[PATCH iproute2-next v7 2/2] rdma: display resource limits in curr/max format

[Tao Cui <cui.tao@linux.dev>]

From: Tao Cui <cuitao@kylinos.cn>

Parse the new RDMA_NLDEV_ATTR_RES_SUMMARY_ENTRY_MAX netlink attribute
to show resource limits alongside current counts in curr/max format:

  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

JSON output provides separate <name> and <name>-max fields per resource
type, so scripts can compute usage against the device limit; resources
without an upper bound (e.g. cm_id, ctx) are reported without a -max
field:

  $ rdma resource show -j
  [{
      "ifindex": 0,
      "ifname": "mlx5_0",
      "qp": 123, "qp-max": 131072,
      "cq": 45, "cq-max": 65536,
      "mr": 200, "mr-max": 1000000,
      "pd": 10, "pd-max": 32768,
      "cm_id": 0, "ctx": 0
  }]

Backward compatible: no output change when the kernel lacks the new
attribute.

Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Link: https://lore.kernel.org/all/20260615003646.168704-1-cui.tao@linux.dev/
---
 rdma/res.c   | 16 +++++++++++++++-
 rdma/utils.c |  1 +
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/rdma/res.c b/rdma/res.c
index 062f0007..7efced8d 100644
--- a/rdma/res.c
+++ b/rdma/res.c
@@ -55,7 +55,21 @@ static int res_print_summary(struct nlattr **tb)
 
 		name = mnl_attr_get_str(nla_line[RDMA_NLDEV_ATTR_RES_SUMMARY_ENTRY_NAME]);
 		curr = mnl_attr_get_u64(nla_line[RDMA_NLDEV_ATTR_RES_SUMMARY_ENTRY_CURR]);
-		res_print_u64(name, curr, nla_line[RDMA_NLDEV_ATTR_RES_SUMMARY_ENTRY_CURR]);
+		if (nla_line[RDMA_NLDEV_ATTR_RES_SUMMARY_ENTRY_MAX]) {
+			uint64_t max;
+			char max_name[64];
+
+			max = mnl_attr_get_u64(
+				nla_line[RDMA_NLDEV_ATTR_RES_SUMMARY_ENTRY_MAX]);
+			snprintf(max_name, sizeof(max_name), "%s-max", name);
+			print_u64(PRINT_JSON, name, NULL, curr);
+			print_u64(PRINT_JSON, max_name, NULL, max);
+			if (!is_json_context())
+				pr_out("%s %" PRIu64 "/%" PRIu64 " ", name, curr, max);
+		} else {
+			res_print_u64(name, curr,
+				      nla_line[RDMA_NLDEV_ATTR_RES_SUMMARY_ENTRY_CURR]);
+		}
 	}
 	return 0;
 }
diff --git a/rdma/utils.c b/rdma/utils.c
index 87003b2c..90ea1c55 100644
--- a/rdma/utils.c
+++ b/rdma/utils.c
@@ -480,6 +480,7 @@ static const enum mnl_attr_data_type nldev_policy[RDMA_NLDEV_ATTR_MAX] = {
 	[RDMA_NLDEV_ATTR_EVENT_TYPE] = MNL_TYPE_U8,
 	[RDMA_NLDEV_SYS_ATTR_MONITOR_MODE] = MNL_TYPE_U8,
 	[RDMA_NLDEV_ATTR_STAT_OPCOUNTER_ENABLED] = MNL_TYPE_U8,
+	[RDMA_NLDEV_ATTR_RES_SUMMARY_ENTRY_MAX] = MNL_TYPE_U64,
 };
 
 static int rd_attr_check(const struct nlattr *attr, int *typep)
-- 
2.43.0