Re: [PATCH v1 0/3] kunit: Deferred action helpers

From: Maxime Ripard <maxime@cerno.tech>
To: David Gow <davidgow@google.com>
Cc: Matti Vaittinen <mazziesaccount@gmail.com>,
	Brendan Higgins <brendan.higgins@linux.dev>,
	Stephen Boyd <sboyd@kernel.org>,
	Shuah Khan <skhan@linuxfoundation.org>,
	Daniel Latypov <dlatypov@google.com>, Rae Moar <rmoar@google.com>,
	Benjamin Berg <benjamin@sipsolutions.net>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	Jonathan Cameron <jic23@kernel.org>,
	linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
	kunit-dev@googlegroups.com
Subject: Re: [PATCH v1 0/3] kunit: Deferred action helpers
Date: Tue, 25 Apr 2023 17:23:50 +0200	[thread overview]
Message-ID: <knlcj7ub477vbdhi4jkhxg6eltrluffli2gett4t4w4ed4cztr@qlxpd4rmgx3g> (raw)
In-Reply-To: <20230421084226.2278282-1-davidgow@google.com>

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Hi,

On Fri, Apr 21, 2023 at 04:42:23PM +0800, David Gow wrote:
> This is v1 of the KUnit deferred actions API, which implements an
> equivalent of devm_add_action[1] on top of KUnit managed resources. This
> provides a simple way of scheduling a function to run when the test
> terminates (whether successfully, or with an error). It's therefore very
> useful for freeing resources, or otherwise cleaning up.
> 
> The notable changes since RFCv2[2] are:
> - Got rid of the 'cancellation token' concept. It was overcomplicated,
>   and we can add it back if we need to.
> - kunit_add_action() therefore now returns 0 on success, and an error
>   otherwise (like devm_add_action()). Though you may wish to use:
> - Added kunit_add_action_or_reset(), which will call the deferred
>   function if an error occurs. (See devm_add_action_or_reset()). This
>   also returns an error on failure, which can be asserted safely.
> - Got rid of the function pointer typedef. Personally, I liked it, but
>   it's more typedef-y than most kernel code.
> - Got rid of the 'internal_gfp' argument: all internal state is now
>   allocated with GFP_KERNEL. The main KUnit resource API can be used
>   instead if this doesn't work for your use-case.
> 
> I'd love to hear any further thoughts!

I've converted the KMS kunit tests to use that API when relevant, and
it works like a charm and is super usable, thanks so much.

One improvement we could do as a second step is to provide a
kunit_action_t type or something to make casting kfree-like functions
easier, but it's already great overall.

Reviewed-by: Maxime Ripard <maxime@cerno.tech>
Tested-by: Maxime Ripard <maxime@cerno.tech>

Thanks again,
Maxime

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