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

Suggested-by: Andy Shevchenko <[email protected]>
Signed-off-by: Feng Jiang <[email protected]>
---
 include/linux/string.h |  1 +
 lib/string.c           | 19 +++++++++++++------
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/include/linux/string.h b/include/linux/string.h
index 57f8bf543891..2ede3ff0865a 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -180,6 +180,7 @@ extern char * strnchrnul(const char *, size_t, int);
 #ifndef __HAVE_ARCH_STRNCHR
 extern char * strnchr(const char *, size_t, int);
 #endif
+extern char *__generic_strrchr(const char *, int);
 #ifndef __HAVE_ARCH_STRRCHR
 extern char * strrchr(const char *,int);
 #endif
diff --git a/lib/string.c b/lib/string.c
index 8ad9b73ffe4e..4405a042eee7 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -377,6 +377,18 @@ char *strnchrnul(const char *s, size_t count, int c)
        return (char *)s;
 }
 
+char *__generic_strrchr(const char *s, int c)
+{
+       const char *last = NULL;
+
+       do {
+               if (*s == (char)c)
+                       last = s;
+       } while (*s++);
+       return (char *)last;
+}
+EXPORT_SYMBOL(__generic_strrchr);
+
 #ifndef __HAVE_ARCH_STRRCHR
 /**
  * strrchr - Find the last occurrence of a character in a string
@@ -385,12 +397,7 @@ char *strnchrnul(const char *s, size_t count, int c)
  */
 char *strrchr(const char *s, int c)
 {
-       const char *last = NULL;
-       do {
-               if (*s == (char)c)
-                       last = s;
-       } while (*s++);
-       return (char *)last;
+       return __generic_strrchr(s, c);
 }
 EXPORT_SYMBOL(strrchr);
 #endif
-- 
2.25.1


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