[PATCH v2 4/6] lib/tests/kfifo_kunit.c: add tests for the kfifo structure

Kees Cook
2025-02-11T00:31:36Z

From: Diego Vieira <diego.daniel.professional@gmail.com>

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 doubly
linked list in lib/tests/list-test.c (previously at lib/list-test.c) [1].

Note that this patch depends on the patch that moves the KUnit tests on
lib/ into lib/tests/ [2].

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/lib/list-test.c?h=v6.11-rc6
[2] https://lore.kernel.org/all/20240720181025.work.002-kees@kernel.org/

Signed-off-by: Diego Vieira <diego.daniel.professional@gmail.com>
Reviewed-by: David Gow <davidgow@google.com>
Reviewed-by: Rae Moar <rmoar@google.com>
Link: https://lore.kernel.org/r/20241202075545.3648096-5-davidgow@google.com
Signed-off-by: Kees Cook <kees@kernel.org>
---
lib/Kconfig.debug | 14 +++
lib/tests/Makefile | 1 +
lib/tests/kfifo_kunit.c | 224 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 239 insertions(+)
create mode 100644 lib/tests/kfifo_kunit.c

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index f30929ed1a84..86ddf568cbca 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2691,6 +2691,20 @@ 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/tests/Makefile b/lib/tests/Makefile
index c7b5170359c1..8696d778d92f 100644
--- a/lib/tests/Makefile
+++ b/lib/tests/Makefile
@@ -23,6 +23,7 @@ obj-$(CONFIG_TEST_IOV_ITER) += kunit_iov_iter.o
obj-$(CONFIG_IS_SIGNED_TYPE_KUNIT_TEST) += is_signed_type_kunit.o
obj-$(CONFIG_KPROBES_SANITY_TEST) += test_kprobes.o
obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o
+obj-$(CONFIG_KFIFO_KUNIT_TEST) += kfifo_kunit.o
obj-$(CONFIG_TEST_LIST_SORT) += test_list_sort.o
obj-$(CONFIG_LINEAR_RANGES_TEST) += test_linear_ranges.o
obj-$(CONFIG_MEMCPY_KUNIT_TEST) += memcpy_kunit.o
diff --git a/lib/tests/kfifo_kunit.c b/lib/tests/kfifo_kunit.c
new file mode 100644
index 000000000000..a85eedc3195a
--- /dev/null
+++ b/lib/tests/kfifo_kunit.c
@@ -0,0 +1,224 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit test for the generic kernel FIFO implementation.
+ *
+ * Copyright (C) 2024 Diego Vieira <diego.daniel.professional@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");
+MODULE_AUTHOR("Diego Vieira <diego.daniel.professional@gmail.com>");
+MODULE_DESCRIPTION("KUnit test for the kernel FIFO");
--
2.34.1