Re: [PATCH v2 1/1] lib/llist_kunit.c: add KUnit tests for llist

[Rae Moar]

On Tue, Sep 3, 2024 at 5:40 PM Artur Alves <arturacb@xxxxxxxxx> wrote:
>
> Add KUnit tests for the llist data structure. They test the vast
> majority of methods and macros defined in include/linux/llist.h.
>
> These are inspired by the existing tests for the 'list' doubly
> linked in lib/list-test.c [1]. Each test case (llist_test_x)
> tests the behaviour of the llist function/macro 'x'.
>
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/lib/list-test.c?h=v6.11-rc6
>
> Signed-off-by: Artur Alves <arturacb@xxxxxxxxx>

Hello!

Thanks for creating this new test! It looks really good and is passing
all the tests.

My main comment is that this patch is causing some checkpatch warnings:

  WARNING: Prefer a maximum 75 chars per line (possible unwrapped
commit description?)
  #13:
  [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/lib/list-test.c?h=v6.11-rc6

It's probably fine to ignore this warning as it is a link. But I might
remove the link because it is not absolutely necessary in this case.

  WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
  #58:
  new file mode 100644

  ERROR: that open brace { should be on the previous line
  #306: FILE: lib/llist_kunit.c:249:
  +static void llist_test_for_each_safe(struct kunit *test)
  +{

  ERROR: that open brace { should be on the previous line
  #325: FILE: lib/llist_kunit.c:268:
  +static void llist_test_for_each_entry(struct kunit *test)
  +{

  ERROR: that open brace { should be on the previous line
  #346: FILE: lib/llist_kunit.c:289:
  +static void llist_test_for_each_entry_safe(struct kunit *test)
  +{

These checkpatch errors are mistaken since the open brace should be
where it is. I believe this is getting picked up because of the
"for_each" in the test name. This was fixed for me by rewriting the
test names: from "llist_test_for_each_safe" -> to
"llist_test_safe_for_each", and so on for the other tests with errors.
Sorry it's a pain to change this but I think it is a better fix than
changing the checkpatch script.

> ---
>  lib/Kconfig.debug       |  11 ++
>  lib/tests/Makefile      |   1 +
>  lib/tests/llist_kunit.c | 361 ++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 373 insertions(+)
>  create mode 100644 lib/tests/llist_kunit.c
>
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index a30c03a66172..b2725daccc52 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -2813,6 +2813,17 @@ config USERCOPY_KUNIT_TEST
>           on the copy_to/from_user infrastructure, making sure basic
>           user/kernel boundary testing is working.
>
> +config LLIST_KUNIT_TEST
> +       tristate "KUnit tests for lib/llist" if !KUNIT_ALL_TESTS
> +       depends on KUNIT
> +       default KUNIT_ALL_TESTS
> +       help
> +         This option builds the "llist_kunit" test module that
> +         helps to verify the correctness of the functions and
> +         macros defined in (<linux/llist.h>).

Also, I think I would prefer if this description was a bit tweaked.
Saying it builds the "module" is confusing since this test might be
run built-in instead. So maybe something more similar to :

This builds the llist (lock-less list) KUnit test suite. It tests the
API and basic functionality of the macros and functions defined in
<linux/llish.h>.

> +
> +         If unsure, say N.
> +
>  config TEST_UDELAY
>         tristate "udelay test driver"
>         help
> diff --git a/lib/tests/Makefile b/lib/tests/Makefile
> index c6a14cc8663e..8d7c40a73110 100644
> --- a/lib/tests/Makefile
> +++ b/lib/tests/Makefile
> @@ -34,4 +34,5 @@ CFLAGS_stackinit_kunit.o += $(call cc-disable-warning, switch-unreachable)
>  obj-$(CONFIG_STACKINIT_KUNIT_TEST) += stackinit_kunit.o
>  obj-$(CONFIG_STRING_KUNIT_TEST) += string_kunit.o
>  obj-$(CONFIG_STRING_HELPERS_KUNIT_TEST) += string_helpers_kunit.o
> +obj-$(CONFIG_LLIST_KUNIT_TEST) += llist_kunit.o
>
> diff --git a/lib/tests/llist_kunit.c b/lib/tests/llist_kunit.c
> new file mode 100644
> index 000000000000..f273c0d175c7
> --- /dev/null
> +++ b/lib/tests/llist_kunit.c
> @@ -0,0 +1,361 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * KUnit test for the Kernel lock-less linked-list structure.
> + *
> + * Author: Artur Alves <arturacb@xxxxxxxxx>
> + */
> +
> +#include <kunit/test.h>
> +#include <linux/llist.h>
> +
> +#define ENTRIES_SIZE 3
> +
> +struct llist_test_struct {
> +       int data;
> +       struct llist_node node;
> +};
> +
> +static void llist_test_init_llist(struct kunit *test)
> +{
> +       /* test if the llist is correctly initialized */
> +       struct llist_head llist1 = LLIST_HEAD_INIT(llist1);
> +       LLIST_HEAD(llist2);
> +       struct llist_head llist3, *llist4, *llist5;
> +
> +       KUNIT_EXPECT_TRUE(test, llist_empty(&llist1));
> +
> +       KUNIT_EXPECT_TRUE(test, llist_empty(&llist2));
> +
> +       init_llist_head(&llist3);
> +       KUNIT_EXPECT_TRUE(test, llist_empty(&llist3));
> +
> +       llist4 = kzalloc(sizeof(*llist4), GFP_KERNEL | __GFP_NOFAIL);
> +       init_llist_head(llist4);
> +       KUNIT_EXPECT_TRUE(test, llist_empty(llist4));
> +       kfree(llist4);
> +
> +       llist5 = kmalloc(sizeof(*llist5), GFP_KERNEL | __GFP_NOFAIL);
> +       memset(llist5, 0xFF, sizeof(*llist5));
> +       init_llist_head(llist5);
> +       KUNIT_EXPECT_TRUE(test, llist_empty(llist5));
> +       kfree(llist5);
> +}
> +
> +static void llist_test_init_llist_node(struct kunit *test)
> +{
> +       struct llist_node a;
> +
> +       init_llist_node(&a);
> +
> +       KUNIT_EXPECT_PTR_EQ(test, a.next, &a);
> +}
> +
> +static void llist_test_llist_entry(struct kunit *test)
> +{
> +       struct llist_test_struct test_struct, *aux;
> +       struct llist_node *llist = &test_struct.node;
> +
> +       aux = llist_entry(llist, struct llist_test_struct, node);
> +       KUNIT_EXPECT_PTR_EQ(test, &test_struct, aux);
> +}
> +
> +static void llist_test_add(struct kunit *test)
> +{
> +       struct llist_node a, b;
> +       LLIST_HEAD(llist);
> +
> +       init_llist_node(&a);
> +       init_llist_node(&b);
> +
> +       /* The first assertion must be true, given that llist is empty */
> +       KUNIT_EXPECT_TRUE(test, llist_add(&a, &llist));
> +       KUNIT_EXPECT_FALSE(test, llist_add(&b, &llist));
> +
> +       /* Should be [List] -> b -> a */
> +       KUNIT_EXPECT_PTR_EQ(test, llist.first, &b);
> +       KUNIT_EXPECT_PTR_EQ(test, b.next, &a);
> +}
> +
> +static void llist_test_add_batch(struct kunit *test)
> +{
> +       struct llist_node a, b, c;
> +       LLIST_HEAD(llist);
> +       LLIST_HEAD(llist2);
> +
> +       init_llist_node(&a);
> +       init_llist_node(&b);
> +       init_llist_node(&c);
> +
> +       llist_add(&a, &llist2);
> +       llist_add(&b, &llist2);
> +       llist_add(&c, &llist2);
> +
> +       /* This assertion must be true, given that llist is empty */
> +       KUNIT_EXPECT_TRUE(test, llist_add_batch(&c, &a, &llist));
> +
> +       /* should be [List] -> c -> b -> a */
> +       KUNIT_EXPECT_PTR_EQ(test, llist.first, &c);
> +       KUNIT_EXPECT_PTR_EQ(test, c.next, &b);
> +       KUNIT_EXPECT_PTR_EQ(test, b.next, &a);
> +}
> +
> +static void llist_test_llist_next(struct kunit *test)
> +{
> +       struct llist_node a, b;
> +       LLIST_HEAD(llist);
> +
> +       init_llist_node(&a);
> +       init_llist_node(&b);
> +
> +       llist_add(&a, &llist);
> +       llist_add(&b, &llist);
> +
> +       /* should be [List] -> b -> a */
> +       KUNIT_EXPECT_PTR_EQ(test, llist_next(&b), &a);
> +       KUNIT_EXPECT_NULL(test, llist_next(&a));
> +}
> +
> +static void llist_test_empty_llist(struct kunit *test)
> +{
> +       struct llist_head llist = LLIST_HEAD_INIT(llist);
> +       struct llist_node a;
> +
> +       KUNIT_EXPECT_TRUE(test, llist_empty(&llist));
> +
> +       llist_add(&a, &llist);
> +
> +       KUNIT_EXPECT_FALSE(test, llist_empty(&llist));
> +}
> +
> +static void llist_test_llist_on_list(struct kunit *test)
> +{
> +       struct llist_node a, b;
> +       LLIST_HEAD(llist);
> +
> +       init_llist_node(&a);
> +       init_llist_node(&b);
> +
> +       llist_add(&a, &llist);
> +
> +       /* should be [List] -> a */
> +       KUNIT_EXPECT_TRUE(test, llist_on_list(&a));
> +       KUNIT_EXPECT_FALSE(test, llist_on_list(&b));
> +}
> +
> +static void llist_test_del_first(struct kunit *test)
> +{
> +       struct llist_node a, b, *c;
> +       LLIST_HEAD(llist);
> +
> +       llist_add(&a, &llist);
> +       llist_add(&b, &llist);
> +
> +       /* before: [List] -> b -> a */
> +       c = llist_del_first(&llist);
> +
> +       /* should be [List] -> a */
> +       KUNIT_EXPECT_PTR_EQ(test, llist.first, &a);
> +
> +       /* del must return a pointer to llist_node b
> +        * the returned pointer must be marked on list
> +        */
> +       KUNIT_EXPECT_PTR_EQ(test, c, &b);
> +       KUNIT_EXPECT_TRUE(test, llist_on_list(c));
> +}
> +
> +static void llist_test_del_first_init(struct kunit *test)
> +{
> +       struct llist_node a, *b;
> +       LLIST_HEAD(llist);
> +
> +       llist_add(&a, &llist);
> +
> +       b = llist_del_first_init(&llist);
> +
> +       /* should be [List] */
> +       KUNIT_EXPECT_TRUE(test, llist_empty(&llist));
> +
> +       /* the returned pointer must be marked out of the list */
> +       KUNIT_EXPECT_FALSE(test, llist_on_list(b));
> +}
> +
> +static void llist_test_del_first_this(struct kunit *test)
> +{
> +       struct llist_node a, b;
> +       LLIST_HEAD(llist);
> +
> +       llist_add(&a, &llist);
> +       llist_add(&b, &llist);
> +
> +       llist_del_first_this(&llist, &a);
> +
> +       /* before: [List] -> b -> a */
> +
> +       // should remove only if is the first node in the llist
> +       KUNIT_EXPECT_FALSE(test, llist_del_first_this(&llist, &a));
> +
> +       KUNIT_EXPECT_TRUE(test, llist_del_first_this(&llist, &b));
> +
> +       /* should be [List] -> a */
> +       KUNIT_EXPECT_PTR_EQ(test, llist.first, &a);
> +}
> +
> +static void llist_test_del_all(struct kunit *test)
> +{
> +       struct llist_node a, b;
> +       LLIST_HEAD(llist);
> +       LLIST_HEAD(empty_llist);
> +
> +       llist_add(&a, &llist);
> +       llist_add(&b, &llist);
> +
> +       /* deleting from a empty llist should return NULL */
> +       KUNIT_EXPECT_NULL(test, llist_del_all(&empty_llist));
> +
> +       llist_del_all(&llist);
> +
> +       KUNIT_EXPECT_TRUE(test, llist_empty(&llist));
> +}
> +
> +static void llist_test_for_each(struct kunit *test)
> +{
> +       struct llist_node entries[ENTRIES_SIZE] = { 0 };
> +       struct llist_node *pos, *deleted_nodes;
> +       LLIST_HEAD(llist);
> +       int i = 0;
> +
> +       for (int i = ENTRIES_SIZE - 1; i >= 0; i--)
> +               llist_add(&entries[i], &llist);
> +
> +       /* before [List] -> entries[0] -> ... -> entries[ENTRIES_SIZE - 1] */
> +       llist_for_each(pos, llist.first) {
> +               KUNIT_EXPECT_PTR_EQ(test, pos, &entries[i++]);
> +       }
> +
> +       KUNIT_EXPECT_EQ(test, ENTRIES_SIZE, i);
> +
> +       i = 0;

This is super nitpicky but I think I would prefer if you set two
variables to zero at the beginning rather than reusing "i". So: int i
= 0, j = 0;

> +
> +       /* traversing deleted nodes */
> +       deleted_nodes = llist_del_all(&llist);
> +
> +       llist_for_each(pos, deleted_nodes) {
> +               KUNIT_EXPECT_PTR_EQ(test, pos, &entries[i++]);
> +       }
> +
> +       KUNIT_EXPECT_EQ(test, ENTRIES_SIZE, i);
> +}
> +
> +static void llist_test_for_each_safe(struct kunit *test)
> +{
> +       struct llist_node entries[ENTRIES_SIZE] = { 0 };

I'm not sure if it is necessary to initialize this to be zeros.

> +       struct llist_node *pos, *n;
> +       LLIST_HEAD(llist);
> +       int i = 0;
> +
> +       for (int i = ENTRIES_SIZE - 1; i >= 0; i--)
> +               llist_add(&entries[i], &llist);
> +
> +       llist_for_each_safe(pos, n, llist.first) {
> +               KUNIT_EXPECT_PTR_EQ(test, pos, &entries[i++]);
> +               llist_del_first(&llist);
> +       }
> +
> +       KUNIT_EXPECT_EQ(test, ENTRIES_SIZE, i);
> +       KUNIT_EXPECT_TRUE(test, llist_empty(&llist));
> +}
> +
> +static void llist_test_for_each_entry(struct kunit *test)
> +{
> +       struct llist_test_struct entries[ENTRIES_SIZE], *pos;
> +       LLIST_HEAD(llist);
> +       int i = 0;
> +
> +       for (int i = ENTRIES_SIZE - 1; i >= 0; --i) {
> +               entries[i].data = i;
> +               llist_add(&entries[i].node, &llist);
> +       }
> +
> +       i = 0;
> +
> +       llist_for_each_entry(pos, llist.first, node) {
> +               KUNIT_EXPECT_EQ(test, pos->data, i);
> +               i++;
> +       }
> +
> +       KUNIT_EXPECT_EQ(test, ENTRIES_SIZE, i);
> +}
> +
> +static void llist_test_for_each_entry_safe(struct kunit *test)
> +{
> +       struct llist_test_struct entries[ENTRIES_SIZE], *pos, *n;
> +       LLIST_HEAD(llist);
> +       int i = 0;
> +
> +       for (int i = ENTRIES_SIZE - 1; i >= 0; --i) {
> +               entries[i].data = i;
> +               llist_add(&entries[i].node, &llist);
> +       }
> +
> +       i = 0;
> +
> +       llist_for_each_entry_safe(pos, n, llist.first, node) {
> +               KUNIT_EXPECT_EQ(test, pos->data, i++);
> +               llist_del_first(&llist);
> +       }
> +
> +       KUNIT_EXPECT_EQ(test, ENTRIES_SIZE, i);
> +       KUNIT_EXPECT_TRUE(test, llist_empty(&llist));
> +}
> +
> +static void llist_test_reverse_order(struct kunit *test)
> +{
> +       struct llist_node entries[3], *pos, *reversed_llist;

Rather than using the "3" here I would prefer using the ENTRIES_SIZE.

> +       LLIST_HEAD(llist);
> +       int i = 0;
> +
> +       llist_add(&entries[0], &llist);
> +       llist_add(&entries[1], &llist);
> +       llist_add(&entries[2], &llist);
> +
> +       /* before [List] -> entries[2] -> entries[1] -> entries[0] */
> +       reversed_llist = llist_reverse_order(llist_del_first(&llist));
> +
> +       /* should be [List] -> entries[0] -> entries[1] -> entrires[2] */

Small typo in this comment: "entries"

> +       llist_for_each(pos, reversed_llist) {
> +               KUNIT_EXPECT_PTR_EQ(test, pos, &entries[i++]);
> +       }
> +
> +       KUNIT_EXPECT_EQ(test, 3, i);

Same here with the use of the "3".

> +}
> +
> +static struct kunit_case llist_test_cases[] = {
> +       KUNIT_CASE(llist_test_init_llist),
> +       KUNIT_CASE(llist_test_init_llist_node),
> +       KUNIT_CASE(llist_test_llist_entry),
> +       KUNIT_CASE(llist_test_add),
> +       KUNIT_CASE(llist_test_add_batch),
> +       KUNIT_CASE(llist_test_llist_next),
> +       KUNIT_CASE(llist_test_empty_llist),
> +       KUNIT_CASE(llist_test_llist_on_list),
> +       KUNIT_CASE(llist_test_del_first),
> +       KUNIT_CASE(llist_test_del_first_init),
> +       KUNIT_CASE(llist_test_del_first_this),
> +       KUNIT_CASE(llist_test_del_all),
> +       KUNIT_CASE(llist_test_for_each),
> +       KUNIT_CASE(llist_test_for_each_safe),
> +       KUNIT_CASE(llist_test_for_each_entry),
> +       KUNIT_CASE(llist_test_for_each_entry_safe),
> +       KUNIT_CASE(llist_test_reverse_order),
> +       {}
> +};
> +
> +static struct kunit_suite llist_test_suite = {
> +       .name = "llist",
> +       .test_cases = llist_test_cases,
> +};
> +
> +kunit_test_suite(llist_test_suite);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("KUnit tests for the llist data structure.");
> --
> 2.46.0
>
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