[PATCH] selftests: kselftest: Fix debug message formatting

[ZhuangZhuang Wang]

ksft_print_dbg_msg() passes a va_list to ksft_print_msg() as a regular
variadic argument. As a result, format specifiers consume the va_list
representation instead of the caller's arguments and print garbage.

Add a va_list-based helper and use it from both message printing
functions. Also annotate ksft_print_dbg_msg() so the compiler can check
its format arguments.

Fixes: f2662ec26b26 ("selftests: kselftest: Create ksft_print_dbg_msg()")
Signed-off-by: ZhuangZhuang Wang <wzz_123...@163.com>
---
 tools/testing/selftests/kselftest.h | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/kselftest.h 
b/tools/testing/selftests/kselftest.h
index ae18c491a..d815a8667 100644
--- a/tools/testing/selftests/kselftest.h
+++ b/tools/testing/selftests/kselftest.h
@@ -173,19 +173,25 @@ static inline void ksft_print_cnts(void)
                ksft_cnt.ksft_xskip, ksft_cnt.ksft_error);
 }
 
-static inline __printf(1, 2) void ksft_print_msg(const char *msg, ...)
+static inline void ksft_vprint_msg(const char *msg, va_list args)
 {
        int saved_errno = errno;
-       va_list args;
 
-       va_start(args, msg);
        printf("# ");
        errno = saved_errno;
        vprintf(msg, args);
+}
+
+static inline __printf(1, 2) void ksft_print_msg(const char *msg, ...)
+{
+       va_list args;
+
+       va_start(args, msg);
+       ksft_vprint_msg(msg, args);
        va_end(args);
 }
 
-static inline void ksft_print_dbg_msg(const char *msg, ...)
+static inline __printf(1, 2) void ksft_print_dbg_msg(const char *msg, ...)
 {
        va_list args;
 
@@ -193,7 +199,7 @@ static inline void ksft_print_dbg_msg(const char *msg, ...)
                return;
 
        va_start(args, msg);
-       ksft_print_msg(msg, args);
+       ksft_vprint_msg(msg, args);
        va_end(args);
 }