printk: Add printk_deferred_once

Two of the three prink_deferred uses are really printk_once style
uses, so add a printk_deferred_once macro to simplify those call
sites.

Signed-off-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/printk.h b/include/linux/printk.h
index 7847301..f086d6c 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -266,9 +266,20 @@
 		printk(fmt, ##__VA_ARGS__);			\
 	}							\
 })
+#define printk_deferred_once(fmt, ...)				\
+({								\
+	static bool __print_once __read_mostly;			\
+								\
+	if (!__print_once) {					\
+		__print_once = true;				\
+		printk_deferred(fmt, ##__VA_ARGS__);		\
+	}							\
+})
 #else
 #define printk_once(fmt, ...)					\
 	no_printk(fmt, ##__VA_ARGS__)
+#define printk_deferred_once(fmt, ...)				\
+	no_printk(fmt, ##__VA_ARGS__)
 #endif
 
 #define pr_emerg_once(fmt, ...)					\