once: implement DO_ONCE_LITE for non-fast-path "do once" functionality

Certain uses of "do once" functionality reside outside of fast path,
and so do not require jump label patching via static keys, making
existing DO_ONCE undesirable in such cases.

Replace uses of __section(".data.once") with DO_ONCE_LITE(_IF)?

This patch changes the return values of xfs_printk_once, printk_once,
and printk_deferred_once. Before, they returned whether the print was
performed, but now, they always return true. This is okay because the
return values of the following macros are entirely ignored throughout
the kernel:
- xfs_printk_once
- xfs_warn_once
- xfs_notice_once
- xfs_info_once
- printk_once
- pr_emerg_once
- pr_alert_once
- pr_crit_once
- pr_err_once
- pr_warn_once
- pr_notice_once
- pr_info_once
- pr_devel_once
- pr_debug_once
- printk_deferred_once
- orc_warn

Changes
v3:
  - Expand commit message to explain why changing return values of
    xfs_printk_once, printk_once, printk_deferred_once is benign
v2:
  - Fix i386 build warnings

Signed-off-by: Tanner Love <tannerlove@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Mahesh Bandewar <maheshb@google.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 30 deletions

diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
index b402494883b6..bafc51f483c4 100644
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -4,6 +4,7 @@
 
 #include <linux/compiler.h>
 #include <linux/instrumentation.h>
+#include <linux/once_lite.h>
 
 #define CUT_HERE		"------------[ cut here ]------------\n"
 
@@ -140,39 +141,15 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
 })
 
 #ifndef WARN_ON_ONCE
-#define WARN_ON_ONCE(condition)	({				\
-	static bool __section(".data.once") __warned;		\
-	int __ret_warn_once = !!(condition);			\
-								\
-	if (unlikely(__ret_warn_once && !__warned)) {		\
-		__warned = true;				\
-		WARN_ON(1);					\
-	}							\
-	unlikely(__ret_warn_once);				\
-})
+#define WARN_ON_ONCE(condition)					\
+	DO_ONCE_LITE_IF(condition, WARN_ON, 1)
 #endif
 
-#define WARN_ONCE(condition, format...)	({			\
-	static bool __section(".data.once") __warned;		\
-	int __ret_warn_once = !!(condition);			\
-								\
-	if (unlikely(__ret_warn_once && !__warned)) {		\
-		__warned = true;				\
-		WARN(1, format);				\
-	}							\
-	unlikely(__ret_warn_once);				\
-})
+#define WARN_ONCE(condition, format...)				\
+	DO_ONCE_LITE_IF(condition, WARN, 1, format)
 
-#define WARN_TAINT_ONCE(condition, taint, format...)	({	\
-	static bool __section(".data.once") __warned;		\
-	int __ret_warn_once = !!(condition);			\
-								\
-	if (unlikely(__ret_warn_once && !__warned)) {		\
-		__warned = true;				\
-		WARN_TAINT(1, taint, format);			\
-	}							\
-	unlikely(__ret_warn_once);				\
-})
+#define WARN_TAINT_ONCE(condition, taint, format...)		\
+	DO_ONCE_LITE_IF(condition, WARN_TAINT, 1, taint, format)
 
 #else /* !CONFIG_BUG */
 #ifndef HAVE_ARCH_BUG