Re: [PATCH v2] reset: Add KUnit test cases

[Philipp Zabel <p.zabel@pengutronix.de>]

On Mo, 2026-11-02 at 23:52 +0800, Tzung-Bi Shih wrote:
> Since commit 9035073d0ef1 ("reset: convert reset core to using firmware
> nodes"), reset suppliers and consumers can be wired up using software
> nodes without requiring Device Tree or hardware devices.  Leverage this
> to add KUnit test cases for the reset controller framework.
> 
> The test cases cover the following scenarios:
> 
> - Basic: Verifies that a consumer can acquire a reset control via
>   fwnode and perform reset, assert, deassert, status, release, and
>   acquire operations.
> - Use After Unregister: Verifies that after the supplier unregisters
>   the reset_controller_dev while a consumer still holds a reset_control
>   handle, subsequent consumer operations fail safely with -ENODEV.
> - Concurrent Unregister: Verifies that unregistering the
>   reset_controller_dev concurrently with an in-flight reset operation
>   waits for the active operation to complete before returning.
> 
> Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
> ---
> Test:
> $ ./tools/testing/kunit/kunit.py run \
>         --kconfig_add CONFIG_RESET_CONTROLLER=y \
>         --kconfig_add CONFIG_RESET_KUNIT_TEST=y \
>         reset_test
> ---
> v2:
> - Separate out from the revocable series.
> - Add reset_test_exit() to clean up rstc and rcdev on test exit or
>   assertion failure.
> - Clean up kthreads on error paths in reset_test_concurrent_unregister().
> 
> v1: https://lore.kernel.org/all/20261011121246.162759-5-tzungbi@kernel.org
> ---
>  drivers/reset/Kconfig     |   5 +
>  drivers/reset/Makefile    |   2 +
>  drivers/reset/core-test.c | 351 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 358 insertions(+)
>  create mode 100644 drivers/reset/core-test.c
> 
[...]
> diff --git a/drivers/reset/core-test.c b/drivers/reset/core-test.c
> new file mode 100644
> index 000000000000..613db78040c6
> --- /dev/null
> +++ b/drivers/reset/core-test.c
> @@ -0,0 +1,351 @@
[...]
> +static void reset_test_concurrent_unregister(struct kunit *test)
> +{
> +	struct reset_test_context *rtc = test->priv;
> +	struct test_concurrent_unregister_context *ctx;
> +	int i, ret, val;
> +
> +	rtc->rcdev.ops = &reset_test_concurrent_unregister_ops;
> +
> +	ctx = kunit_kmalloc_array(test, 3, sizeof(*ctx), GFP_KERNEL);
> +	KUNIT_ASSERT_NOT_NULL(test, ctx);
> +
> +	for (i = 0; i < 3; ++i) {
> +		ctx[i].test = test;
> +		init_completion(&ctx[i].started);
> +		init_completion(&ctx[i].enter);
> +
> +		if (i == 0) {
> +			ctx[i].thread = kthread_run(
> +				test_concurrent_unregister_supplier, ctx + i,
> +				"supplier%d", i);
> +		} else {
> +			init_completion(&ctx[i].entered);
> +			init_completion(&ctx[i].exit);
> +
> +			ctx[i].thread = kthread_run(
> +				test_concurrent_unregister_consumer, ctx + i,
> +				"consumer%d", i);
> +		}
> +		if (IS_ERR(ctx[i].thread)) {
> +			ret = PTR_ERR(ctx[i].thread);
> +			while (i--)
> +				kthread_stop_put(ctx[i].thread);
> +			KUNIT_ASSERT_EQ(test, ret, 0);
> +		}
> +		get_task_struct(ctx[i].thread);
> +
> +		wait_for_completion(&ctx[i].started);
> +	}
> +
> +	rtc->priv = &ctx[1];
> +	ctx[1].expected_ret = 0x12345678;
> +	/* consumer1 enters reset(). */
> +	KUNIT_EXPECT_EQ(test, rtc->reset_count, 0);
> +	complete(&ctx[1].enter);
> +	wait_for_completion(&ctx[1].entered);
> +	KUNIT_EXPECT_EQ(test, rtc->reset_count, 1);
> +
> +	/* supplier0 unregisters. */
> +	complete(&ctx[0].enter);
> +	ret = read_poll_timeout(reset_control_status, val, val == -ENODEV,
> +				1000, 100000, false, rtc->rstc);
> +	if (ret) {
> +		for (i = 2; i >= 0; --i)
> +			kthread_stop_put(ctx[i].thread);
> +		KUNIT_ASSERT_EQ(test, ret, 0);
> +	}
> +	/* supplier0 can't exit.  It's waiting for all consumers. */

This comment looks like an untested assertion. For all we know,
reset_controller_unregister() may have already returned by now.

How about signalling a completion "ctx->exited" after
reset_controller_unregister() returns, calling
wait_for_completion_timeout() here, and asserting it times out?


regards
Philipp