[PATCH net-next] devlink: Implement devlink param multi attribute nested data values

[Ratheesh Kannoth <rkannoth@marvell.com>]

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 u32 values, by introducing a new devlink param type
DEVLINK_PARAM_TYPE_U32_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                      | 18 +++++++++++++++++-
 5 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/Documentation/netlink/specs/devlink.yaml b/Documentation/netlink/specs/devlink.yaml
index 837112da6738..e8a8287c4f19 100644
--- a/Documentation/netlink/specs/devlink.yaml
+++ b/Documentation/netlink/specs/devlink.yaml
@@ -226,6 +226,10 @@ definitions:
         value: 10
       -
         name: binary
+      -
+        name: u32-array
+        value: 129
+
   -
     name: rate-tc-index-max
     type: const
diff --git a/include/net/devlink.h b/include/net/devlink.h
index cb839e0435a1..0a496715da99 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_U32_ARRAY = DEVLINK_VAR_ATTR_TYPE_U32_ARRAY,
+};
+
+#define __DEVLINK_PARAM_MAX_ARRAY_SIZE 32
+struct devlink_param_u32_array {
+	u32 size;
+	u32 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_u32_array u32arr;
 };
 
 struct devlink_param_gset_ctx {
diff --git a/include/uapi/linux/devlink.h b/include/uapi/linux/devlink.h
index e7d6b6d13470..768d0d88710f 100644
--- a/include/uapi/linux/devlink.h
+++ b/include/uapi/linux/devlink.h
@@ -404,6 +404,7 @@ 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_U32_ARRAY,
 };
 
 enum devlink_attr {
diff --git a/net/devlink/netlink_gen.c b/net/devlink/netlink_gen.c
index f4c61c2b4f22..e5a80eb467b8 100644
--- a/net/devlink/netlink_gen.c
+++ b/net/devlink/netlink_gen.c
@@ -32,6 +32,8 @@ 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_U32_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 e0ea93eded43..2d0ef13b562f 100644
--- a/net/devlink/param.c
+++ b/net/devlink/param.c
@@ -252,6 +252,11 @@ devlink_nl_param_value_put(struct sk_buff *msg, enum devlink_param_type type,
 				return -EMSGSIZE;
 		}
 		break;
+	case DEVLINK_PARAM_TYPE_U32_ARRAY:
+		for (int i = 0; i < val.u32arr.size; i++)
+			if (nla_put_u32(msg, nla_type, val.u32arr.val[i]))
+				return -EMSGSIZE;
+		break;
 	}
 	return 0;
 }
@@ -507,7 +512,7 @@ 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 +552,17 @@ 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_U32_ARRAY:
+		cnt = 0;
+		nla_for_each_attr_type(param_data,
+				       DEVLINK_ATTR_PARAM_VALUE_DATA,
+				       genlmsg_data(info->genlhdr),
+				       genlmsg_len(info->genlhdr), rem)
+			value->u32arr.val[cnt++] = nla_get_u32(param_data);
+
+		value->u32arr.size = cnt;
+		break;
 	}
 	return 0;
 }
-- 
2.43.0