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

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@gmail.com>
---
 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

On 9/5/24 5:51 PM, Rae Moar wrote:
> On Tue, Sep 3, 2024 at 5:40 PM Artur Alves <arturacb@gmail.com> 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@gmail.com>
> 
> 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@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;
> 
> 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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Hi!

Thanks for the reply! I'm going to address these issues ASAP :)