[PATCH 6/6] ERR_PTR: warn when ERR_PTR parameter is not errno value

[Marcin Slusarz <marcin.slusarz@gmail.com>]

Check at runtime whether error argument of ERR_PTR and ERR_OR_0_PTR
is valid. It can catch bugs which possibly lead to oops or panic earlier.

Currently there are > 600 calls of ERR_PTR with non-constant argument
in Linux kernel sources.

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 include/linux/err.h |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/include/linux/err.h b/include/linux/err.h
index cdec8b6..51e2459 100644
--- a/include/linux/err.h
+++ b/include/linux/err.h
@@ -3,6 +3,7 @@
 
 #include <linux/compiler.h>
 
+#include <asm/bug.h>
 #include <asm/errno.h>
 
 /*
@@ -21,6 +22,7 @@
 
 static inline void *__ERR_PTR(long error)
 {
+	WARN_ON(!IS_ERR_VALUE(error));
 	return (void *) error;
 }
 
@@ -28,6 +30,7 @@ static inline void *__ERR_PTR(long error)
 
 static inline void *__ERR_OR_0_PTR(long error)
 {
+	WARN_ON(!IS_ERR_VALUE(error) && error);
 	return (void *) error;
 }
 
-- 
1.5.4.5