selftests: net: ksft: support marking tests as disruptive

Add new @ksft_disruptive decorator to mark the tests that might
be disruptive to the system. Depending on how well the previous
test works in the CI we might want to disable disruptive tests
by default and only let the developers run them manually.

KSFT framework runs disruptive tests by default. DISRUPTIVE=False
environment (or config file) can be used to disable these tests.
ksft_setup should be called by the test cases that want to use
new decorator (ksft_setup is only called via NetDrvEnv/NetDrvEpEnv for now).

In the future we can add similar decorators to, for example, avoid
running slow tests all the time. And/or have some option to run
only 'fast' tests for some sort of smoke test scenario.

$ DISRUPTIVE=False ./stats.py
KTAP version 1
1..5
ok 1 stats.check_pause
ok 2 stats.check_fec
ok 3 stats.pkt_byte_sum
ok 4 stats.qstat_by_ifindex
ok 5 stats.check_down # SKIP marked as disruptive
# Totals: pass:4 fail:0 xfail:0 xpass:0 skip:1 error:0

v3:
- parse yes and properly treat non-zero nums as true (Petr)

v2:
- convert from cli argument to env variable (Jakub)

Signed-off-by: Stanislav Fomichev <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

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

···
 import time
 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 NetNS, NetdevSimDev
 from .remote import Remote
···
 
     src_dir = Path(src_path).parent.resolve()
     if not (src_dir / "net.config").exists():
-        return env
+        return ksft_setup(env)
 
     with open((src_dir / "net.config").as_posix(), 'r') as fp:
         for line in fp.readlines():
···
             if len(pair) != 2:
                 raise Exception("Can't parse configuration line:", full_file)
             env[pair[0]] = pair[1]
-    return env
+    return ksft_setup(env)
 
 
 class NetDrvEnv:

tools/testing/selftests/drivers/net/stats.py

···
 import errno
 from lib.py import ksft_run, ksft_exit, ksft_pr
 from lib.py import ksft_ge, ksft_eq, ksft_in, ksft_true, ksft_raises, KsftSkipEx, KsftXfailEx
+from lib.py import ksft_disruptive
 from lib.py import EthtoolFamily, NetdevFamily, RtnlFamily, NlError
 from lib.py import NetDrvEnv
 from lib.py import ip, defer
···
     ksft_eq(cm.exception.nl_msg.extack['bad-attr'], '.ifindex')
 
 
+@ksft_disruptive
 def check_down(cfg) -> None:
     try:
         qstat = netfam.qstats_get({"ifindex": cfg.ifindex}, dump=True)[0]

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

···
 # SPDX-License-Identifier: GPL-2.0
 
 import builtins
+import functools
 import inspect
 import sys
 import time
···
 
 KSFT_RESULT = None
 KSFT_RESULT_ALL = True
+KSFT_DISRUPTIVE = True
 
 
 class KsftFailEx(Exception):
···
             for line in tb.strip().split('\n'):
                 ksft_pr("Defer Exception|", line)
             KSFT_RESULT = False
+
+
+def ksft_disruptive(func):
+    """
+    Decorator that marks the test as disruptive (e.g. the test
+    that can down the interface). Disruptive tests can be skipped
+    by passing DISRUPTIVE=False environment variable.
+    """
+
+    @functools.wraps(func)
+    def wrapper(*args, **kwargs):
+        if not KSFT_DISRUPTIVE:
+            raise KsftSkipEx(f"marked as disruptive")
+        return func(*args, **kwargs)
+    return wrapper
+
+
+def ksft_setup(env):
+    """
+    Setup test framework global state from the environment.
+    """
+
+    def get_bool(env, name):
+        value = env.get(name, "").lower()
+        if value in ["yes", "true"]:
+            return True
+        if value in ["no", "false"]:
+            return False
+        try:
+            return bool(int(value))
+        except:
+            raise Exception(f"failed to parse {name}")
+
+    if "DISRUPTIVE" in env:
+        global KSFT_DISRUPTIVE
+        KSFT_DISRUPTIVE = get_bool(env, "DISRUPTIVE")
+
+    return env
 
 
 def ksft_run(cases=None, globs=None, case_pfx=None, args=()):