selftests: drv-net: assume stats refresh is 0 if no ethtool -c support

Tests using HW stats wait for them to stabilize, using data from
ethtool -c as the delay. Not all drivers implement ethtool -c
so handle the errors gracefully.

Reviewed-by: Andrew Lunn <[email protected]>
Reviewed-by: Willem de Bruijn <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: kuba-moo

tools/testing/selftests/drivers/net/lib/py/env.py

@@ -5,7 +5,7 @@
 from pathlib import Path
 from lib.py import KsftSkipEx, KsftXfailEx
 from lib.py import ksft_setup
-from lib.py import cmd, ethtool, ip
+from lib.py import cmd, ethtool, ip, CmdExitFailure
 from lib.py import NetNS, NetdevSimDev
 from .remote import Remote
 
@@ -234,7 +234,12 @@ def wait_hw_stats_settle(self):
         Good drivers will tell us via ethtool what their sync period is.
         """
         if self._stats_settle_time is None:
-            data = ethtool("-c " + self.ifname, json=True)[0]
+            data = {}
+            try:
+                data = ethtool("-c " + self.ifname, json=True)[0]
+            except CmdExitFailure as e:
+                if "Operation not supported" not in e.cmd.stderr:
+                    raise
 
             self._stats_settle_time = 0.025 + \
                 data.get('stats-block-usecs', 0) / 1000 / 1000

tools/testing/selftests/net/lib/py/utils.py

@@ -10,7 +10,9 @@
 
 
 class CmdExitFailure(Exception):
-    pass
+    def __init__(self, msg, cmd_obj):
+        super().__init__(msg)
+        self.cmd = cmd_obj
 
 
 class cmd:
@@ -48,7 +50,7 @@ def process(self, terminate=True, fail=None, timeout=5):
             if len(stderr) > 0 and stderr[-1] == "\n":
                 stderr = stderr[:-1]
             raise CmdExitFailure("Command failed: %s\nSTDOUT: %s\nSTDERR: %s" %
-                                 (self.proc.args, stdout, stderr))
+                                 (self.proc.args, stdout, stderr), self)
 
 
 class bkg(cmd):