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authorIngo Molnar <mingo@elte.hu>2009-02-05 13:45:43 +0100
committerIngo Molnar <mingo@elte.hu>2009-02-05 13:52:29 +0100
commitf036be96dd9ce442ffb9ab33e3c165f5178815c0 (patch)
treec60c39f895bb93ac0000de7772e89a0b6663954b /include/linux/kernel.h
parenteda58a85ec3fc05855a26654d97a2b53f0e715b9 (diff)
downloadtalos-op-linux-f036be96dd9ce442ffb9ab33e3c165f5178815c0.tar.gz
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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>
Diffstat (limited to 'include/linux/kernel.h')
-rw-r--r--include/linux/kernel.h17
1 files changed, 17 insertions, 0 deletions
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 343df9ef2412..3c183d9864ae 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);
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