On Fri, Feb 02, 2018 at 04:46:30PM +0100, Arnd Bergmann wrote:
> gcc-8 notices that the memcpy in mlx5_core_query_xsrq() makes no
> sense because the source and destination variables are identical:
>
> drivers/net/ethernet/mellanox/mlx5/core/transobj.c: In function 'mlx5_core_query_xsrq':
> drivers/net/ethernet/mellanox/mlx5/core/transobj.c:347:3: error: 'memcpy' source argument is the same as destination [-Werror=restrict]
>
> Either one of the pointers should be something else, or the code is
> completely bogus. Removing the memcpy() won't change the behavior
> but gets rid of the warning.
>
> Fixes: 01949d0109ee ("net/mlx5_core: Enable XRCs and SRQs when using ISSI > 0")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> Please review carefully, I have no idea what the author actually
> intended here.
I think they intended to adjust the command return between
mlx5_ifc_query_srq_out_bits and mlx5_ifc_query_xrc_srq_out_bits?
> index 9e38343a951f..75450f7d53bf 100644
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/transobj.c
> @@ -332,20 +332,12 @@ int mlx5_core_destroy_xsrq(struct mlx5_core_dev *dev, u32 xsrqn)
> int mlx5_core_query_xsrq(struct mlx5_core_dev *dev, u32 xsrqn, u32 *out)
> {
> u32 in[MLX5_ST_SZ_DW(query_xrc_srq_in)] = {0};
> - void *srqc;
> - void *xrc_srqc;
> int err;
>
> MLX5_SET(query_xrc_srq_in, in, opcode, MLX5_CMD_OP_QUERY_XRC_SRQ);
> MLX5_SET(query_xrc_srq_in, in, xrc_srqn, xsrqn);
> err = mlx5_cmd_exec(dev, in, sizeof(in), out,
> MLX5_ST_SZ_BYTES(query_xrc_srq_out));
> - if (!err) {
> - xrc_srqc = MLX5_ADDR_OF(query_xrc_srq_out, out,
> - xrc_srq_context_entry);
> - srqc = MLX5_ADDR_OF(query_srq_out, out, srq_context_entry);
> - memcpy(srqc, xrc_srqc, MLX5_ST_SZ_BYTES(srqc));
> - }
Probably should add a
BUILD_BUG_ON(MLX5_BYTE_OFF(query_xrc_srq_out, xrc_srq_context_entry) == MLX5_BYTE_OFF(query_srq_out, srq_context_entry));
Just for clarity that the SRQ and XRC_SRQ are being used interchangeably.
and the 'err' variable can be eliminated.
Curious though that I can't find a call site for it, and removing the
prototype doesn't break the build.. Seems like dead code.
Jason
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