From: Saeed Mahameed <saeedm@nvidia.com>

Devlink param value attribute is not defined since devlink is handling
the value validating and parsing internally, this allows us to implement
multi attribute values without breaking any policies.

Devlink param multi-attribute values are considered to be dynamically
sized arrays of u64 values, by introducing a new devlink param type
DEVLINK_PARAM_TYPE_U64_ARRAY, driver and user space can set a variable
count of u32 values into the DEVLINK_ATTR_PARAM_VALUE_DATA attribute.

Implement get/set parsing and add to the internal value structure passed
to drivers.

This is useful for devices that need to configure a list of values for
a specific configuration.

example:
$ devlink dev param show pci/... name multi-value-param
name multi-value-param type driver-specific
values:
cmode permanent value: 0,1,2,3,4,5,6,7

$ devlink dev param set pci/... name multi-value-param \
		value 4,5,6,7,0,1,2,3 cmode permanent

Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Ratheesh Kannoth <rkannoth@marvell.com>
---
 Documentation/netlink/specs/devlink.yaml |  4 ++
 include/net/devlink.h                    |  8 +++
 include/uapi/linux/devlink.h             |  1 +
 net/devlink/netlink_gen.c                |  2 +
 net/devlink/param.c                      | 70 ++++++++++++++++++++----
 5 files changed, 74 insertions(+), 11 deletions(-)

diff --git a/Documentation/netlink/specs/devlink.yaml b/Documentation/netlink/specs/devlink.yaml
index b495d56b9137..b619de4fe08a 100644
--- a/Documentation/netlink/specs/devlink.yaml
+++ b/Documentation/netlink/specs/devlink.yaml
@@ -226,6 +226,10 @@ definitions:
         value: 10
       -
         name: binary
+      -
+        name: u64-array
+        value: 129
+
   -
     name: rate-tc-index-max
     type: const
diff --git a/include/net/devlink.h b/include/net/devlink.h
index 3038af6ec017..3a355fea8189 100644
--- a/include/net/devlink.h
+++ b/include/net/devlink.h
@@ -432,6 +432,13 @@ enum devlink_param_type {
 	DEVLINK_PARAM_TYPE_U64 = DEVLINK_VAR_ATTR_TYPE_U64,
 	DEVLINK_PARAM_TYPE_STRING = DEVLINK_VAR_ATTR_TYPE_STRING,
 	DEVLINK_PARAM_TYPE_BOOL = DEVLINK_VAR_ATTR_TYPE_FLAG,
+	DEVLINK_PARAM_TYPE_U64_ARRAY = DEVLINK_VAR_ATTR_TYPE_U64_ARRAY,
+};
+
+#define __DEVLINK_PARAM_MAX_ARRAY_SIZE 32
+struct devlink_param_u64_array {
+	u64 size;
+	u64 val[__DEVLINK_PARAM_MAX_ARRAY_SIZE];
 };
 
 union devlink_param_value {
@@ -441,6 +448,7 @@ union devlink_param_value {
 	u64 vu64;
 	char vstr[__DEVLINK_PARAM_MAX_STRING_VALUE];
 	bool vbool;
+	struct devlink_param_u64_array u64arr;
 };
 
 struct devlink_param_gset_ctx {
diff --git a/include/uapi/linux/devlink.h b/include/uapi/linux/devlink.h
index 7de2d8cc862f..5332223dd6d0 100644
--- a/include/uapi/linux/devlink.h
+++ b/include/uapi/linux/devlink.h
@@ -406,6 +406,7 @@ enum devlink_var_attr_type {
 	DEVLINK_VAR_ATTR_TYPE_BINARY,
 	__DEVLINK_VAR_ATTR_TYPE_CUSTOM_BASE = 0x80,
 	/* Any possible custom types, unrelated to NLA_* values go below */
+	DEVLINK_VAR_ATTR_TYPE_U64_ARRAY,
 };
 
 enum devlink_attr {
diff --git a/net/devlink/netlink_gen.c b/net/devlink/netlink_gen.c
index eb35e80e01d1..7aaf462f27ee 100644
--- a/net/devlink/netlink_gen.c
+++ b/net/devlink/netlink_gen.c
@@ -37,6 +37,8 @@ devlink_attr_param_type_validate(const struct nlattr *attr,
 	case DEVLINK_VAR_ATTR_TYPE_NUL_STRING:
 		fallthrough;
 	case DEVLINK_VAR_ATTR_TYPE_BINARY:
+		fallthrough;
+	case DEVLINK_VAR_ATTR_TYPE_U64_ARRAY:
 		return 0;
 	}
 	NL_SET_ERR_MSG_ATTR(extack, attr, "invalid enum value");
diff --git a/net/devlink/param.c b/net/devlink/param.c
index cf95268da5b0..0342697fd231 100644
--- a/net/devlink/param.c
+++ b/net/devlink/param.c
@@ -252,6 +252,14 @@ devlink_nl_param_value_put(struct sk_buff *msg, enum devlink_param_type type,
 				return -EMSGSIZE;
 		}
 		break;
+	case DEVLINK_PARAM_TYPE_U64_ARRAY:
+		if (val.u64arr.size > __DEVLINK_PARAM_MAX_ARRAY_SIZE)
+			return -EMSGSIZE;
+
+		for (int i = 0; i < val.u64arr.size; i++)
+			if (nla_put_uint(msg, nla_type, val.u64arr.val[i]))
+				return -EMSGSIZE;
+		break;
 	}
 	return 0;
 }
@@ -304,11 +312,11 @@ static int devlink_nl_param_fill(struct sk_buff *msg, struct devlink *devlink,
 				 u32 portid, u32 seq, int flags,
 				 struct netlink_ext_ack *extack)
 {
-	union devlink_param_value default_value[DEVLINK_PARAM_CMODE_MAX + 1];
-	union devlink_param_value param_value[DEVLINK_PARAM_CMODE_MAX + 1];
 	bool default_value_set[DEVLINK_PARAM_CMODE_MAX + 1] = {};
 	bool param_value_set[DEVLINK_PARAM_CMODE_MAX + 1] = {};
 	const struct devlink_param *param = param_item->param;
+	union devlink_param_value *default_value;
+	union devlink_param_value *param_value;
 	struct devlink_param_gset_ctx ctx;
 	struct nlattr *param_values_list;
 	struct nlattr *param_attr;
@@ -316,17 +324,31 @@ static int devlink_nl_param_fill(struct sk_buff *msg, struct devlink *devlink,
 	int err;
 	int i;
 
+	default_value = kcalloc(DEVLINK_PARAM_CMODE_MAX + 1,
+				sizeof(*default_value), GFP_KERNEL);
+	if (!default_value)
+		return -ENOMEM;
+
+	param_value = kcalloc(DEVLINK_PARAM_CMODE_MAX + 1,
+			      sizeof(*param_value), GFP_KERNEL);
+	if (!param_value) {
+		kfree(default_value);
+		return -ENOMEM;
+	}
+
 	/* Get value from driver part to driverinit configuration mode */
 	for (i = 0; i <= DEVLINK_PARAM_CMODE_MAX; i++) {
 		if (!devlink_param_cmode_is_supported(param, i))
 			continue;
 		if (i == DEVLINK_PARAM_CMODE_DRIVERINIT) {
-			if (param_item->driverinit_value_new_valid)
+			if (param_item->driverinit_value_new_valid) {
 				param_value[i] = param_item->driverinit_value_new;
-			else if (param_item->driverinit_value_valid)
+			} else if (param_item->driverinit_value_valid) {
 				param_value[i] = param_item->driverinit_value;
-			else
-				return -EOPNOTSUPP;
+			} else {
+				err = -EOPNOTSUPP;
+				goto get_put_fail;
+			}
 
 			if (param_item->driverinit_value_valid) {
 				default_value[i] = param_item->driverinit_default;
@@ -336,7 +358,7 @@ static int devlink_nl_param_fill(struct sk_buff *msg, struct devlink *devlink,
 			ctx.cmode = i;
 			err = devlink_param_get(devlink, param, &ctx, extack);
 			if (err)
-				return err;
+				goto get_put_fail;
 			param_value[i] = ctx.val;
 
 			err = devlink_param_get_default(devlink, param, &ctx,
@@ -345,15 +367,16 @@ static int devlink_nl_param_fill(struct sk_buff *msg, struct devlink *devlink,
 				default_value[i] = ctx.val;
 				default_value_set[i] = true;
 			} else if (err != -EOPNOTSUPP) {
-				return err;
+				goto get_put_fail;
 			}
 		}
 		param_value_set[i] = true;
 	}
 
+	err = -EMSGSIZE;
 	hdr = genlmsg_put(msg, portid, seq, &devlink_nl_family, flags, cmd);
 	if (!hdr)
-		return -EMSGSIZE;
+		goto get_put_fail;
 
 	if (devlink_nl_put_handle(msg, devlink))
 		goto genlmsg_cancel;
@@ -393,6 +416,8 @@ static int devlink_nl_param_fill(struct sk_buff *msg, struct devlink *devlink,
 	nla_nest_end(msg, param_values_list);
 	nla_nest_end(msg, param_attr);
 	genlmsg_end(msg, hdr);
+	kfree(default_value);
+	kfree(param_value);
 	return 0;
 
 values_list_nest_cancel:
@@ -401,7 +426,10 @@ static int devlink_nl_param_fill(struct sk_buff *msg, struct devlink *devlink,
 	nla_nest_cancel(msg, param_attr);
 genlmsg_cancel:
 	genlmsg_cancel(msg, hdr);
-	return -EMSGSIZE;
+get_put_fail:
+	kfree(default_value);
+	kfree(param_value);
+	return err;
 }
 
 static void devlink_param_notify(struct devlink *devlink,
@@ -507,7 +535,7 @@ devlink_param_value_get_from_info(const struct devlink_param *param,
 				  union devlink_param_value *value)
 {
 	struct nlattr *param_data;
-	int len;
+	int len, cnt, rem;
 
 	param_data = info->attrs[DEVLINK_ATTR_PARAM_VALUE_DATA];
 
@@ -547,6 +575,26 @@ devlink_param_value_get_from_info(const struct devlink_param *param,
 			return -EINVAL;
 		value->vbool = nla_get_flag(param_data);
 		break;
+
+	case DEVLINK_PARAM_TYPE_U64_ARRAY:
+		cnt = 0;
+		nla_for_each_attr_type(param_data,
+				       DEVLINK_ATTR_PARAM_VALUE_DATA,
+				       genlmsg_data(info->genlhdr),
+				       genlmsg_len(info->genlhdr), rem) {
+			if (cnt >= __DEVLINK_PARAM_MAX_ARRAY_SIZE)
+				return -EMSGSIZE;
+
+			if ((nla_len(param_data) != sizeof(u64)) &&
+			    (nla_len(param_data) != sizeof(u32)))
+				return -EINVAL;
+
+			value->u64arr.val[cnt] = (u64)nla_get_uint(param_data);
+			cnt++;
+		}
+
+		value->u64arr.size = cnt;
+		break;
 	}
 	return 0;
 }
-- 
2.43.0

Hi Ratheesh,

kernel test robot noticed the following build warnings:

[auto build test WARNING on net-next/main]

url:    https://github.com/intel-lab-lkp/linux/commits/Ratheesh-Kannoth/octeontx2-af-npc-cn20k-debugfs-enhancements/20260320-133513
base:   net-next/main
patch link:    https://lore.kernel.org/r/20260319055533.1720093-3-rkannoth%40marvell.com
patch subject: [PATCH v6 net-next 2/5] devlink: Implement devlink param multi attribute nested data values
config: arm-allyesconfig (https://download.01.org/0day-ci/archive/20260321/202603211533.2z2Lepl1-lkp@intel.com/config)
compiler: arm-linux-gnueabi-gcc (GCC) 15.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260321/202603211533.2z2Lepl1-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202603211533.2z2Lepl1-lkp@intel.com/

All warnings (new ones prefixed by >>):

   drivers/net/ethernet/mellanox/mlx5/core/en/pcie_cong_event.c: In function 'mlx5e_pcie_cong_get_thresh_config':
>> drivers/net/ethernet/mellanox/mlx5/core/en/pcie_cong_event.c:279:1: warning: the frame size of 1320 bytes is larger than 1280 bytes [-Wframe-larger-than=]
     279 | }
         | ^


vim +279 drivers/net/ethernet/mellanox/mlx5/core/en/pcie_cong_event.c

8890ee6dcf6e3d Dragos Tatulea 2025-07-15  250  
f4053490a6f651 Dragos Tatulea 2025-09-07  251  static int
f4053490a6f651 Dragos Tatulea 2025-09-07  252  mlx5e_pcie_cong_get_thresh_config(struct mlx5_core_dev *dev,
f4053490a6f651 Dragos Tatulea 2025-09-07  253  				  struct mlx5e_pcie_cong_thresh *config)
f4053490a6f651 Dragos Tatulea 2025-09-07  254  {
f4053490a6f651 Dragos Tatulea 2025-09-07  255  	u32 ids[4] = {
f4053490a6f651 Dragos Tatulea 2025-09-07  256  		MLX5_DEVLINK_PARAM_ID_PCIE_CONG_IN_LOW,
f4053490a6f651 Dragos Tatulea 2025-09-07  257  		MLX5_DEVLINK_PARAM_ID_PCIE_CONG_IN_HIGH,
f4053490a6f651 Dragos Tatulea 2025-09-07  258  		MLX5_DEVLINK_PARAM_ID_PCIE_CONG_OUT_LOW,
f4053490a6f651 Dragos Tatulea 2025-09-07  259  		MLX5_DEVLINK_PARAM_ID_PCIE_CONG_OUT_HIGH,
f4053490a6f651 Dragos Tatulea 2025-09-07  260  	};
f4053490a6f651 Dragos Tatulea 2025-09-07  261  	struct devlink *devlink = priv_to_devlink(dev);
f4053490a6f651 Dragos Tatulea 2025-09-07  262  	union devlink_param_value val[4];
f4053490a6f651 Dragos Tatulea 2025-09-07  263  
f4053490a6f651 Dragos Tatulea 2025-09-07  264  	for (int i = 0; i < 4; i++) {
f4053490a6f651 Dragos Tatulea 2025-09-07  265  		u32 id = ids[i];
f4053490a6f651 Dragos Tatulea 2025-09-07  266  		int err;
f4053490a6f651 Dragos Tatulea 2025-09-07  267  
f4053490a6f651 Dragos Tatulea 2025-09-07  268  		err = devl_param_driverinit_value_get(devlink, id, &val[i]);
f4053490a6f651 Dragos Tatulea 2025-09-07  269  		if (err)
f4053490a6f651 Dragos Tatulea 2025-09-07  270  			return err;
f4053490a6f651 Dragos Tatulea 2025-09-07  271  	}
f4053490a6f651 Dragos Tatulea 2025-09-07  272  
f4053490a6f651 Dragos Tatulea 2025-09-07  273  	config->inbound_low = val[0].vu16;
f4053490a6f651 Dragos Tatulea 2025-09-07  274  	config->inbound_high = val[1].vu16;
f4053490a6f651 Dragos Tatulea 2025-09-07  275  	config->outbound_low = val[2].vu16;
f4053490a6f651 Dragos Tatulea 2025-09-07  276  	config->outbound_high = val[3].vu16;
f4053490a6f651 Dragos Tatulea 2025-09-07  277  
f4053490a6f651 Dragos Tatulea 2025-09-07  278  	return 0;
f4053490a6f651 Dragos Tatulea 2025-09-07 @279  }
f4053490a6f651 Dragos Tatulea 2025-09-07  280  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki