linux-kernel - [PATCH v2 02/14] lib/string: extract generic strnlen() into __generic

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Message-Id: <20260113082748.250916-3-jiangfeng@kylinos.cn>
Date: Tue, 13 Jan 2026 16:27:36 +0800
From: Feng Jiang <jiangfeng@...inos.cn>
To: pjw@...nel.org,
	palmer@...belt.com,
	aou@...s.berkeley.edu,
	alex@...ti.fr,
	kees@...nel.org,
	andy@...nel.org,
	akpm@...ux-foundation.org,
	jiangfeng@...inos.cn,
	ebiggers@...nel.org,
	martin.petersen@...cle.com,
	ardb@...nel.org,
	ajones@...tanamicro.com,
	conor.dooley@...rochip.com,
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	nathan@...nel.org
Cc: linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org
Subject: [PATCH v2 02/14] lib/string: extract generic strnlen() into __generic_strnlen()

To support performance benchmarking in KUnit tests, extract the
generic C implementation of strnlen() into a standalone function
__generic_strnlen(). This allows tests to compare architecture-optimized
versions against the generic baseline without duplicating code.

Suggested-by: Andy Shevchenko <andy@...nel.org>
Signed-off-by: Feng Jiang <jiangfeng@...inos.cn>
---
 include/linux/string.h |  1 +
 lib/string.c           | 10 ++++++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/linux/string.h b/include/linux/string.h
index 961645633b4d..04b5fef7a4ec 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -201,6 +201,7 @@ extern __kernel_size_t __generic_strlen(const char *);
 #ifndef __HAVE_ARCH_STRLEN
 extern __kernel_size_t strlen(const char *);
 #endif
+extern __kernel_size_t __generic_strnlen(const char *, __kernel_size_t);
 #ifndef __HAVE_ARCH_STRNLEN
 extern __kernel_size_t strnlen(const char *,__kernel_size_t);
 #endif
diff --git a/lib/string.c b/lib/string.c
index 047ecb38e09b..9dfe7177e290 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -430,8 +430,7 @@ size_t strlen(const char *s)
 EXPORT_SYMBOL(strlen);
 #endif
 
-#ifndef __HAVE_ARCH_STRNLEN
-size_t strnlen(const char *s, size_t count)
+size_t __generic_strnlen(const char *s, size_t count)
 {
 	const char *sc;
 
@@ -439,6 +438,13 @@ size_t strnlen(const char *s, size_t count)
 		/* nothing */;
 	return sc - s;
 }
+EXPORT_SYMBOL(__generic_strnlen);
+
+#ifndef __HAVE_ARCH_STRNLEN
+size_t strnlen(const char *s, size_t count)
+{
+	return __generic_strnlen(s, count);
+}
 EXPORT_SYMBOL(strnlen);
 #endif
 
-- 
2.25.1