[Linux-kernel-mentees] [PATCH v2] lib: Convert test_printf.c to KUnit

Arpitha Raghunandan 98.arpi at gmail.com
Thu Oct 22 15:13:49 UTC 2020


Convert test lib/test_printf.c to KUnit. More information about
KUnit can be found at:
https://www.kernel.org/doc/html/latest/dev-tools/kunit/index.html.
KUnit provides a common framework for unit tests in the kernel.
KUnit and kselftest are standardizing around KTAP, converting this
test to KUnit makes this test output in KTAP which we are trying to
make the standard test result format for the kernel. More about
the KTAP format can be found at:
https://lore.kernel.org/linux-kselftest/CY4PR13MB1175B804E31E502221BC8163FD830@CY4PR13MB1175.namprd13.prod.outlook.com/.
I ran both the original and converted tests as is to produce the
output for success of the test in the two cases. I also ran these
tests with a small modification to show the difference in the output
for failure of the test in both cases. The modification I made is:
- test("127.000.000.001|127.0.0.1", "%pi4|%pI4", &sa.sin_addr, &sa.sin_addr);
+ test("127-000.000.001|127.0.0.1", "%pi4|%pI4", &sa.sin_addr, &sa.sin_addr);

Original test success:
[    0.591262] test_printf: loaded.
[    0.591409] test_printf: all 388 tests passed

Original test failure:
[    0.619345] test_printf: loaded.
[    0.619394] test_printf: vsnprintf(buf, 256, "%piS|%pIS", ...)
wrote '127.000.000.001|127.0.0.1', expected
'127-000.000.001|127.0.0.1'
[    0.619395] test_printf: vsnprintf(buf, 25, "%piS|%pIS", ...) wrote
'127.000.000.001|127.0.0.', expected '127-000.000.001|127.0.0.'
[    0.619396] test_printf: kvasprintf(..., "%piS|%pIS", ...) returned
'127.000.000.001|127.0.0.1', expected '127-000.000.001|127.0.0.1'
[    0.619495] test_printf: failed 3 out of 388 tests

Converted test success:
    # Subtest: printf-kunit-test
    1..1
    ok 1 - selftest
ok 1 - printf-kunit-test

Converted test failure:
    # Subtest: printf-kunit-test
    1..1
    # selftest: EXPECTATION FAILED at lib/printf_kunit.c:82
vsnprintf(buf, 256, "%pi4|%pI4", ...) wrote
'127.000.000.001|127.0.0.1', expected '127-000.000.001|127.0.0.1'
    # selftest: EXPECTATION FAILED at lib/printf_kunit.c:82
vsnprintf(buf, 5, "%pi4|%pI4", ...) wrote '127.', expected '127-'
    # selftest: EXPECTATION FAILED at lib/printf_kunit.c:118
kvasprintf(..., "%pi4|%pI4", ...) returned
'127.000.000.001|127.0.0.1', expected '127-000.000.001|127.0.0.1'
    not ok 1 - selftest
not ok 1 - printf-kunit-test

Signed-off-by: Arpitha Raghunandan <98.arpi at gmail.com>
---
Changes v1->v2:
- Retain the control flow (early returns) in do_test()
- Display less irrelevant information on test failure
- A more detailed commit message

 lib/Kconfig.debug                     |  7 +--
 lib/Makefile                          |  2 +-
 lib/{test_printf.c => printf_kunit.c} | 76 +++++++++++++--------------
 3 files changed, 43 insertions(+), 42 deletions(-)
 rename lib/{test_printf.c => printf_kunit.c} (91%)

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 66d44d35cc97..e82ca893ed5b 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2053,9 +2053,6 @@ config TEST_STRSCPY
 config TEST_KSTRTOX
 	tristate "Test kstrto*() family of functions at runtime"
 
-config TEST_PRINTF
-	tristate "Test printf() family of functions at runtime"
-
 config TEST_BITMAP
 	tristate "Test bitmap_*() family of functions at runtime"
 	help
@@ -2282,6 +2279,10 @@ config BITS_TEST
 
 	  If unsure, say N.
 
+config PRINTF_KUNIT_TEST
+	tristate "KUnit test for printf() family of functions at runtime"
+	depends on KUNIT
+
 config TEST_UDELAY
 	tristate "udelay test driver"
 	help
diff --git a/lib/Makefile b/lib/Makefile
index ce45af50983a..c323447022b7 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -84,7 +84,6 @@ obj-$(CONFIG_TEST_SORT) += test_sort.o
 obj-$(CONFIG_TEST_USER_COPY) += test_user_copy.o
 obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_keys.o
 obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_key_base.o
-obj-$(CONFIG_TEST_PRINTF) += test_printf.o
 obj-$(CONFIG_TEST_BITMAP) += test_bitmap.o
 obj-$(CONFIG_TEST_STRSCPY) += test_strscpy.o
 obj-$(CONFIG_TEST_UUID) += test_uuid.o
@@ -352,3 +351,4 @@ obj-$(CONFIG_BITFIELD_KUNIT) += bitfield_kunit.o
 obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o
 obj-$(CONFIG_LINEAR_RANGES_TEST) += test_linear_ranges.o
 obj-$(CONFIG_BITS_TEST) += test_bits.o
+obj-$(CONFIG_PRINTF_KUNIT_TEST) += printf_kunit.o
diff --git a/lib/test_printf.c b/lib/printf_kunit.c
similarity index 91%
rename from lib/test_printf.c
rename to lib/printf_kunit.c
index 7ac87f18a10f..e4dc1b1c8972 100644
--- a/lib/test_printf.c
+++ b/lib/printf_kunit.c
@@ -5,6 +5,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <kunit/test.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -30,64 +31,57 @@
 #define PAD_SIZE 16
 #define FILL_CHAR '$'
 
-static unsigned total_tests __initdata;
-static unsigned failed_tests __initdata;
 static char *test_buffer __initdata;
 static char *alloced_buffer __initdata;
+struct kunit *kunittest;
 
-static int __printf(4, 0) __init
+static void __printf(4, 0) __init
 do_test(int bufsize, const char *expect, int elen,
 	const char *fmt, va_list ap)
 {
 	va_list aq;
 	int ret, written;
 
-	total_tests++;
-
 	memset(alloced_buffer, FILL_CHAR, BUF_SIZE + 2*PAD_SIZE);
 	va_copy(aq, ap);
 	ret = vsnprintf(test_buffer, bufsize, fmt, aq);
 	va_end(aq);
 
 	if (ret != elen) {
-		pr_warn("vsnprintf(buf, %d, \"%s\", ...) returned %d, expected %d\n",
+		KUNIT_FAIL(kunittest, "vsnprintf(buf, %d, \"%s\", ...) returned %d, expected %d\n",
 			bufsize, fmt, ret, elen);
-		return 1;
+		return;
 	}
 
 	if (memchr_inv(alloced_buffer, FILL_CHAR, PAD_SIZE)) {
-		pr_warn("vsnprintf(buf, %d, \"%s\", ...) wrote before buffer\n", bufsize, fmt);
-		return 1;
+		KUNIT_FAIL(kunittest, "vsnprintf(buf, %d, \"%s\", ...) wrote before buffer\n", bufsize, fmt);
+		return;
 	}
 
 	if (!bufsize) {
-		if (memchr_inv(test_buffer, FILL_CHAR, BUF_SIZE + PAD_SIZE)) {
-			pr_warn("vsnprintf(buf, 0, \"%s\", ...) wrote to buffer\n",
-				fmt);
-			return 1;
-		}
-		return 0;
+		if (memchr_inv(test_buffer, FILL_CHAR, BUF_SIZE + PAD_SIZE))
+			KUNIT_FAIL(kunittest, "vsnprintf(buf, 0, \"%s\", ...) wrote to buffer\n", fmt);
+		return;
 	}
 
 	written = min(bufsize-1, elen);
 	if (test_buffer[written]) {
-		pr_warn("vsnprintf(buf, %d, \"%s\", ...) did not nul-terminate buffer\n",
+		KUNIT_FAIL(kunittest, "vsnprintf(buf, %d, \"%s\", ...) did not nul-terminate buffer\n",
 			bufsize, fmt);
-		return 1;
+		return;
 	}
 
 	if (memchr_inv(test_buffer + written + 1, FILL_CHAR, BUF_SIZE + PAD_SIZE - (written + 1))) {
-		pr_warn("vsnprintf(buf, %d, \"%s\", ...) wrote beyond the nul-terminator\n",
+		KUNIT_FAIL(kunittest, "vsnprintf(buf, %d, \"%s\", ...) wrote beyond the nul-terminator\n",
 			bufsize, fmt);
-		return 1;
+		return;
 	}
 
 	if (memcmp(test_buffer, expect, written)) {
-		pr_warn("vsnprintf(buf, %d, \"%s\", ...) wrote '%s', expected '%.*s'\n",
+		KUNIT_FAIL(kunittest, "vsnprintf(buf, %d, \"%s\", ...) wrote '%s', expected '%.*s'\n",
 			bufsize, fmt, test_buffer, written, expect);
-		return 1;
+		return;
 	}
-	return 0;
 }
 
 static void __printf(3, 4) __init
@@ -98,9 +92,8 @@ __test(const char *expect, int elen, const char *fmt, ...)
 	char *p;
 
 	if (elen >= BUF_SIZE) {
-		pr_err("error in test suite: expected output length %d too long. Format was '%s'.\n",
+		KUNIT_FAIL(kunittest, "error in test suite: expected output length %d too long. Format was '%s'.\n",
 		       elen, fmt);
-		failed_tests++;
 		return;
 	}
 
@@ -112,19 +105,17 @@ __test(const char *expect, int elen, const char *fmt, ...)
 	 * enough and 0), and then we also test that kvasprintf would
 	 * be able to print it as expected.
 	 */
-	failed_tests += do_test(BUF_SIZE, expect, elen, fmt, ap);
+	do_test(BUF_SIZE, expect, elen, fmt, ap);
 	rand = 1 + prandom_u32_max(elen+1);
 	/* Since elen < BUF_SIZE, we have 1 <= rand <= BUF_SIZE. */
-	failed_tests += do_test(rand, expect, elen, fmt, ap);
-	failed_tests += do_test(0, expect, elen, fmt, ap);
+	do_test(rand, expect, elen, fmt, ap);
+	do_test(0, expect, elen, fmt, ap);
 
 	p = kvasprintf(GFP_KERNEL, fmt, ap);
 	if (p) {
-		total_tests++;
 		if (memcmp(p, expect, elen+1)) {
-			pr_warn("kvasprintf(..., \"%s\", ...) returned '%s', expected '%s'\n",
+			KUNIT_FAIL(kunittest, "kvasprintf(..., \"%s\", ...) returned '%s', expected '%s'\n",
 				fmt, p, expect);
-			failed_tests++;
 		}
 		kfree(p);
 	}
@@ -303,16 +294,13 @@ plain(void)
 
 	err = plain_hash();
 	if (err) {
-		pr_warn("plain 'p' does not appear to be hashed\n");
-		failed_tests++;
+		KUNIT_FAIL(kunittest, "plain 'p' does not appear to be hashed\n");
 		return;
 	}
 
 	err = plain_format();
-	if (err) {
-		pr_warn("hashing plain 'p' has unexpected format\n");
-		failed_tests++;
-	}
+	if (err)
+		KUNIT_FAIL(kunittest, "hashing plain 'p' has unexpected format\n");
 }
 
 static void __init
@@ -696,8 +684,9 @@ test_pointer(void)
 	fwnode_pointer();
 }
 
-static void __init selftest(void)
+static void __init selftest(struct kunit *ktest)
 {
+	kunittest = ktest;
 	alloced_buffer = kmalloc(BUF_SIZE + 2*PAD_SIZE, GFP_KERNEL);
 	if (!alloced_buffer)
 		return;
@@ -711,6 +700,17 @@ static void __init selftest(void)
 	kfree(alloced_buffer);
 }
 
-KSTM_MODULE_LOADERS(test_printf);
+static struct kunit_case printf_test_cases[] = {
+	KUNIT_CASE(selftest),
+	{}
+};
+
+static struct kunit_suite printf_test_suite = {
+	.name = "printf-kunit-test",
+	.test_cases = printf_test_cases,
+};
+
+kunit_test_suite(printf_test_suite);
+
 MODULE_AUTHOR("Rasmus Villemoes <linux at rasmusvillemoes.dk>");
 MODULE_LICENSE("GPL");
-- 
2.25.1



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