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References: <20220402043530.923747-1-davidgow@google.com> <20220402043530.923747-2-davidgow@google.com>
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From:   Brendan Higgins <brendanhiggins@google.com>
Date:   Tue, 26 Apr 2022 17:31:57 -0400
Message-ID: <CAFd5g46UfmrE-D9PKfGJsgZBnCUi9-Z82tu1=4ZQzCCj0VcQCw@mail.gmail.com>
Subject: Re: [PATCH v2 2/2] kunit: Rework kunit_resource allocation policy
To:     David Gow <davidgow@google.com>
Cc:     Daniel Latypov <dlatypov@google.com>,
        Shuah Khan <skhan@linuxfoundation.org>,
        kunit-dev@googlegroups.com, linux-kselftest@vger.kernel.org,
        linux-kernel@vger.kernel.org
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On Sat, Apr 2, 2022 at 12:35 AM 'David Gow' via KUnit Development
<kunit-dev@googlegroups.com> wrote:
>
> KUnit's test-managed resources can be created in two ways:
> - Using the kunit_add_resource() family of functions, which accept a
>   struct kunit_resource pointer, typically allocated statically or on
>   the stack during the test.
> - Using the kunit_alloc_resource() family of functions, which allocate a
>   struct kunit_resource using kzalloc() behind the scenes.
>
> Both of these families of functions accept a 'free' function to be
> called when the resource is finally disposed of.
>
> At present, KUnit will kfree() the resource if this 'free' function is
> specified, and will not if it is NULL. However, this can lead
> kunit_alloc_resource() to leak memory (if no 'free' function is passed
> in), or kunit_add_resource() to incorrectly kfree() memory which was
> allocated by some other means (on the stack, as part of a larger
> allocation, etc), if a 'free' function is provided.
>
> Instead, always kfree() if the resource was allocated with
> kunit_alloc_resource(), and never kfree() if it was passed into
> kunit_add_resource() by the user. (If the user of kunit_add_resource()
> wishes the resource be kfree()ed, they can call kfree() on the resource
> from within the 'free' function.
>
> This is implemented by adding a 'should_free' member to
> struct kunit_resource and setting it appropriately. To facilitate this,
> the various resource add/alloc functions have been refactored somewhat,
> making them all call a __kunit_add_resource() helper after setting the
> 'should_free' member appropriately. In the process, all other functions
> have been made static inline functions.
>
> Signed-off-by: David Gow <davidgow@google.com>
> Tested-by: Daniel Latypov <dlatypov@google.com>

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