linux-kernel - [PATCH] do not export kernel's NULL #define to userspace

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Date:	Wed, 21 Mar 2012 14:08:24 +0100
From:	Lubos Lunak <l.lunak@...e.cz>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] do not export kernel's NULL #define to userspace

GCC's NULL is actually __null, which allows detecting some questionable
NULL usage and warn about it. Moreover each platform/compiler should have
its own stddef.h anyway (which is different from linux/stddef.h).
So there's no good reason to leak kernel's NULL to userspace and
override what the compiler provides.

Signed-off-by: Luboš Luňák <l.lunak@...e.cz>
---
 include/linux/stddef.h |    8 ++------
 1 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/include/linux/stddef.h b/include/linux/stddef.h
index 6a40c76..1747b67 100644
--- a/include/linux/stddef.h
+++ b/include/linux/stddef.h
@@ -3,14 +3,10 @@
 
 #include <linux/compiler.h>
 
+#ifdef __KERNEL__
+
 #undef NULL
-#if defined(__cplusplus)
-#define NULL 0
-#else
 #define NULL ((void *)0)
-#endif
-
-#ifdef __KERNEL__
 
 enum {
 	false	= 0,
-- 
1.7.3.4
-- 
 Lubos Lunak
 l.lunak@...e.cz
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