From 090252f695f30755ccab5717e3b366b13eb2eb8b Mon Sep 17 00:00:00 2001
From: Bart Van Assche <bvanassche@acm.org>
Date: Sat, 6 Oct 2018 21:42:02 +0000
Subject: [PATCH] cst/include/backport.h: Add a printk_once() backport

This patch is only relevant for regression testing SCST against kernel
2.6.29 or older.


git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@7495 d57e44dd-8a1f-0410-8b47-8ef2f437770f
---
 scst/include/backport.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/scst/include/backport.h b/scst/include/backport.h
index 3455f3769..b3af751fb 100644
--- a/scst/include/backport.h
+++ b/scst/include/backport.h
@@ -569,6 +569,21 @@ static inline long get_user_pages_backport(unsigned long start,
 #endif
 #endif /* LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 30) */
 
+/* See also commit f036be96dd9c ("printk: introduce printk_once()") */
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 30)
+#define printk_once(fmt, ...)					\
+({								\
+	static bool __print_once __read_mostly;			\
+	bool __ret_print_once = !__print_once;			\
+								\
+	if (!__print_once) {					\
+		__print_once = true;				\
+		printk(fmt, ##__VA_ARGS__);			\
+	}							\
+	unlikely(__ret_print_once);				\
+})
+#endif
+
 #if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 35)
 /*
  * See also patch "kernel.h: add pr_warn for symmetry to dev_warn,