Subject: [PATCH net-next V3 02/15] devlink: define enum for attr types of dynamic attributes

From: Saeed Mahameed <[email-masked]>
Date: Fri, 25 Apr 2025 14:47:55 -0700

From: Jiri Pirko <[email-masked]>

Devlink param and health reporter fmsg use attributes with dynamic type
which is determined according to a different type. Currently used values
are NLA_*. The problem is, they are not part of UAPI. They may change
which would cause a break.

To make this future safe, introduce a enum that shadows NLA_* values in
it and is part of UAPI.

Also, this allows to possibly carry types that are unrelated to NLA_*
values.

Signed-off-by: Saeed Mahameed <[email-masked]>
Signed-off-by: Jiri Pirko <[email-masked]>
---
 Documentation/netlink/specs/devlink.yaml | 24 +++++++++++++++++++
 include/uapi/linux/devlink.h             | 17 ++++++++++++++
 net/devlink/health.c                     | 17 ++++++++++++--
 net/devlink/param.c                      | 30 ++++++++++++------------
 4 files changed, 71 insertions(+), 17 deletions(-)

diff --git a/Documentation/netlink/specs/devlink.yaml b/Documentation/netlink/specs/devlink.yaml
index bd9726269b4f..05fee1b7fe19 100644
--- a/Documentation/netlink/specs/devlink.yaml
+++ b/Documentation/netlink/specs/devlink.yaml
@@ -202,6 +202,28 @@ definitions:
         name: exception
       -
         name: control
+  -
+    type: enum
+    name: var-attr-type
+    entries:
+      -
+        name: u8
+        value: 1
+      -
+        name: u16
+      -
+        name: u32
+      -
+        name: u64
+      -
+        name: string
+      -
+        name: flag
+      -
+        name: nul_string
+        value: 10
+      -
+        name: binary
 
 attribute-sets:
   -
@@ -498,6 +520,7 @@ attribute-sets:
       -
         name: param-type
         type: u8
+        enum: var-attr-type
 
       # TODO: fill in the attributes in between
 
@@ -592,6 +615,7 @@ attribute-sets:
       -
         name: fmsg-obj-value-type
         type: u8
+        enum: var-attr-type
 
       # TODO: fill in the attributes in between
 
diff --git a/include/uapi/linux/devlink.h b/include/uapi/linux/devlink.h
index 9401aa343673..e56f0fcadc45 100644
--- a/include/uapi/linux/devlink.h
+++ b/include/uapi/linux/devlink.h
@@ -385,6 +385,23 @@ enum devlink_linecard_state {
 	DEVLINK_LINECARD_STATE_MAX = __DEVLINK_LINECARD_STATE_MAX - 1
 };
 
+/**
+ * enum devlink_var_attr_type - Dynamic attribute type type.
+ */
+enum devlink_var_attr_type {
+	/* Following values relate to the internal NLA_* values */
+	DEVLINK_VAR_ATTR_TYPE_U8 = 1,
+	DEVLINK_VAR_ATTR_TYPE_U16,
+	DEVLINK_VAR_ATTR_TYPE_U32,
+	DEVLINK_VAR_ATTR_TYPE_U64,
+	DEVLINK_VAR_ATTR_TYPE_STRING,
+	DEVLINK_VAR_ATTR_TYPE_FLAG,
+	DEVLINK_VAR_ATTR_TYPE_NUL_STRING = 10,
+	DEVLINK_VAR_ATTR_TYPE_BINARY,
+	__DEVLINK_VAR_ATTR_TYPE_CUSTOM_BASE = 0x80,
+	/* Any possible custom types, unrelated to NLA_* values go below */
+};
+
 enum devlink_attr {
 	/* don't change the order or add anything between, this is ABI! */
 	DEVLINK_ATTR_UNSPEC,
diff --git a/net/devlink/health.c b/net/devlink/health.c
index 57db6799722a..95a7a62d85a2 100644
--- a/net/devlink/health.c
+++ b/net/devlink/health.c
@@ -930,18 +930,31 @@ EXPORT_SYMBOL_GPL(devlink_fmsg_binary_pair_put);
 static int
 devlink_fmsg_item_fill_type(struct devlink_fmsg_item *msg, struct sk_buff *skb)
 {
+	enum devlink_var_attr_type var_attr_type;
+
 	switch (msg->nla_type) {
 	case NLA_FLAG:
+		var_attr_type = DEVLINK_VAR_ATTR_TYPE_FLAG;
+		break;
 	case NLA_U8:
+		var_attr_type = DEVLINK_VAR_ATTR_TYPE_U8;
+		break;
 	case NLA_U32:
+		var_attr_type = DEVLINK_VAR_ATTR_TYPE_U32;
+		break;
 	case NLA_U64:
+		var_attr_type = DEVLINK_VAR_ATTR_TYPE_U64;
+		break;
 	case NLA_NUL_STRING:
+		var_attr_type = DEVLINK_VAR_ATTR_TYPE_NUL_STRING;
+		break;
 	case NLA_BINARY:
-		return nla_put_u8(skb, DEVLINK_ATTR_FMSG_OBJ_VALUE_TYPE,
-				  msg->nla_type);
+		var_attr_type = DEVLINK_VAR_ATTR_TYPE_BINARY;
+		break;
 	default:
 		return -EINVAL;
 	}
+	return nla_put_u8(skb, DEVLINK_ATTR_FMSG_OBJ_VALUE_TYPE, var_attr_type);
 }
 
 static int
diff --git a/net/devlink/param.c b/net/devlink/param.c
index dcf0d1ccebba..d0fb7c88bdb8 100644
--- a/net/devlink/param.c
+++ b/net/devlink/param.c
@@ -167,19 +167,19 @@ static int devlink_param_set(struct devlink *devlink,
 }
 
 static int
-devlink_param_type_to_nla_type(enum devlink_param_type param_type)
+devlink_param_type_to_var_attr_type(enum devlink_param_type param_type)
 {
 	switch (param_type) {
 	case DEVLINK_PARAM_TYPE_U8:
-		return NLA_U8;
+		return DEVLINK_VAR_ATTR_TYPE_U8;
 	case DEVLINK_PARAM_TYPE_U16:
-		return NLA_U16;
+		return DEVLINK_VAR_ATTR_TYPE_U16;
 	case DEVLINK_PARAM_TYPE_U32:
-		return NLA_U32;
+		return DEVLINK_VAR_ATTR_TYPE_U32;
 	case DEVLINK_PARAM_TYPE_STRING:
-		return NLA_STRING;
+		return DEVLINK_VAR_ATTR_TYPE_STRING;
 	case DEVLINK_PARAM_TYPE_BOOL:
-		return NLA_FLAG;
+		return DEVLINK_VAR_ATTR_TYPE_FLAG;
 	default:
 		return -EINVAL;
 	}
@@ -247,7 +247,7 @@ static int devlink_nl_param_fill(struct sk_buff *msg, struct devlink *devlink,
 	struct devlink_param_gset_ctx ctx;
 	struct nlattr *param_values_list;
 	struct nlattr *param_attr;
-	int nla_type;
+	int var_attr_type;
 	void *hdr;
 	int err;
 	int i;
@@ -294,10 +294,10 @@ static int devlink_nl_param_fill(struct sk_buff *msg, struct devlink *devlink,
 	if (param->generic && nla_put_flag(msg, DEVLINK_ATTR_PARAM_GENERIC))
 		goto param_nest_cancel;
 
-	nla_type = devlink_param_type_to_nla_type(param->type);
-	if (nla_type < 0)
+	var_attr_type = devlink_param_type_to_var_attr_type(param->type);
+	if (var_attr_type < 0)
 		goto param_nest_cancel;
-	if (nla_put_u8(msg, DEVLINK_ATTR_PARAM_TYPE, nla_type))
+	if (nla_put_u8(msg, DEVLINK_ATTR_PARAM_TYPE, var_attr_type))
 		goto param_nest_cancel;
 
 	param_values_list = nla_nest_start_noflag(msg,
@@ -420,19 +420,19 @@ devlink_param_type_get_from_info(struct genl_info *info,
 		return -EINVAL;
 
 	switch (nla_get_u8(info->attrs[DEVLINK_ATTR_PARAM_TYPE])) {
-	case NLA_U8:
+	case DEVLINK_VAR_ATTR_TYPE_U8:
 		*param_type = DEVLINK_PARAM_TYPE_U8;
 		break;
-	case NLA_U16:
+	case DEVLINK_VAR_ATTR_TYPE_U16:
 		*param_type = DEVLINK_PARAM_TYPE_U16;
 		break;
-	case NLA_U32:
+	case DEVLINK_VAR_ATTR_TYPE_U32:
 		*param_type = DEVLINK_PARAM_TYPE_U32;
 		break;
-	case NLA_STRING:
+	case DEVLINK_VAR_ATTR_TYPE_STRING:
 		*param_type = DEVLINK_PARAM_TYPE_STRING;
 		break;
-	case NLA_FLAG:
+	case DEVLINK_VAR_ATTR_TYPE_FLAG:
 		*param_type = DEVLINK_PARAM_TYPE_BOOL;
 		break;
 	default:
-- 
2.49.0