On Fri, Feb 2, 2018 at 8:06 PM, Jason Gunthorpe <jgg@xxxxxxxxxxxx> wrote: > 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. I checked the git history and don't see any user ever added after the function first showed up in the kernel, same for a couple of other functions from commit 01949d0109ee ("net/mlx5_core: Enable XRCs and SRQs when using ISSI > 0"). Can you come up with a proper patch for this isse, either removing the dead code, or fixing it appropriately? You clearly understand what this file is about, and I don't ;-) Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html