This is a note to let you know that I've just added the patch titled IB/qib: Fix null pointer subtraction compiler warning to the 5.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ib-qib-fix-null-pointer-subtraction-compiler-warning.patch and it can be found in the queue-5.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 404d8ee4fb767e1c2a19d57fb7e3a5b944bedb0b Author: Jason Gunthorpe <jgg@xxxxxxxxxx> Date: Fri Sep 3 10:07:28 2021 -0300 IB/qib: Fix null pointer subtraction compiler warning [ Upstream commit 84f969e1c48ed3825986e91a0786e363d57f69d1 ] >> 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@xxxxxxxxxx Reported-by: kernel test robot <lkp@xxxxxxxxx> Acked-by: Dennis Dalessandro <dennis.dalessandro@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> 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);