[PATCH 3.10 216/319] drivers/vfio: Rework offsetofend()

Willy Tarreau
2017-02-05T19:37:24Z

From: Gavin Shan <gwshan@linux.vnet.ibm.com>

commit b13460b92093b29347e99d6c3242e350052b62cd upstream.

The macro offsetofend() introduces unnecessary temporary variable
"tmp". The patch avoids that and saves a bit memory in stack.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
[wt: backported only for ipv6 out-of-bounds fix]

Signed-off-by: Willy Tarreau <w@1wt.eu>
---
include/linux/vfio.h | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index ac8d488..1a7f0ac 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -86,8 +86,7 @@ extern void vfio_unregister_iommu_driver(
* from user space. This allows us to easily determine if the provided
* structure is sized to include various fields.
*/
-#define offsetofend(TYPE, MEMBER) ({ \
- TYPE tmp; \
- offsetof(TYPE, MEMBER) + sizeof(tmp.MEMBER); }) \
+#define offsetofend(TYPE, MEMBER) \
+ (offsetof(TYPE, MEMBER) + sizeof(((TYPE *)0)->MEMBER))

#endif /* VFIO_H */
--
2.8.0.rc2.1.gbe9624a