
+    """
+
+    qcnt = len(glob.glob(f"/sys/class/net/{cfg.ifname}/queues/rx-*"))
+    if qcnt < 2:
+        raise KsftSkipEx(f"Local has only {qcnt} queues")
+
+    ctx_id = _ethtool_create(cfg, "-X", "context new")
+    defer(ethtool, f"-X {cfg.ifname} context {ctx_id} delete")
+
+    ethnl = EthtoolFamily()
+    ethnl.ntf_subscribe("monitor")
+
+    ethtool(f"--disable-netlink -X {cfg.ifname} context {ctx_id} weight 0 1")
+
+    ntf = next(ethnl.poll_ntf(duration=0.2), None)
+    if ntf is None:
+        raise KsftFailEx("No notification received")
+    ksft_eq(ntf["name"], "rss-ntf")
+    ksft_eq(ntf["msg"].get("context"), ctx_id)
+    ksft_eq(set(ntf["msg"]["indir"]), {1})
+
+
+def main() -> None:
+    """ Ksft boiler plate main """
+
+    with NetDrvEnv(__file__, nsim_test=False) as cfg:
+        ksft_run(globs=globals(), case_pfx={"test_"}, args=(cfg, ))
+    ksft_exit()
+
+
+if __name__ == "__main__":
+    main()