[PATCH v3 1/2] printf: convert self-test to KUnit

10 Feb 2025

Convert the printf() self-test to a KUnit test.
In the interest of keeping the patch reasonably-sized this doesn't
refactor the tests into proper parameterized tests - it's all one big
test case.
Signed-off-by: Tamir Duberstein tamird@gmail.com
---
 Documentation/core-api/printk-formats.rst |   2 +-
 MAINTAINERS                               |   2 +-
 lib/Kconfig.debug                         |  12 +-
 lib/Makefile                              |   2 +-
 lib/{test_printf.c => printf_kunit.c}     | 188 +++++++++++++++++-------------
 tools/testing/selftests/lib/config        |   1 -
 tools/testing/selftests/lib/printf.sh     |   4 -
 7 files changed, 116 insertions(+), 95 deletions(-)

diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
index ecccc0473da9..0d9461bd6964 100644
--- a/Documentation/core-api/printk-formats.rst
+++ b/Documentation/core-api/printk-formats.rst
@@ -661,7 +661,7 @@ Do *not* use it from C.
 Thanks
 ======
-If you add other %p extensions, please extend <lib/test_printf.c> with
+If you add other %p extensions, please extend <lib/printf_kunit.c> with
 one or more test cases, if at all feasible.
Thank you for your cooperation and attention.
diff --git a/MAINTAINERS b/MAINTAINERS
index 25c86f47353d..2d58914c7dd9 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -25411,7 +25411,7 @@ R:	Sergey Senozhatsky senozhatsky@chromium.org
 S:	Maintained
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux.git
 F:	Documentation/core-api/printk-formats.rst
-F:	lib/test_printf.c
+F:	lib/printf_kunit.c
 F:	lib/test_scanf.c
 F:	lib/vsprintf.c
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 1af972a92d06..9f1e0d3513fb 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2427,6 +2427,15 @@ config ASYNC_RAID6_TEST
 config TEST_HEXDUMP
    tristate "Test functions located in the hexdump module at runtime"
+config PRINTF_KUNIT_TEST
+	tristate "KUnit test printf() family of functions at runtime" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  Enable this option to test the printf functions at runtime.
+
+	  If unsure, say N.
+
 config STRING_KUNIT_TEST
    tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS
    depends on KUNIT
@@ -2440,9 +2449,6 @@ config STRING_HELPERS_KUNIT_TEST
 config TEST_KSTRTOX
    tristate "Test kstrto*() family of functions at runtime"
-config TEST_PRINTF
-	tristate "Test printf() family of functions at runtime"
-
 config TEST_SCANF
    tristate "Test scanf() family of functions at runtime"
diff --git a/lib/Makefile b/lib/Makefile
index d5cfc7afbbb8..844665b1f0e7 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -84,7 +84,7 @@ obj-$(CONFIG_TEST_SORT) += test_sort.o
 obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_keys.o
 obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_key_base.o
 obj-$(CONFIG_TEST_DYNAMIC_DEBUG) += test_dynamic_debug.o
-obj-$(CONFIG_TEST_PRINTF) += test_printf.o
+obj-$(CONFIG_PRINTF_KUNIT_TEST) += printf_kunit.o
 obj-$(CONFIG_TEST_SCANF) += test_scanf.o
obj-$(CONFIG_TEST_BITMAP) += test_bitmap.o
diff --git a/lib/test_printf.c b/lib/printf_kunit.c
similarity index 87%
rename from lib/test_printf.c
rename to lib/printf_kunit.c
index 59dbe4f9a4cb..287bbfb61148 100644
--- a/lib/test_printf.c
+++ b/lib/printf_kunit.c
@@ -3,9 +3,7 @@
  * Test cases for printf facility.
  */
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-
-#include <linux/init.h>
+#include <kunit/test.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/printk.h>
@@ -25,8 +23,6 @@
#include <linux/property.h>
-#include "../tools/testing/selftests/kselftest_module.h"
-
 #define BUF_SIZE 256
 #define PAD_SIZE 16
 #define FILL_CHAR '$'
@@ -37,12 +33,17 @@
    block \
    __diag_pop();
-KSTM_MODULE_GLOBALS();
+static unsigned int total_tests;
+
+static char *test_buffer;
+static char *alloced_buffer;
+
+static struct kunit *kunittest;
-static char *test_buffer __initdata;
-static char *alloced_buffer __initdata;
+#define tc_fail(fmt, ...) \
+	KUNIT_FAIL(kunittest, fmt, ##__VA_ARGS__)
-static int __printf(4, 0) __init
+static void __printf(4, 0)
 do_test(int bufsize, const char *expect, int elen,
    const char *fmt, va_list ap)
 {
@@ -57,52 +58,50 @@ do_test(int bufsize, const char *expect, int elen,
    va_end(aq);
if (ret != elen) {
-		pr_warn("vsnprintf(buf, %d, "%s", ...) returned %d, expected %d\n",
+		tc_fail("vsnprintf(buf, %d, "%s", ...) returned %d, expected %d",
    		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;
+		tc_fail("vsnprintf(buf, %d, "%s", ...) wrote before buffer",
+			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;
+			tc_fail("vsnprintf(buf, 0, "%s", ...) wrote to buffer", fmt);
    	}
-		return 0;
+		return;
    }
written = min(bufsize-1, elen);
    if (test_buffer[written]) {
-		pr_warn("vsnprintf(buf, %d, "%s", ...) did not nul-terminate buffer\n",
+		tc_fail("vsnprintf(buf, %d, "%s", ...) did not nul-terminate buffer",
    		bufsize, fmt);
-		return 1;
+		return;
    }
if (memchr_inv(test_buffer + written + 1, FILL_CHAR, bufsize - (written + 1))) {
-		pr_warn("vsnprintf(buf, %d, "%s", ...) wrote beyond the nul-terminator\n",
+		tc_fail("vsnprintf(buf, %d, "%s", ...) wrote beyond the nul-terminator",
    		bufsize, fmt);
-		return 1;
+		return;
    }
if (memchr_inv(test_buffer + bufsize, FILL_CHAR, BUF_SIZE + PAD_SIZE - bufsize)) {
-		pr_warn("vsnprintf(buf, %d, "%s", ...) wrote beyond buffer\n", bufsize, fmt);
-		return 1;
+		tc_fail("vsnprintf(buf, %d, "%s", ...) wrote beyond buffer", bufsize, fmt);
+		return;
    }
if (memcmp(test_buffer, expect, written)) {
-		pr_warn("vsnprintf(buf, %d, "%s", ...) wrote '%s', expected '%.*s'\n",
+		tc_fail("vsnprintf(buf, %d, "%s", ...) wrote '%s', expected '%.*s'",
    		bufsize, fmt, test_buffer, written, expect);
-		return 1;
+		return;
    }
-	return 0;
 }
-static void __printf(3, 4) __init
+static void __printf(3, 4)
 __test(const char *expect, int elen, const char *fmt, ...)
 {
    va_list ap;
@@ -110,9 +109,8 @@ __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",
-		       elen, fmt);
-		failed_tests++;
+		tc_fail("error in test suite: expected output length %d too long. Format was '%s'.",
+			elen, fmt);
    	return;
    }
@@ -124,19 +122,18 @@ __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 = get_random_u32_inclusive(1, 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",
+			tc_fail("kvasprintf(..., "%s", ...) returned '%s', expected '%s'",
    			fmt, p, expect);
-			failed_tests++;
    	}
    	kfree(p);
    }
@@ -146,7 +143,7 @@ __test(const char *expect, int elen, const char *fmt, ...)
 #define test(expect, fmt, ...)					\
    __test(expect, strlen(expect), fmt, ##__VA_ARGS__)
-static void __init
+static void
 test_basic(void)
 {
    /* Work around annoying "warning: zero-length gnu_printf format string". */
@@ -158,7 +155,7 @@ test_basic(void)
    __test("xxx\0yyy", 7, "xxx%cyyy", '\0');
 }
-static void __init
+static void
 test_number(void)
 {
    test("0x1234abcd  ", "%#-12x", 0x1234abcd);
@@ -180,7 +177,7 @@ test_number(void)
    test("00|0|0|0|0", "%.2d|%.1d|%.0d|%.*d|%1.0d", 0, 0, 0, 0, 0, 0);
 }
-static void __init
+static void
 test_string(void)
 {
    test("", "%s%.0s", "", "123");
@@ -218,7 +215,7 @@ test_string(void)
 #define ZEROS "00000000"	/* hex 32 zero bits */
 #define ONES "ffffffff"		/* hex 32 one bits */
-static int __init
+static int
 plain_format(void)
 {
    char buf[PLAIN_BUF_SIZE];
@@ -230,7 +227,7 @@ plain_format(void)
    	return -1;
if (strncmp(buf, PTR_VAL_NO_CRNG, PTR_WIDTH) == 0) {
-		pr_warn("crng possibly not yet initialized. plain 'p' buffer contains "%s"",
+		kunit_warn(kunittest, "crng possibly not yet initialized. plain 'p' buffer contains "%s"",
    		PTR_VAL_NO_CRNG);
    	return 0;
    }
@@ -250,7 +247,7 @@ plain_format(void)
 #define ZEROS ""
 #define ONES ""
-static int __init
+static int
 plain_format(void)
 {
    /* Format is implicitly tested for 32 bit machines by plain_hash() */
@@ -259,7 +256,7 @@ plain_format(void)
#endif	/* BITS_PER_LONG == 64 */
-static int __init
+static int
 plain_hash_to_buffer(const void *p, char *buf, size_t len)
 {
    int nchars;
@@ -270,7 +267,7 @@ plain_hash_to_buffer(const void *p, char *buf, size_t len)
    	return -1;
if (strncmp(buf, PTR_VAL_NO_CRNG, PTR_WIDTH) == 0) {
-		pr_warn("crng possibly not yet initialized. plain 'p' buffer contains "%s"",
+		kunit_warn(kunittest, "crng possibly not yet initialized. plain 'p' buffer contains "%s"",
    		PTR_VAL_NO_CRNG);
    	return 0;
    }
@@ -278,7 +275,7 @@ plain_hash_to_buffer(const void *p, char *buf, size_t len)
    return 0;
 }
-static int __init
+static int
 plain_hash(void)
 {
    char buf[PLAIN_BUF_SIZE];
@@ -298,32 +295,29 @@ plain_hash(void)
  * We can't use test() to test %p because we don't know what output to expect
  * after an address is hashed.
  */
-static void __init
+static void
 plain(void)
 {
    int err;
if (no_hash_pointers) {
-		pr_warn("skipping plain 'p' tests");
-		skipped_tests += 2;
+		kunit_warn(kunittest, "skipping plain 'p' tests");
    	return;
    }
err = plain_hash();
    if (err) {
-		pr_warn("plain 'p' does not appear to be hashed\n");
-		failed_tests++;
+		tc_fail("plain 'p' does not appear to be hashed");
    	return;
    }
err = plain_format();
    if (err) {
-		pr_warn("hashing plain 'p' has unexpected format\n");
-		failed_tests++;
+		tc_fail("hashing plain 'p' has unexpected format");
    }
 }
-static void __init
+static void
 test_hashed(const char *fmt, const void *p)
 {
    char buf[PLAIN_BUF_SIZE];
@@ -343,7 +337,7 @@ test_hashed(const char *fmt, const void *p)
 /*
  * NULL pointers aren't hashed.
  */
-static void __init
+static void
 null_pointer(void)
 {
    test(ZEROS "00000000", "%p", NULL);
@@ -354,7 +348,7 @@ null_pointer(void)
 /*
  * Error pointers aren't hashed.
  */
-static void __init
+static void
 error_pointer(void)
 {
    test(ONES "fffffff5", "%p", ERR_PTR(-11));
@@ -364,7 +358,7 @@ error_pointer(void)
#define PTR_INVALID ((void *)0x000000ab)
-static void __init
+static void
 invalid_pointer(void)
 {
    test_hashed("%p", PTR_INVALID);
@@ -372,18 +366,18 @@ invalid_pointer(void)
    test("(efault)", "%pE", PTR_INVALID);
 }
-static void __init
+static void
 symbol_ptr(void)
 {
 }
-static void __init
+static void
 kernel_ptr(void)
 {
    /* We can't test this without access to kptr_restrict. */
 }
-static void __init
+static void
 struct_resource(void)
 {
    struct resource test_resource = {
@@ -432,7 +426,7 @@ struct_resource(void)
         "%pR", &test_resource);
 }
-static void __init
+static void
 struct_range(void)
 {
    struct range test_range = DEFINE_RANGE(0xc0ffee00ba5eba11,
@@ -448,17 +442,17 @@ struct_range(void)
         "%pra", &test_range);
 }
-static void __init
+static void
 addr(void)
 {
 }
-static void __init
+static void
 escaped_str(void)
 {
 }
-static void __init
+static void
 hex_string(void)
 {
    const char buf[3] = {0xc0, 0xff, 0xee};
@@ -469,7 +463,7 @@ hex_string(void)
         "%*ph|%*phC|%*phD|%*phN", 3, buf, 3, buf, 3, buf, 3, buf);
 }
-static void __init
+static void
 mac(void)
 {
    const u8 addr[6] = {0x2d, 0x48, 0xd6, 0xfc, 0x7a, 0x05};
@@ -481,7 +475,7 @@ mac(void)
    test("057afcd6482d", "%pmR", addr);
 }
-static void __init
+static void
 ip4(void)
 {
    struct sockaddr_in sa;
@@ -496,19 +490,19 @@ ip4(void)
    test("001.002.003.004:12345|1.2.3.4:12345", "%piSp|%pISp", &sa, &sa);
 }
-static void __init
+static void
 ip6(void)
 {
 }
-static void __init
+static void
 ip(void)
 {
    ip4();
    ip6();
 }
-static void __init
+static void
 uuid(void)
 {
    const char uuid[16] = {0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7,
@@ -520,7 +514,7 @@ uuid(void)
    test("03020100-0504-0706-0809-0A0B0C0D0E0F", "%pUL", uuid);
 }
-static struct dentry test_dentry[4] __initdata = {
+static struct dentry test_dentry[4] = {
    { .d_parent = &test_dentry[0],
      .d_name = QSTR_INIT(test_dentry[0].d_iname, 3),
      .d_iname = "foo" },
@@ -535,7 +529,7 @@ static struct dentry test_dentry[4] __initdata = {
      .d_iname = "romeo" },
 };
-static void __init
+static void
 dentry(void)
 {
    test("foo", "%pd", &test_dentry[0]);
@@ -556,12 +550,12 @@ dentry(void)
    test("  bravo/alfa|  bravo/alfa", "%12pd2|%*pd2", &test_dentry[2], 12, &test_dentry[2]);
 }
-static void __init
+static void
 struct_va_format(void)
 {
 }
-static void __init
+static void
 time_and_date(void)
 {
    /* 1543210543 */
@@ -595,12 +589,12 @@ time_and_date(void)
    test("15:32:23|0119-00-04", "%ptTtrs|%ptTdrs", &t, &t);
 }
-static void __init
+static void
 struct_clk(void)
 {
 }
-static void __init
+static void
 large_bitmap(void)
 {
    const int nbits = 1 << 16;
@@ -614,7 +608,7 @@ large_bitmap(void)
    bitmap_free(bits);
 }
-static void __init
+static void
 bitmap(void)
 {
    DECLARE_BITMAP(bits, 20);
@@ -637,7 +631,7 @@ bitmap(void)
    large_bitmap();
 }
-static void __init
+static void
 netdev_features(void)
 {
 }
@@ -663,7 +657,7 @@ static const struct page_flags_test pft[] = {
     "%#x", "kasantag"},
 };
-static void __init
+static void
 page_flags_test(int section, int node, int zone, int last_cpupid,
    	int kasan_tag, unsigned long flags, const char *name,
    	char *cmp_buf)
@@ -701,7 +695,7 @@ page_flags_test(int section, int node, int zone, int last_cpupid,
    test(cmp_buf, "%pGp", &flags);
 }
-static void __init
+static void
 flags(void)
 {
    unsigned long flags;
@@ -749,7 +743,7 @@ flags(void)
    kfree(cmp_buffer);
 }
-static void __init fwnode_pointer(void)
+static void fwnode_pointer(void)
 {
    const struct software_node first = { .name = "first" };
    const struct software_node second = { .name = "second", .parent = &first };
@@ -763,7 +757,7 @@ static void __init fwnode_pointer(void)
rval = software_node_register_node_group(group);
    if (rval) {
-		pr_warn("cannot register softnodes; rval %d\n", rval);
+		kunit_warn(kunittest, "cannot register softnodes; rval %d", rval);
    	return;
    }
@@ -776,7 +770,7 @@ static void __init fwnode_pointer(void)
    software_node_unregister_node_group(group);
 }
-static void __init fourcc_pointer(void)
+static void fourcc_pointer(void)
 {
    struct {
    	u32 code;
@@ -793,7 +787,7 @@ static void __init fourcc_pointer(void)
    	test(try[i].str, "%p4cc", &try[i].code);
 }
-static void __init
+static void
 errptr(void)
 {
    test("-1234", "%pe", ERR_PTR(-1234));
@@ -813,7 +807,7 @@ errptr(void)
 #endif
 }
-static void __init
+static void
 test_pointer(void)
 {
    plain();
@@ -842,13 +836,15 @@ test_pointer(void)
    fourcc_pointer();
 }
-static void __init selftest(void)
+static void printf_test(struct kunit *test)
 {
    alloced_buffer = kmalloc(BUF_SIZE + 2*PAD_SIZE, GFP_KERNEL);
    if (!alloced_buffer)
    	return;
    test_buffer = alloced_buffer + PAD_SIZE;
+	kunittest = test;
+
    test_basic();
    test_number();
    test_string();
@@ -857,7 +853,31 @@ static void __init selftest(void)
    kfree(alloced_buffer);
 }
-KSTM_MODULE_LOADERS(test_printf);
+static int printf_suite_init(struct kunit_suite *suite)
+{
+	total_tests = 0;
+	return 0;
+}
+
+static void printf_suite_exit(struct kunit_suite *suite)
+{
+	kunit_info(suite, "ran %u tests", total_tests);
+}
+
+static struct kunit_case printf_test_cases[] = {
+	KUNIT_CASE(printf_test),
+	{}
+};
+
+static struct kunit_suite printf_test_suite = {
+	.name = "printf",
+	.suite_init = printf_suite_init,
+	.suite_exit = printf_suite_exit,
+	.test_cases = printf_test_cases,
+};
+
+kunit_test_suite(printf_test_suite);
+
 MODULE_AUTHOR("Rasmus Villemoes linux@rasmusvillemoes.dk");
 MODULE_DESCRIPTION("Test cases for printf facility");
 MODULE_LICENSE("GPL");
diff --git a/tools/testing/selftests/lib/config b/tools/testing/selftests/lib/config
index dc15aba8d0a3..0a63594177c2 100644
--- a/tools/testing/selftests/lib/config
+++ b/tools/testing/selftests/lib/config
@@ -1,4 +1,3 @@
-CONFIG_TEST_PRINTF=m
 CONFIG_TEST_SCANF=m
 CONFIG_TEST_BITMAP=m
 CONFIG_PRIME_NUMBERS=m
diff --git a/tools/testing/selftests/lib/printf.sh b/tools/testing/selftests/lib/printf.sh
deleted file mode 100755
index 05f4544e87f9..000000000000
--- a/tools/testing/selftests/lib/printf.sh
+++ /dev/null
@@ -1,4 +0,0 @@
-#!/bin/sh
-# SPDX-License-Identifier: GPL-2.0
-# Tests the printf infrastructure using test_printf kernel module.
-$(dirname $0)/../kselftest/module.sh "printf" test_printf
-- 
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[PATCH v3 1/2] printf: convert self-test to KUnit