linux-kernel - Re: [PATCH v3 1/2] kunit: drop assumption in kunit-log-test about current suite

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Message-ID: <CAFd5g460dsFZrxio5P6VX5LVpFMC6Runwos7PQtTuNpoOdPZCw@mail.gmail.com>
Date:   Tue, 31 Aug 2021 13:42:35 -0700
From:   Brendan Higgins <brendanhiggins@...gle.com>
To:     Daniel Latypov <dlatypov@...gle.com>
Cc:     davidgow@...gle.com, linux-kernel@...r.kernel.org,
        kunit-dev@...glegroups.com, linux-kselftest@...r.kernel.org,
        skhan@...uxfoundation.org
Subject: Re: [PATCH v3 1/2] kunit: drop assumption in kunit-log-test about
 current suite

On Tue, Aug 31, 2021 at 10:19 AM Daniel Latypov <dlatypov@...gle.com> wrote:
>
> This test assumes that the declared kunit_suite object is the exact one
> which is being executed, which KUnit will not guarantee [1].
>
> Specifically, `suite->log` is not initialized until a suite object is
> executed. So if KUnit makes a copy of the suite and runs that instead,
> this test dereferences an invalid pointer and (hopefully) segfaults.
>
> N.B. since we no longer assume this, we can no longer verify that
> `suite->log` is *not* allocated during normal execution.
>
> An alternative to this patch that would allow us to test that would
> require exposing an API for the current test to get its current suite.
> Exposing that for one internal kunit test seems like overkill, and
> grants users more footguns (e.g. reusing a test case in multiple suites
> and changing behavior based on the suite name, dynamically modifying the
> setup/cleanup funcs, storing/reading stuff out of the suite->log, etc.).
>
> [1] In a subsequent patch, KUnit will allow running subsets of test
> cases within a suite by making a copy of the suite w/ the filtered test
> list. But there are other reasons KUnit might execute a copy, e.g. if it
> ever wants to support parallel execution of different suites, recovering
> from errors and restarting suites
>
> Signed-off-by: Daniel Latypov <dlatypov@...gle.com>

Reviewed-by: Brendan Higgins <brendanhiggins@...gle.com>