From f036be96dd9ce442ffb9ab33e3c165f5178815c0 Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Thu, 5 Feb 2009 13:45:43 +0100
Subject: [PATCH] printk: introduce printk_once()
This pattern shows up frequently in the kernel:
static int once = 1;
...
if (once) {
once = 0;
printk(KERN_ERR "message\n");
}
...
So add a printk_once() helper macro that reduces this to a single line
of:
printk_once(KERN_ERR "message\n");
It works analogously to WARN_ONCE() & friends. (We use a macro not
an inline because vararg expansion in inlines looks awkward and the
macro is simple enough.)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
include/linux/kernel.h | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 343df9ef241..3c183d9864a 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -242,6 +242,19 @@ extern struct ratelimit_state printk_ratelimit_state;
extern int printk_ratelimit(void);
extern bool printk_timed_ratelimit(unsigned long *caller_jiffies,
unsigned int interval_msec);
+
+/*
+ * Print a one-time message (analogous to WARN_ONCE() et al):
+ */
+#define printk_once(x...) ({ \
+ static int __print_once = 1; \
+ \
+ if (__print_once) { \
+ __print_once = 0; \
+ printk(x); \
+ } \
+})
+
#else
static inline int vprintk(const char *s, va_list args)
__attribute__ ((format (printf, 1, 0)));
@@ -253,6 +266,10 @@ static inline int printk_ratelimit(void) { return 0; }
static inline bool printk_timed_ratelimit(unsigned long *caller_jiffies, \
unsigned int interval_msec) \
{ return false; }
+
+/* No effect, but we still get type checking even in the !PRINTK case: */
+#define printk_once(x...) printk(x)
+
#endif
extern int printk_needs_cpu(int cpu);
--
2.41.3