modpost: inform compilers that fatal() never returns

The function fatal() never returns because modpost_log() calls exit(1)
when LOG_FATAL is passed.

Inform compilers of this fact so that unreachable code flow can be
identified at compile time.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>

scripts/mod/modpost.c

@@ -90,6 +90,9 @@ void modpost_log(enum loglevel loglevel, const char *fmt, ...)
 		error_occurred = true;
 }
 
+void __attribute__((alias("modpost_log")))
+modpost_log_noret(enum loglevel loglevel, const char *fmt, ...);
+
 static inline bool strends(const char *str, const char *postfix)
 {
 	if (strlen(str) < strlen(postfix))

scripts/mod/modpost.h

@@ -200,6 +200,9 @@ enum loglevel {
 void __attribute__((format(printf, 2, 3)))
 modpost_log(enum loglevel loglevel, const char *fmt, ...);
 
+void __attribute__((format(printf, 2, 3), noreturn))
+modpost_log_noret(enum loglevel loglevel, const char *fmt, ...);
+
 /*
  * warn - show the given message, then let modpost continue running, still
  *        allowing modpost to exit successfully. This should be used when
@@ -215,4 +218,4 @@ modpost_log(enum loglevel loglevel, const char *fmt, ...);
  */
 #define warn(fmt, args...)	modpost_log(LOG_WARN, fmt, ##args)
 #define error(fmt, args...)	modpost_log(LOG_ERROR, fmt, ##args)
-#define fatal(fmt, args...)	modpost_log(LOG_FATAL, fmt, ##args)
+#define fatal(fmt, args...)	modpost_log_noret(LOG_FATAL, fmt, ##args)