Extend the string benchmarking suite to include strnlen(), strchr(),
and strrchr().

For character search functions strchr() and strrchr(), the benchmark
targets the NUL character. This ensures the entire string is scanned,
providing a consistent measure of full-length processing efficiency
comparable to strlen().

Suggested-by: Andy Shevchenko <andy@kernel.org>
Suggested-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Feng Jiang <jiangfeng@kylinos.cn>
Acked-by: Andy Shevchenko <andy@kernel.org>
---
 lib/tests/string_kunit.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/lib/tests/string_kunit.c b/lib/tests/string_kunit.c
index 5f6d0409459b..a8d430aa5466 100644
--- a/lib/tests/string_kunit.c
+++ b/lib/tests/string_kunit.c
@@ -866,6 +866,21 @@ static void string_bench_strlen(struct kunit *test)
 	STRING_BENCH_BUF(test, buf, len, strlen, buf);
 }
 
+static void string_bench_strnlen(struct kunit *test)
+{
+	STRING_BENCH_BUF(test, buf, len, strnlen, buf, len);
+}
+
+static void string_bench_strchr(struct kunit *test)
+{
+	STRING_BENCH_BUF(test, buf, len, strchr, buf, '\0');
+}
+
+static void string_bench_strrchr(struct kunit *test)
+{
+	STRING_BENCH_BUF(test, buf, len, strrchr, buf, '\0');
+}
+
 static struct kunit_case string_test_cases[] = {
 	KUNIT_CASE(string_test_memset16),
 	KUNIT_CASE(string_test_memset32),
@@ -892,6 +907,9 @@ static struct kunit_case string_test_cases[] = {
 	KUNIT_CASE(string_test_memtostr),
 	KUNIT_CASE(string_test_strends),
 	KUNIT_CASE(string_bench_strlen),
+	KUNIT_CASE(string_bench_strnlen),
+	KUNIT_CASE(string_bench_strchr),
+	KUNIT_CASE(string_bench_strrchr),
 	{}
 };
 
-- 
2.25.1

On Fri, Jan 30, 2026 at 10:50:15AM +0800, Feng Jiang wrote:
> Extend the string benchmarking suite to include strnlen(), strchr(),
> and strrchr().
> 
> For character search functions strchr() and strrchr(), the benchmark
> targets the NUL character. This ensures the entire string is scanned,
> providing a consistent measure of full-length processing efficiency
> comparable to strlen().
> 
> Suggested-by: Andy Shevchenko <andy@kernel.org>
> Suggested-by: Eric Biggers <ebiggers@kernel.org>
> Signed-off-by: Feng Jiang <jiangfeng@kylinos.cn>

Reviewed-by: Kees Cook <kees@kernel.org>

-- 
Kees Cook