net/mlx5e: Fix build warning, detected write beyond size of field

When merged with Linus tree, the cited patch below will cause the
following build warning:

In function 'fortify_memset_chk',
    inlined from 'mlx5e_xmit_xdp_frame' at drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c:438:3:
include/linux/fortify-string.h:242:25: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning]
  242 |                         __write_overflow_field(p_size_field, size);
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fix that by grouping the fields to memeset in struct_group() to avoid
the false alarm.

Fixes: 9ded70fa1d81 ("net/mlx5e: Don't prefill WQEs in XDP SQ in the multi buffer mode")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Suggested-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Link: https://lore.kernel.org/r/20220322172224.31849-1-saeed@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
index f35b62c..8f321a6 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
@@ -435,8 +435,7 @@ mlx5e_xmit_xdp_frame(struct mlx5e_xdpsq *sq, struct mlx5e_xmit_data *xdptxd,
                u8 num_pkts = 1 + num_frags;
                int i;
 
-               memset(&cseg->signature, 0, sizeof(*cseg) -
-                      sizeof(cseg->opmod_idx_opcode) - sizeof(cseg->qpn_ds));
+               memset(&cseg->trailer, 0, sizeof(cseg->trailer));
                memset(eseg, 0, sizeof(*eseg) - sizeof(eseg->trailer));
 
                eseg->inline_hdr.sz = cpu_to_be16(inline_hdr_sz);

diff --git a/include/linux/mlx5/qp.h b/include/linux/mlx5/qp.h
index 61e48d4..8bda3ba 100644 (file)
--- a/include/linux/mlx5/qp.h
+++ b/include/linux/mlx5/qp.h
@@ -202,6 +202,9 @@ struct mlx5_wqe_fmr_seg {
 struct mlx5_wqe_ctrl_seg {
        __be32                  opmod_idx_opcode;
        __be32                  qpn_ds;
+
+       struct_group(trailer,
+
        u8                      signature;
        u8                      rsvd[2];
        u8                      fm_ce_se;
@@ -211,6 +214,8 @@ struct mlx5_wqe_ctrl_seg {
                __be32          umr_mkey;
                __be32          tis_tir_num;
        };
+
+       ); /* end of trailer group */
 };
 
 #define MLX5_WQE_CTRL_DS_MASK 0x3f