From: Jason Gunthorpe Date: Fri, 3 Sep 2021 13:07:28 +0000 (-0300) Subject: IB/qib: Fix null pointer subtraction compiler warning X-Git-Tag: microblaze-v5.16~47^2~2 X-Git-Url: http://git.monstr.eu/?p=linux-2.6-microblaze.git;a=commitdiff_plain;h=84f969e1c48ed3825986e91a0786e363d57f69d1;hp=f4c6f31011eafe027abddf6cee1288a1b5a05b73 IB/qib: Fix null pointer subtraction compiler warning >> drivers/infiniband/hw/qib/qib_sysfs.c:411:1: warning: performing pointer subtraction with a null pointer has undefined behavior +[-Wnull-pointer-subtraction] QIB_DIAGC_ATTR(rc_resends); ^~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/infiniband/hw/qib/qib_sysfs.c:408:51: note: expanded from macro 'QIB_DIAGC_ATTR' .counter = &((struct qib_ibport *)0)->rvp.n_##N - (u64 *)0, \ Use offsetof and accomplish the type check using static_assert. Fixes: 4a7aaf88c89f ("RDMA/qib: Use attributes for the port sysfs") Link: https://lore.kernel.org/r/0-v1-43ae3c759177+65-qib_type_jgg@nvidia.com Reported-by: kernel test robot Acked-by: Dennis Dalessandro Signed-off-by: Jason Gunthorpe --- diff --git a/drivers/infiniband/hw/qib/qib_sysfs.c b/drivers/infiniband/hw/qib/qib_sysfs.c index d57e49de6650..452e2355d24e 100644 --- a/drivers/infiniband/hw/qib/qib_sysfs.c +++ b/drivers/infiniband/hw/qib/qib_sysfs.c @@ -403,9 +403,11 @@ static ssize_t diagc_attr_store(struct ib_device *ibdev, u32 port_num, } #define QIB_DIAGC_ATTR(N) \ + static_assert(&((struct qib_ibport *)0)->rvp.n_##N != (u64 *)NULL); \ static struct qib_diagc_attr qib_diagc_attr_##N = { \ .attr = __ATTR(N, 0664, diagc_attr_show, diagc_attr_store), \ - .counter = &((struct qib_ibport *)0)->rvp.n_##N - (u64 *)0, \ + .counter = \ + offsetof(struct qib_ibport, rvp.n_##N) / sizeof(u64) \ } QIB_DIAGC_ATTR(rc_resends);