bug: Implement WARN_ON() using __WARN_FLAGS()

This completes 3bc3c9c ("bugs/core: Pass down the condition
string of WARN_ON_ONCE(cond) warnings to __WARN_FLAGS()") and makes
WARN_ON() and WARN_ON_ONCE() behaviour consistent.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251110115757.690999560@infradead.org

Author: Peter Zijlstra

include/asm-generic/bug.h

@@ -109,21 +109,35 @@ extern __printf(1, 2) void __warn_printk(const char *fmt, ...);
 	} while (0)
 #else
 #define __WARN()		__WARN_FLAGS("", BUGFLAG_TAINT(TAINT_WARN))
+
 #define __WARN_printf(taint, arg...) do {				\
 		instrumentation_begin();				\
 		__warn_printk(arg);					\
 		__WARN_FLAGS("", BUGFLAG_NO_CUT_HERE | BUGFLAG_TAINT(taint));\
 		instrumentation_end();					\
 	} while (0)
-#define WARN_ON_ONCE(condition) ({				\
-	int __ret_warn_on = !!(condition);			\
-	if (unlikely(__ret_warn_on))				\
-		__WARN_FLAGS("["#condition"] ",			\
-			     BUGFLAG_ONCE |			\
-			     BUGFLAG_TAINT(TAINT_WARN));	\
-	unlikely(__ret_warn_on);				\
+
+#ifndef WARN_ON
+#define WARN_ON(condition) ({						\
+	int __ret_warn_on = !!(condition);				\
+	if (unlikely(__ret_warn_on))					\
+		__WARN_FLAGS("["#condition"] ",				\
+			     BUGFLAG_TAINT(TAINT_WARN));		\
+	unlikely(__ret_warn_on);					\
+})
+#endif
+
+#ifndef WARN_ON_ONCE
+#define WARN_ON_ONCE(condition) ({					\
+	int __ret_warn_on = !!(condition);				\
+	if (unlikely(__ret_warn_on))					\
+		__WARN_FLAGS("["#condition"] ",				\
+			     BUGFLAG_ONCE |				\
+			     BUGFLAG_TAINT(TAINT_WARN));		\
+	unlikely(__ret_warn_on);					\
 })
 #endif
+#endif /* __WARN_FLAGS */
 
 /* used internally by panic.c */