[PATCH 0/1] Add KUnit tests for llist

[Artur Alves]

Hi all,

This is part of a hackathon organized by LKCAMP[1], focused on writing
tests using KUnit. We reached out a while ago asking for advice on what would
be a useful contribution[2] and ended up choosing data structures that did
not yet have tests.

This patch adds tests for the llist data structure, defined in
include/linux/llist.h, and is inspired by the KUnit tests for the doubly
linked list in lib/list-test.c[3].

[1] https://lkcamp.dev/about/
[2] https://lore.kernel.org/all/Zktnt7rjKryTh9-N@arch/
[3] https://elixir.bootlin.com/linux/latest/source/lib/list-test.c

Artur Alves (1):
lib/llist_kunit.c: add KUnit tests for llist

lib/Kconfig.debug | 11 ++
lib/Makefile | 1 +
lib/llist_kunit.c | 360 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 372 insertions(+)
create mode 100644 lib/llist_kunit.c

--
2.45.2

[Artur Alves]

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

Signed-off-by: Artur Alves <artu...@gmail.com>
---

lib/Kconfig.debug | 11 ++
lib/Makefile | 1 +
lib/llist_kunit.c | 360 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 372 insertions(+)
create mode 100644 lib/llist_kunit.c

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 561e346f5cb0..f58649c6cce2 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2811,6 +2811,17 @@ 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>).
+
+ If unsure, say N.
+
config TEST_UDELAY
tristate "udelay test driver"
help
diff --git a/lib/Makefile b/lib/Makefile
index 322bb127b4dc..da5ebe56c33c 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -370,6 +370,7 @@ CFLAGS_bitfield_kunit.o := $(DISABLE_STRUCTLEAK_PLUGIN)
obj-$(CONFIG_BITFIELD_KUNIT) += bitfield_kunit.o
obj-$(CONFIG_CHECKSUM_KUNIT) += checksum_kunit.o
obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o
+obj-$(CONFIG_LLIST_KUNIT_TEST) += llist_kunit.o
obj-$(CONFIG_HASHTABLE_KUNIT_TEST) += hashtable_test.o
obj-$(CONFIG_LINEAR_RANGES_TEST) += test_linear_ranges.o
obj-$(CONFIG_BITS_TEST) += test_bits.o
diff --git a/lib/llist_kunit.c b/lib/llist_kunit.c
new file mode 100644
index 000000000000..7ffe2e2428a3
--- /dev/null
+++ b/lib/llist_kunit.c
@@ -0,0 +1,360 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit test for the Kernel lock-less linked-list structure.
+ *
+ * Author: Artur Alves <artu...@gmail.com>
+ */
+
+#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;
+
+ /* 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 };
+ 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;
+ 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] */
+ llist_for_each(pos, reversed_llist) {
+ KUNIT_EXPECT_PTR_EQ(test, pos, &entries[i++]);
+ }
+
+ KUNIT_EXPECT_EQ(test, 3, i);
+}
+
+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 v2");
--
2.45.2

[Jeff Johnson]

On 7/21/24 16:43, Artur Alves 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
>
> Signed-off-by: Artur Alves <artu...@gmail.com>
> ---
> lib/Kconfig.debug | 11 ++
> lib/Makefile | 1 +
> lib/llist_kunit.c | 360 ++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 372 insertions(+)
> create mode 100644 lib/llist_kunit.c

...

> +MODULE_LICENSE("GPL v2");

Since commit 1fffe7a34c89 ("script: modpost: emit a warning when the
description is missing") a module without a MODULE_DESCRIPTION() will
result in a warning with make W=1.

Multiple developers, including myself, have been fixing the existing
warnings for 6.11 so please don't introduce a new one :)

/jeff

[Artur Alves]

Hi Jeff,

I was unaware of this commit, I'm going to fix this issue to ensure no
warnings are introduced.

Now I'm also aware of two patches that reorganize KUnit tests ([1], [2]).
I'll take these into account for the revised version.

Thanks for your reply.

Artur Alves

[1] https://lore.kernel.org/linux-kselftest/20240720181025...@kernel.org/
[2] https://lore.kernel.org/linux-kselftest/20240724201354...@kernel.org/