[PATCH 0/1] Add KUnit tests for kfifo

[Diego Vieira]

From: diegodvv <diego.daniel...@gmail.com>

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 kfifo data structure, defined in
include/linux/kfifo.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

Diego Vieira (1):
lib/kfifo-test.c: add tests for the kfifo structure

lib/Kconfig.debug | 14 +++
lib/Makefile | 1 +
lib/kfifo-test.c | 222 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 237 insertions(+)
create mode 100644 lib/kfifo-test.c

--
2.34.1

[Diego Vieira]

Add KUnit tests for the kfifo data structure.
They test the vast majority of macros defined in the kfifo
header (include/linux/kfifo.h).

These are inspired by the existing tests for the 'list' doubly
linked in lib/list-test.c [1].

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/lib/list-test.c

Signed-off-by: Diego Vieira <diego.daniel...@gmail.com>
---

lib/Kconfig.debug | 14 +++
lib/Makefile | 1 +
lib/kfifo-test.c | 222 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 237 insertions(+)
create mode 100644 lib/kfifo-test.c

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 59b6765d86b8..d7a4b996d731 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2646,6 +2646,20 @@ config SYSCTL_KUNIT_TEST

If unsure, say N.

+config KFIFO_KUNIT_TEST
+ tristate "KUnit Test for the generic kernel FIFO implementation" if !KUNIT_ALL_TESTS
+ depends on KUNIT
+ default KUNIT_ALL_TESTS
+ help
+ This builds the generic FIFO implementation KUnit test suite.
+ It tests that the API and basic functionality of the kfifo type
+ and associated macros.
+
+ For more information on KUnit and unit tests in general please refer
+ to the KUnit documentation in Documentation/dev-tools/kunit/.
+
+ If unsure, say N.
+
config LIST_KUNIT_TEST
tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
depends on KUNIT
diff --git a/lib/Makefile b/lib/Makefile
index 3b1769045651..db8dc4cb1b47 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -370,6 +370,7 @@ obj-$(CONFIG_PLDMFW) += pldmfw/
CFLAGS_bitfield_kunit.o := $(DISABLE_STRUCTLEAK_PLUGIN)
obj-$(CONFIG_BITFIELD_KUNIT) += bitfield_kunit.o
obj-$(CONFIG_CHECKSUM_KUNIT) += checksum_kunit.o
+obj-$(CONFIG_KFIFO_KUNIT_TEST) += kfifo-test.o
obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o
obj-$(CONFIG_HASHTABLE_KUNIT_TEST) += hashtable_test.o
obj-$(CONFIG_LINEAR_RANGES_TEST) += test_linear_ranges.o
diff --git a/lib/kfifo-test.c b/lib/kfifo-test.c
new file mode 100644
index 000000000000..5ea41d22b6b5
--- /dev/null
+++ b/lib/kfifo-test.c
@@ -0,0 +1,222 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit test for the generic kernel FIFO implementation.
+ *
+ * Copyright (C) 2024 Diego Vieira <diego.daniel...@gmail.com>
+ */
+#include <kunit/test.h>
+
+#include <linux/kfifo.h>
+
+#define KFIFO_SIZE 32
+#define N_ELEMENTS 5
+
+static void kfifo_test_reset_should_clear_the_fifo(struct kunit *test)
+{
+ DEFINE_KFIFO(my_fifo, u8, KFIFO_SIZE);
+
+ kfifo_put(&my_fifo, 1);
+ kfifo_put(&my_fifo, 2);
+ kfifo_put(&my_fifo, 3);
+ KUNIT_EXPECT_EQ(test, kfifo_len(&my_fifo), 3);
+
+ kfifo_reset(&my_fifo);
+
+ KUNIT_EXPECT_EQ(test, kfifo_len(&my_fifo), 0);
+ KUNIT_EXPECT_TRUE(test, kfifo_is_empty(&my_fifo));
+}
+
+static void kfifo_test_define_should_define_an_empty_fifo(struct kunit *test)
+{
+ DEFINE_KFIFO(my_fifo, u8, KFIFO_SIZE);
+
+ KUNIT_EXPECT_TRUE(test, kfifo_initialized(&my_fifo));
+ KUNIT_EXPECT_TRUE(test, kfifo_is_empty(&my_fifo));
+ KUNIT_EXPECT_EQ(test, kfifo_len(&my_fifo), 0);
+}
+
+static void kfifo_test_len_should_ret_n_of_stored_elements(struct kunit *test)
+{
+ u8 buffer1[N_ELEMENTS];
+
+ for (int i = 0; i < N_ELEMENTS; i++)
+ buffer1[i] = i + 1;
+
+ DEFINE_KFIFO(my_fifo, u8, KFIFO_SIZE);
+
+ KUNIT_EXPECT_EQ(test, kfifo_len(&my_fifo), 0);
+
+ kfifo_in(&my_fifo, buffer1, N_ELEMENTS);
+ KUNIT_EXPECT_EQ(test, kfifo_len(&my_fifo), N_ELEMENTS);
+
+ kfifo_in(&my_fifo, buffer1, N_ELEMENTS);
+ KUNIT_EXPECT_EQ(test, kfifo_len(&my_fifo), N_ELEMENTS * 2);
+
+ kfifo_reset(&my_fifo);
+ KUNIT_EXPECT_EQ(test, kfifo_len(&my_fifo), 0);
+}
+
+static void kfifo_test_put_should_insert_and_get_should_pop(struct kunit *test)
+{
+ u8 out_data = 0;
+ int processed_elements;
+ u8 elements[] = { 3, 5, 11 };
+
+ DEFINE_KFIFO(my_fifo, u8, KFIFO_SIZE);
+
+ // If the fifo is empty, get returns 0
+ processed_elements = kfifo_get(&my_fifo, &out_data);
+ KUNIT_EXPECT_EQ(test, processed_elements, 0);
+ KUNIT_EXPECT_EQ(test, out_data, 0);
+
+ for (int i = 0; i < 3; i++)
+ kfifo_put(&my_fifo, elements[i]);
+
+ for (int i = 0; i < 3; i++) {
+ processed_elements = kfifo_get(&my_fifo, &out_data);
+ KUNIT_EXPECT_EQ(test, processed_elements, 1);
+ KUNIT_EXPECT_EQ(test, out_data, elements[i]);
+ }
+}
+
+static void kfifo_test_in_should_insert_multiple_elements(struct kunit *test)
+{
+ u8 in_buffer[] = { 11, 25, 65 };
+ u8 out_data;
+ int processed_elements;
+
+ DEFINE_KFIFO(my_fifo, u8, KFIFO_SIZE);
+
+ kfifo_in(&my_fifo, in_buffer, 3);
+
+ for (int i = 0; i < 3; i++) {
+ processed_elements = kfifo_get(&my_fifo, &out_data);
+ KUNIT_EXPECT_EQ(test, processed_elements, 1);
+ KUNIT_EXPECT_EQ(test, out_data, in_buffer[i]);
+ }
+}
+
+static void kfifo_test_out_should_pop_multiple_elements(struct kunit *test)
+{
+ u8 in_buffer[] = { 11, 25, 65 };
+ u8 out_buffer[3];
+ int copied_elements;
+
+ DEFINE_KFIFO(my_fifo, u8, KFIFO_SIZE);
+
+ for (int i = 0; i < 3; i++)
+ kfifo_put(&my_fifo, in_buffer[i]);
+
+ copied_elements = kfifo_out(&my_fifo, out_buffer, 3);
+ KUNIT_EXPECT_EQ(test, copied_elements, 3);
+
+ for (int i = 0; i < 3; i++)
+ KUNIT_EXPECT_EQ(test, out_buffer[i], in_buffer[i]);
+ KUNIT_EXPECT_TRUE(test, kfifo_is_empty(&my_fifo));
+}
+
+static void kfifo_test_dec_init_should_define_an_empty_fifo(struct kunit *test)
+{
+ DECLARE_KFIFO(my_fifo, u8, KFIFO_SIZE);
+
+ INIT_KFIFO(my_fifo);
+
+ // my_fifo is a struct with an inplace buffer
+ KUNIT_EXPECT_FALSE(test, __is_kfifo_ptr(&my_fifo));
+
+ KUNIT_EXPECT_TRUE(test, kfifo_initialized(&my_fifo));
+}
+
+static void kfifo_test_define_should_equal_declare_init(struct kunit *test)
+{
+ // declare a variable my_fifo of type struct kfifo of u8
+ DECLARE_KFIFO(my_fifo1, u8, KFIFO_SIZE);
+ // initialize the my_fifo variable
+ INIT_KFIFO(my_fifo1);
+
+ // DEFINE_KFIFO declares the variable with the initial value
+ // essentially the same as calling DECLARE_KFIFO and INIT_KFIFO
+ DEFINE_KFIFO(my_fifo2, u8, KFIFO_SIZE);
+
+ // my_fifo1 and my_fifo2 have the same size
+ KUNIT_EXPECT_EQ(test, sizeof(my_fifo1), sizeof(my_fifo2));
+ KUNIT_EXPECT_EQ(test, kfifo_initialized(&my_fifo1),
+ kfifo_initialized(&my_fifo2));
+ KUNIT_EXPECT_EQ(test, kfifo_is_empty(&my_fifo1),
+ kfifo_is_empty(&my_fifo2));
+}
+
+static void kfifo_test_alloc_should_initiliaze_a_ptr_fifo(struct kunit *test)
+{
+ int ret;
+ DECLARE_KFIFO_PTR(my_fifo, u8);
+
+ INIT_KFIFO(my_fifo);
+
+ // kfifo_initialized returns false signaling the buffer pointer is NULL
+ KUNIT_EXPECT_FALSE(test, kfifo_initialized(&my_fifo));
+
+ // kfifo_alloc allocates the buffer
+ ret = kfifo_alloc(&my_fifo, KFIFO_SIZE, GFP_KERNEL);
+ KUNIT_EXPECT_EQ_MSG(test, ret, 0, "Memory allocation should succeed");
+ KUNIT_EXPECT_TRUE(test, kfifo_initialized(&my_fifo));
+
+ // kfifo_free frees the buffer
+ kfifo_free(&my_fifo);
+}
+
+static void kfifo_test_peek_should_not_remove_elements(struct kunit *test)
+{
+ u8 out_data;
+ int processed_elements;
+
+ DEFINE_KFIFO(my_fifo, u8, KFIFO_SIZE);
+
+ // If the fifo is empty, peek returns 0
+ processed_elements = kfifo_peek(&my_fifo, &out_data);
+ KUNIT_EXPECT_EQ(test, processed_elements, 0);
+
+ kfifo_put(&my_fifo, 3);
+ kfifo_put(&my_fifo, 5);
+ kfifo_put(&my_fifo, 11);
+
+ KUNIT_EXPECT_EQ(test, kfifo_len(&my_fifo), 3);
+
+ processed_elements = kfifo_peek(&my_fifo, &out_data);
+ KUNIT_EXPECT_EQ(test, processed_elements, 1);
+ KUNIT_EXPECT_EQ(test, out_data, 3);
+
+ KUNIT_EXPECT_EQ(test, kfifo_len(&my_fifo), 3);
+
+ // Using peek doesn't remove the element
+ // so the read element and the fifo length
+ // remains the same
+ processed_elements = kfifo_peek(&my_fifo, &out_data);
+ KUNIT_EXPECT_EQ(test, processed_elements, 1);
+ KUNIT_EXPECT_EQ(test, out_data, 3);
+
+ KUNIT_EXPECT_EQ(test, kfifo_len(&my_fifo), 3);
+}
+
+static struct kunit_case kfifo_test_cases[] = {
+ KUNIT_CASE(kfifo_test_reset_should_clear_the_fifo),
+ KUNIT_CASE(kfifo_test_define_should_define_an_empty_fifo),
+ KUNIT_CASE(kfifo_test_len_should_ret_n_of_stored_elements),
+ KUNIT_CASE(kfifo_test_put_should_insert_and_get_should_pop),
+ KUNIT_CASE(kfifo_test_in_should_insert_multiple_elements),
+ KUNIT_CASE(kfifo_test_out_should_pop_multiple_elements),
+ KUNIT_CASE(kfifo_test_dec_init_should_define_an_empty_fifo),
+ KUNIT_CASE(kfifo_test_define_should_equal_declare_init),
+ KUNIT_CASE(kfifo_test_alloc_should_initiliaze_a_ptr_fifo),
+ KUNIT_CASE(kfifo_test_peek_should_not_remove_elements),
+ {},
+};
+
+static struct kunit_suite kfifo_test_module = {
+ .name = "kfifo",
+ .test_cases = kfifo_test_cases,
+};
+
+kunit_test_suites(&kfifo_test_module);
+
+MODULE_LICENSE("GPL");
--
2.34.1

[Jeff Johnson]

On 7/21/24 17:18, Diego Vieira wrote:
> Add KUnit tests for the kfifo data structure.
> They test the vast majority of macros defined in the kfifo
> header (include/linux/kfifo.h).
>
> These are inspired by the existing tests for the 'list' doubly
> linked in lib/list-test.c [1].
>
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/lib/list-test.c
>
> Signed-off-by: Diego Vieira <diego.daniel...@gmail.com>
> ---
> lib/Kconfig.debug | 14 +++
> lib/Makefile | 1 +
> lib/kfifo-test.c | 222 ++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 237 insertions(+)
> create mode 100644 lib/kfifo-test.c

...
> +MODULE_LICENSE("GPL");

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