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SubjectRe: [PATCH v9 02/18] kunit: test: add test resource management API
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Quoting Brendan Higgins (2019-07-12 01:17:28)
> diff --git a/kunit/test.c b/kunit/test.c
> index 571e4c65deb5c..f165c9d8e10b0 100644
> --- a/kunit/test.c
> +++ b/kunit/test.c
> @@ -171,6 +175,96 @@ int kunit_run_tests(struct kunit_suite *suite)
> return 0;
> }
>
> +struct kunit_resource *kunit_alloc_resource(struct kunit *test,
> + kunit_resource_init_t init,
> + kunit_resource_free_t free,
> + void *context)
> +{
> + struct kunit_resource *res;
> + int ret;
> +
> + res = kzalloc(sizeof(*res), GFP_KERNEL);

This uses GFP_KERNEL.

> + if (!res)
> + return NULL;
> +
> + ret = init(res, context);
> + if (ret)
> + return NULL;
> +
> + res->free = free;
> + mutex_lock(&test->lock);

And this can sleep.

> + list_add_tail(&res->node, &test->resources);
> + mutex_unlock(&test->lock);
> +
> + return res;
> +}
> +
> +void kunit_free_resource(struct kunit *test, struct kunit_resource *res)

Should probably add a note that we assume the test lock is held here, or
even add a lockdep_assert_held(&test->lock) into the function to
document that and assert it at the same time.

> +{
> + res->free(res);
> + list_del(&res->node);
> + kfree(res);
> +}
> +
> +struct kunit_kmalloc_params {
> + size_t size;
> + gfp_t gfp;
> +};
> +
> +static int kunit_kmalloc_init(struct kunit_resource *res, void *context)
> +{
> + struct kunit_kmalloc_params *params = context;
> +
> + res->allocation = kmalloc(params->size, params->gfp);
> + if (!res->allocation)
> + return -ENOMEM;
> +
> + return 0;
> +}
> +
> +static void kunit_kmalloc_free(struct kunit_resource *res)
> +{
> + kfree(res->allocation);
> +}
> +
> +void *kunit_kmalloc(struct kunit *test, size_t size, gfp_t gfp)
> +{
> + struct kunit_kmalloc_params params;
> + struct kunit_resource *res;
> +
> + params.size = size;
> + params.gfp = gfp;
> +
> + res = kunit_alloc_resource(test,

This calls that sleeping function above...

> + kunit_kmalloc_init,
> + kunit_kmalloc_free,
> + &params);

but this passes a GFP flags parameter through to the
kunit_kmalloc_init() function. How is this going to work if some code
uses GFP_ATOMIC, but then we try to allocate and sleep in
kunit_alloc_resource() with GFP_KERNEL?

One solution would be to piggyback on all the existing devres allocation
logic we already have and make each struct kunit a device that we pass
into the devres functions. A far simpler solution would be to just
copy/paste what devres does and use a spinlock and an allocation
function that takes GFP flags.

> +
> + if (res)
> + return res->allocation;
> +
> + return NULL;
> +}

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