Re: [PATCH rdma-next v2] RDMA/nldev: add resource summary max values for usage display

[Leon Romanovsky <leon@kernel.org>]

On Fri, May 15, 2026 at 03:33:07PM +0800, Tao Cui wrote:
> Add RDMA_NLDEV_ATTR_RES_SUMMARY_ENTRY_MAX netlink attribute to expose
> device resource limits (max_qp, max_cq, max_mr, max_pd, max_srq) in
> the resource summary alongside the existing current count. This allows
> userspace tools like iproute2's rdma to display resource usage in
> curr/max format.
> 
> Expected output from "rdma resource show":
>   Before: 0: mlx5_0: qp 123  cq 45  mr 200  pd 10
>   After:  0: mlx5_0: qp 123/131072  cq 45/65536  mr 200/1000000  pd 10/32768
> 
> In JSON output, both "curr" and "max" fields will be provided so that
> scripts can compute percentages if needed.
> 
> The new attribute is optional and backward compatible - old userspace
> tools will simply ignore it.
> 
> Signed-off-by: Tao Cui <cuitao@kylinos.cn>
> ---
>  drivers/infiniband/core/nldev.c  | 29 ++++++++++++++++++++++++++---
>  include/uapi/rdma/rdma_netlink.h |  5 +++++
>  2 files changed, 31 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/infiniband/core/nldev.c b/drivers/infiniband/core/nldev.c
> index 96c745d5bac4..879aaa7960fe 100644
> --- a/drivers/infiniband/core/nldev.c
> +++ b/drivers/infiniband/core/nldev.c
> @@ -187,6 +187,7 @@ static const struct nla_policy nldev_policy[RDMA_NLDEV_ATTR_MAX] = {
>  	[RDMA_NLDEV_ATTR_FRMR_POOLS_AGING_PERIOD] = { .type = NLA_U32 },
>  	[RDMA_NLDEV_ATTR_FRMR_POOL_PINNED_HANDLES] = { .type = NLA_U32 },
>  	[RDMA_NLDEV_ATTR_FRMR_POOL_KEY_KERNEL_VENDOR_KEY] = { .type = NLA_U64 },
> +	[RDMA_NLDEV_ATTR_RES_SUMMARY_ENTRY_MAX]	= { .type = NLA_U64 },
>  };

<...>

>  	if (fill_nldev_handle(msg, device))
>  		return -EMSGSIZE;
> @@ -462,7 +466,26 @@ static int fill_res_info(struct sk_buff *msg, struct ib_device *device,
>  		if (!names[i])
>  			continue;
>  		curr = rdma_restrack_count(device, i, show_details);
> -		ret = fill_res_info_entry(msg, names[i], curr);
> +		switch (i) {
> +		case RDMA_RESTRACK_QP:
> +			max = device->attrs.max_qp;
> +			break;
> +		case RDMA_RESTRACK_CQ:
> +			max = device->attrs.max_cq;
> +			break;
> +		case RDMA_RESTRACK_MR:
> +			max = device->attrs.max_mr;
> +			break;
> +		case RDMA_RESTRACK_PD:
> +			max = device->attrs.max_pd;
> +			break;
> +		case RDMA_RESTRACK_SRQ:
> +			max = device->attrs.max_srq;
> +			break;
> +		default:
> +			max = 0;

The more accurate approach is to avoid setting the  
RDMA_NLDEV_ATTR_RES_SUMMARY_ENTRY_MAX field for cases that have no  
limitations, and let iproute2 decide how to handle it.

Thanks