Re: [RFC PATCH 2/3] RDMA/uverbs: Add uverbs commands for fd-based MR registration

[Jason Gunthorpe <jgg@ziepe.ca>]

On Thu, Apr 16, 2020 at 10:09:32AM -0700, Jianxin Xiong wrote:

> diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
> index f6c2552..b3f7261 100644
> --- a/drivers/infiniband/core/device.c
> +++ b/drivers/infiniband/core/device.c
> @@ -2654,9 +2654,11 @@ void ib_set_device_ops(struct ib_device *dev, const struct ib_device_ops *ops)
>  	SET_DEVICE_OP(dev_ops, read_counters);
>  	SET_DEVICE_OP(dev_ops, reg_dm_mr);
>  	SET_DEVICE_OP(dev_ops, reg_user_mr);
> +	SET_DEVICE_OP(dev_ops, reg_user_mr_fd);
>  	SET_DEVICE_OP(dev_ops, req_ncomp_notif);
>  	SET_DEVICE_OP(dev_ops, req_notify_cq);
>  	SET_DEVICE_OP(dev_ops, rereg_user_mr);
> +	SET_DEVICE_OP(dev_ops, rereg_user_mr_fd);

I'm not so found of adding such a specific callback.. It seems better
to have a generic reg_user_mr that accepts a ib_umem created by the
core code. Burying the umem_get in the drivers was probably a mistake.

>  static int ib_uverbs_dereg_mr(struct uverbs_attr_bundle *attrs)
>  {
>  	struct ib_uverbs_dereg_mr cmd;
> @@ -3916,7 +4081,19 @@ static int ib_uverbs_ex_modify_cq(struct uverbs_attr_bundle *attrs)
>  			ib_uverbs_rereg_mr,
>  			UAPI_DEF_WRITE_UDATA_IO(struct ib_uverbs_rereg_mr,
>  						struct ib_uverbs_rereg_mr_resp),
> -			UAPI_DEF_METHOD_NEEDS_FN(rereg_user_mr))),
> +			UAPI_DEF_METHOD_NEEDS_FN(rereg_user_mr)),
> +		DECLARE_UVERBS_WRITE(
> +			IB_USER_VERBS_CMD_REG_MR_FD,
> +			ib_uverbs_reg_mr_fd,
> +			UAPI_DEF_WRITE_UDATA_IO(struct ib_uverbs_reg_mr_fd,
> +						struct ib_uverbs_reg_mr_resp),
> +			UAPI_DEF_METHOD_NEEDS_FN(reg_user_mr_fd)),
> +		DECLARE_UVERBS_WRITE(
> +			IB_USER_VERBS_CMD_REREG_MR_FD,
> +			ib_uverbs_rereg_mr_fd,
> +			UAPI_DEF_WRITE_UDATA_IO(struct ib_uverbs_rereg_mr_fd,
> +						struct ib_uverbs_rereg_mr_resp),
> +			UAPI_DEF_METHOD_NEEDS_FN(rereg_user_mr_fd))),

New write based methods are not allowed, they have to be done as ioctl
methods.

Jason