From: Daniel Latypov <dlatypov@google.com>
To: brendanhiggins@google.com
Cc: davidgow@google.com, linux-kernel@vger.kernel.org,
kunit-dev@googlegroups.com, linux-kselftest@vger.kernel.org,
skhan@linuxfoundation.org, Daniel Latypov <dlatypov@google.com>
Subject: [PATCH v4 3/3] kunit: tool: fix unintentional statefulness in run_kernel()
Date: Fri, 5 Feb 2021 16:08:54 -0800 [thread overview]
Message-ID: <20210206000854.2037923-4-dlatypov@google.com> (raw)
In-Reply-To: <20210206000854.2037923-1-dlatypov@google.com>
This is a bug that has been present since the first version of this
code.
Using [] as a default parameter is dangerous, since it's mutable.
Example using the REPL:
>>> def bad(param = []):
... param.append(len(param))
... print(param)
...
>>> bad()
[0]
>>> bad()
[0, 1]
This wasn't a concern in the past since it would just keep appending the
same values to it.
E.g. before, `args` would just grow in size like:
[mem=1G', 'console=tty']
[mem=1G', 'console=tty', mem=1G', 'console=tty']
But with now filter_glob, this is more dangerous, e.g.
run_kernel(filter_glob='my-test*') # default modified here
run_kernel() # filter_glob still applies here!
That earlier `filter_glob` will affect all subsequent calls that don't
specify `args`.
Note: currently the kunit tool only calls run_kernel() at most once, so
it's not possible to trigger any negative side-effects right now.
Fixes: 6ebf5866f2e8 ("kunit: tool: add Python wrappers for running KUnit tests")
Signed-off-by: Daniel Latypov <dlatypov@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
---
tools/testing/kunit/kunit_kernel.py | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/tools/testing/kunit/kunit_kernel.py b/tools/testing/kunit/kunit_kernel.py
index 71a5f5c1750b..f309a33256cd 100644
--- a/tools/testing/kunit/kunit_kernel.py
+++ b/tools/testing/kunit/kunit_kernel.py
@@ -203,7 +203,9 @@ class LinuxSourceTree(object):
return False
return self.validate_config(build_dir)
- def run_kernel(self, args=[], build_dir='', filter_glob='', timeout=None) -> Iterator[str]:
+ def run_kernel(self, args=None, build_dir='', filter_glob='', timeout=None) -> Iterator[str]:
+ if not args:
+ args = []
args.extend(['mem=1G', 'console=tty'])
if filter_glob:
args.append('kunit.filter_glob='+filter_glob)
--
2.30.0.478.g8a0d178c01-goog
next prev parent reply other threads:[~2021-02-06 3:17 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-06 0:08 [PATCH v4 0/3] kunit: support running subsets of test suites from kunit.py Daniel Latypov
2021-02-06 0:08 ` [PATCH v4 1/3] kunit: add kunit.filter_glob cmdline option to filter suites Daniel Latypov
2021-02-06 0:08 ` [PATCH v4 2/3] kunit: tool: add support for filtering suites by glob Daniel Latypov
2021-02-06 0:08 ` Daniel Latypov [this message]
2021-02-08 18:53 ` [PATCH v4 0/3] kunit: support running subsets of test suites from kunit.py Brendan Higgins
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