From 14ab8896f5d993c5f427504276e3c42ccb3cc354 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Mon, 24 Oct 2016 22:48:21 +0200 Subject: [PATCH] IB/mlx5: avoid bogus -Wmaybe-uninitialized warning MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit We get a false-positive warning in linux-next for the mlx5 driver: infiniband/hw/mlx5/mr.c: In function ‘mlx5_ib_reg_user_mr’: infiniband/hw/mlx5/mr.c:1172:5: error: ‘order’ may be used uninitialized in this function [-Werror=maybe-uninitialized] infiniband/hw/mlx5/mr.c:1161:6: note: ‘order’ was declared here infiniband/hw/mlx5/mr.c:1173:6: error: ‘ncont’ may be used uninitialized in this function [-Werror=maybe-uninitialized] infiniband/hw/mlx5/mr.c:1160:6: note: ‘ncont’ was declared here infiniband/hw/mlx5/mr.c:1173:6: error: ‘page_shift’ may be used uninitialized in this function [-Werror=maybe-uninitialized] infiniband/hw/mlx5/mr.c:1158:6: note: ‘page_shift’ was declared here infiniband/hw/mlx5/mr.c:1143:13: error: ‘npages’ may be used uninitialized in this function [-Werror=maybe-uninitialized] infiniband/hw/mlx5/mr.c:1159:6: note: ‘npages’ was declared here I had a trivial workaround for gcc-5 or higher, but that didn't work on gcc-4.9 unfortunately. The only way I found to avoid the warnings for gcc-4.9, short of initializing each of the arguments first was to change the calling conventions to separate the error code from the umem pointer. This avoids casting the error codes from one pointer to another incompatible pointer, and lets gcc figure out when that the data is actually valid whenever we return successfully. Acked-by: Leon Romanovsky Signed-off-by: Arnd Bergmann Signed-off-by: Doug Ledford --- drivers/infiniband/hw/mlx5/mr.c | 39 ++++++++++++++++++--------------- 1 file changed, 21 insertions(+), 18 deletions(-) diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c index 5258ac870e6a..67985c69f9b9 100644 --- a/drivers/infiniband/hw/mlx5/mr.c +++ b/drivers/infiniband/hw/mlx5/mr.c @@ -844,30 +844,34 @@ static void prep_umr_unreg_wqe(struct mlx5_ib_dev *dev, umrwr->mkey = key; } -static struct ib_umem *mr_umem_get(struct ib_pd *pd, u64 start, u64 length, - int access_flags, int *npages, - int *page_shift, int *ncont, int *order) +static int mr_umem_get(struct ib_pd *pd, u64 start, u64 length, + int access_flags, struct ib_umem **umem, + int *npages, int *page_shift, int *ncont, + int *order) { struct mlx5_ib_dev *dev = to_mdev(pd->device); - struct ib_umem *umem = ib_umem_get(pd->uobject->context, start, length, - access_flags, 0); - if (IS_ERR(umem)) { + int err; + + *umem = ib_umem_get(pd->uobject->context, start, length, + access_flags, 0); + err = PTR_ERR_OR_ZERO(*umem); + if (err < 0) { mlx5_ib_err(dev, "umem get failed (%ld)\n", PTR_ERR(umem)); - return (void *)umem; + return err; } - mlx5_ib_cont_pages(umem, start, MLX5_MKEY_PAGE_SHIFT_MASK, npages, + mlx5_ib_cont_pages(*umem, start, MLX5_MKEY_PAGE_SHIFT_MASK, npages, page_shift, ncont, order); if (!*npages) { mlx5_ib_warn(dev, "avoid zero region\n"); - ib_umem_release(umem); - return ERR_PTR(-EINVAL); + ib_umem_release(*umem); + return -EINVAL; } mlx5_ib_dbg(dev, "npages %d, ncont %d, order %d, page_shift %d\n", *npages, *ncont, *order, *page_shift); - return umem; + return 0; } static void mlx5_ib_umr_done(struct ib_cq *cq, struct ib_wc *wc) @@ -1193,11 +1197,11 @@ struct ib_mr *mlx5_ib_reg_user_mr(struct ib_pd *pd, u64 start, u64 length, mlx5_ib_dbg(dev, "start 0x%llx, virt_addr 0x%llx, length 0x%llx, access_flags 0x%x\n", start, virt_addr, length, access_flags); - umem = mr_umem_get(pd, start, length, access_flags, &npages, + err = mr_umem_get(pd, start, length, access_flags, &umem, &npages, &page_shift, &ncont, &order); - if (IS_ERR(umem)) - return (void *)umem; + if (err < 0) + return ERR_PTR(err); if (use_umr(order)) { mr = reg_umr(pd, umem, virt_addr, length, ncont, page_shift, @@ -1371,10 +1375,9 @@ int mlx5_ib_rereg_user_mr(struct ib_mr *ib_mr, int flags, u64 start, */ flags |= IB_MR_REREG_TRANS; ib_umem_release(mr->umem); - mr->umem = mr_umem_get(pd, addr, len, access_flags, &npages, - &page_shift, &ncont, &order); - if (IS_ERR(mr->umem)) { - err = PTR_ERR(mr->umem); + err = mr_umem_get(pd, addr, len, access_flags, &mr->umem, + &npages, &page_shift, &ncont, &order); + if (err < 0) { mr->umem = NULL; return err; } -- 2.20.1