[PATCH 2/6] ERR_PTR: add ERR_OR_0_PTR

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

Some codepaths call ERR_PTR with possibly 0 argument, which is not
a valid errno and rely on conversion from 0 to NULL pointer.
Add ERR_OR_0_PTR function which accepts errnos and 0 as an argument.

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 include/linux/err.h |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/include/linux/err.h b/include/linux/err.h
index 7b5daa6..cdec8b6 100644
--- a/include/linux/err.h
+++ b/include/linux/err.h
@@ -26,6 +26,13 @@ static inline void *__ERR_PTR(long error)
 
 #define ERR_PTR(error) (BUILD_BUG_ON(__builtin_constant_p(error) && !IS_ERR_VALUE(error)), __ERR_PTR(error))
 
+static inline void *__ERR_OR_0_PTR(long error)
+{
+	return (void *) error;
+}
+
+#define ERR_OR_0_PTR(error) (BUILD_BUG_ON(__builtin_constant_p(error) && error && !IS_ERR_VALUE(error)), __ERR_OR_0_PTR(error))
+
 static inline long PTR_ERR(const void *ptr)
 {
 	return (long) ptr;
-- 
1.5.4.5