Re: [PATCH] module: Prevent recursion bug caused by module RCU check

[Peter Zijlstra <peterz@infradead.org>]

On Tue, Oct 20, 2015 at 06:53:31PM +0200, Peter Zijlstra wrote:
> Also, would it not be better to fix WARN_ON_ONCE() instead?
> 

Clearly I'm an idiot and should stay away from the computer...

---
 include/asm-generic/bug.h | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
index 630dd2372238..d0972fc8433f 100644
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -110,9 +110,10 @@ extern void warn_slowpath_null(const char *file, const int line);
 	static bool __section(.data.unlikely) __warned;		\
 	int __ret_warn_once = !!(condition);			\
 								\
-	if (unlikely(__ret_warn_once))				\
-		if (WARN_ON(!__warned)) 			\
-			__warned = true;			\
+	if (unlikely(__ret_warn_once && !__warned)) {		\
+		__warned = true;				\
+		WARN_ON(1);					\
+	}							\
 	unlikely(__ret_warn_once);				\
 })
 
@@ -120,9 +121,10 @@ extern void warn_slowpath_null(const char *file, const int line);
 	static bool __section(.data.unlikely) __warned;		\
 	int __ret_warn_once = !!(condition);			\
 								\
-	if (unlikely(__ret_warn_once))				\
-		if (WARN(!__warned, format)) 			\
-			__warned = true;			\
+	if (unlikely(__ret_warn_once && !__warned)) {		\
+		__warned = true;				\
+		WARN(1, format);				\
+	}							\
 	unlikely(__ret_warn_once);				\
 })