selftests: net-drv: stats: sanity check FEC histogram

Simple tests to validate kernel's output. FEC bin range should be valid
means high boundary should be not less than low boundary. Bin boundaries
have to be provided as well as error counter value. Per-plane value
should match bin's value.

Signed-off-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Link: https://patch.msgid.link/20250924124037.1508846-6-vadim.fedorenko@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 33 insertions, 2 deletions

diff --git a/tools/testing/selftests/drivers/net/stats.py b/tools/testing/selftests/drivers/net/stats.py
index c2bb5d3f1ca1..04d0a2a13e73 100755
--- a/tools/testing/selftests/drivers/net/stats.py
+++ b/tools/testing/selftests/drivers/net/stats.py
@@ -57,6 +57,36 @@ def check_fec(cfg) -> None:
     ksft_true(data['stats'], "driver does not report stats")
 
 
+def check_fec_hist(cfg) -> None:
+    """
+    Check that drivers which support FEC histogram statistics report
+    reasonable values.
+    """
+
+    try:
+        data = ethnl.fec_get({"header": {"dev-index": cfg.ifindex,
+                                         "flags": {'stats'}}})
+    except NlError as e:
+        if e.error == errno.EOPNOTSUPP:
+            raise KsftSkipEx("FEC not supported by the device") from e
+        raise
+    if 'stats' not in data:
+        raise KsftSkipEx("FEC stats not supported by the device")
+    if 'hist' not in data['stats']:
+        raise KsftSkipEx("FEC histogram not supported by the device")
+
+    hist = data['stats']['hist']
+    for fec_bin in hist:
+        for key in ['bin-low', 'bin-high', 'bin-val']:
+            ksft_in(key, fec_bin,
+	            "Drivers should always report FEC bin range and value")
+        ksft_ge(fec_bin['bin-high'], fec_bin['bin-low'],
+                "FEC bin range should be valid")
+        if 'bin-val-per-lane' in fec_bin:
+            ksft_eq(sum(fec_bin['bin-val-per-lane']), fec_bin['bin-val'],
+                    "FEC bin value should be equal to sum of per-plane values")
+
+
 def pkt_byte_sum(cfg) -> None:
     """
     Check that qstat and interface stats match in value.
@@ -279,8 +309,9 @@ def main() -> None:
     """ Ksft boiler plate main """
 
     with NetDrvEnv(__file__, queue_count=100) as cfg:
-        ksft_run([check_pause, check_fec, pkt_byte_sum, qstat_by_ifindex,
-                  check_down, procfs_hammer, procfs_downup_hammer],
+        ksft_run([check_pause, check_fec, check_fec_hist, pkt_byte_sum,
+		  qstat_by_ifindex, check_down, procfs_hammer,
+		  procfs_downup_hammer],
                  args=(cfg, ))
     ksft_exit()