[PATCH 3.19 172/175] kernel: Fix sparse warning for ACCESS_ONCE

Greg Kroah-Hartman
2015-03-04T06:22:23Z

From: Christian Borntraeger <borntraeger@de.ibm.com>

commit c5b19946eb76c67566aae6a84bf2b10ad59295ea upstream.

Commit 927609d622a3 ("kernel: tighten rules for ACCESS ONCE") results in
sparse warnings like "Using plain integer as NULL pointer" - Let's add a
type cast to the dummy assignment.
To avoid warnings lik "sparse: warning: cast to restricted __hc32" we also
use __force on that cast.

Fixes: 927609d622a3 ("kernel: tighten rules for ACCESS ONCE")
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
include/linux/compiler.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -461,7 +461,7 @@ static __always_inline void __write_once
* If possible use READ_ONCE/ASSIGN_ONCE instead.
*/
#define __ACCESS_ONCE(x) ({ \
- __maybe_unused typeof(x) __var = 0; \
+ __maybe_unused typeof(x) __var = (__force typeof(x)) 0; \
(volatile typeof(x) *)&(x); })
#define ACCESS_ONCE(x) (*__ACCESS_ONCE(x))