Re: [PATCH 1/2] RDMA/nldev: add resource summary max values for usage rate display

[Leon Romanovsky <leon@kernel.org>]

On Thu, Apr 23, 2026 at 02:13:51PM +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 rates.

Historically, we try to avoid duplicating functionality, and this already
exists in ibv_devinfo. What is the reason for adding it to rdmatool as well?

> 
> 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 },
>  };
>  
>  static int put_driver_name_print_type(struct sk_buff *msg, const char *name,
> @@ -412,7 +413,7 @@ static int fill_port_info(struct sk_buff *msg,
>  }
>  
>  static int fill_res_info_entry(struct sk_buff *msg,
> -			       const char *name, u64 curr)
> +			       const char *name, u64 curr, u64 max)
>  {
>  	struct nlattr *entry_attr;
>  
> @@ -426,6 +427,9 @@ static int fill_res_info_entry(struct sk_buff *msg,
>  	if (nla_put_u64_64bit(msg, RDMA_NLDEV_ATTR_RES_SUMMARY_ENTRY_CURR, curr,
>  			      RDMA_NLDEV_ATTR_PAD))
>  		goto err;
> +	if (nla_put_u64_64bit(msg, RDMA_NLDEV_ATTR_RES_SUMMARY_ENTRY_MAX, max,
> +			      RDMA_NLDEV_ATTR_PAD))
> +		goto err;

From an implementation perspective, this is not an appropriate place to
store this information. It will result in reporting the same value
(max_XXX is per‑device) across multiple objects.

Thanks