Implement WARN_ONCE like WARN using BUGFLAG_ONCE.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 arch/x86/include/asm/bug.h |   14 ++++++++++++++
 include/asm-generic/bug.h  |    2 ++
 2 files changed, 16 insertions(+)

--- a/arch/x86/include/asm/bug.h
+++ b/arch/x86/include/asm/bug.h
@@ -152,6 +152,20 @@ do {									\
 #define __WARN_printf(taint, fmt, arg...) \
 	__WARN_print_arg(BUGFLAG_TAINT(taint), fmt, ## arg)
 
+#define __WARN_ONCE(cond, format, arg...) ({				\
+	int __ret_warn_on = !!(cond);					\
+	if (unlikely(__ret_warn_on)) {					\
+		__WARN_print_arg(BUGFLAG_ONCE|BUGFLAG_TAINT(TAINT_WARN),\
+				format, ## arg);			\
+	}								\
+	__ret_warn_on;							\
+})
+
+/*
+ * Make sure WARN_ONCE() arguments get expanded before trying to count them.
+ */
+#define WARN_ONCE(cond, format...) __WARN_ONCE(cond, format)
+
 #endif /* HAVE_ARCH_BUG_FORMAT */
 
 #include <asm-generic/bug.h>
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -155,8 +155,10 @@ extern __printf(1, 2) void __warn_printk
 	DO_ONCE_LITE_IF(condition, WARN_ON, 1)
 #endif
 
+#ifndef WARN_ONCE
 #define WARN_ONCE(condition, format...)				\
 	DO_ONCE_LITE_IF(condition, WARN, 1, format)
+#endif
 
 #define WARN_TAINT_ONCE(condition, taint, format...)		\
 	DO_ONCE_LITE_IF(condition, WARN_TAINT, 1, taint, format)