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Commit f036be96 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

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: default avatarIngo Molnar <mingo@elte.hu>
parent eda58a85

include/linux/kernel.h

+17 −0
Original line number Diff line number Diff line
@@ -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);