[PATCH] ERR_PTR: warn when ERR_PTR parameter is valid argument

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

Check at runtime whether error argument of ERR_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.

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Johannes Weiner <hannes@saeurebad.de>
---
 include/linux/err.h |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/include/linux/err.h b/include/linux/err.h
index 4773ed3..f7e098e 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>
 
 /*
@@ -22,6 +23,7 @@
 
 static inline void *__ERR_PTR(long error)
 {
+	WARN_ON(!VALID_ERR_PTR_ARG(error));
 	return (void *) error;
 }
 
-- 
1.5.4.5