devlink: Allow setting of packet trap group parameters

The previous patch allowed device drivers to publish their default
binding between packet trap policers and packet trap groups. However,
some users might not be content with this binding and would like to
change it.

In case user space passed a packet trap policer identifier when setting
a packet trap group, invoke the appropriate device driver callback and
pass the new policer identifier.

v2:
* Check for presence of 'DEVLINK_ATTR_TRAP_POLICER_ID' in
  devlink_trap_group_set() and bail if not present
* Add extack error message in case trap group was partially modified
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/devlink.h

@@ -877,6 +877,15 @@ struct devlink_ops {
 	 */
 	int (*trap_group_init)(struct devlink *devlink,
 			       const struct devlink_trap_group *group);
+	/**
+	 * @trap_group_set: Trap group parameters set function.
+	 *
+	 * Note: @policer can be NULL when a policer is being unbound from
+	 * @group.
+	 */
+	int (*trap_group_set)(struct devlink *devlink,
+			      const struct devlink_trap_group *group,
+			      const struct devlink_trap_policer *policer);
 	/**
 	 * @trap_policer_init: Trap policer initialization function.
 	 *

net/core/devlink.c

@@ -6283,7 +6283,7 @@ __devlink_trap_group_action_set(struct devlink *devlink,
 static int
 devlink_trap_group_action_set(struct devlink *devlink,
 			      struct devlink_trap_group_item *group_item,
-			      struct genl_info *info)
+			      struct genl_info *info, bool *p_modified)
 {
 	enum devlink_trap_action trap_action;
 	int err;
@@ -6302,6 +6302,47 @@ devlink_trap_group_action_set(struct devlink *devlink,
 	if (err)
 		return err;
 
+	*p_modified = true;
+
+	return 0;
+}
+
+static int devlink_trap_group_set(struct devlink *devlink,
+				  struct devlink_trap_group_item *group_item,
+				  struct genl_info *info)
+{
+	struct devlink_trap_policer_item *policer_item;
+	struct netlink_ext_ack *extack = info->extack;
+	const struct devlink_trap_policer *policer;
+	struct nlattr **attrs = info->attrs;
+	int err;
+
+	if (!attrs[DEVLINK_ATTR_TRAP_POLICER_ID])
+		return 0;
+
+	if (!devlink->ops->trap_group_set)
+		return -EOPNOTSUPP;
+
+	policer_item = group_item->policer_item;
+	if (attrs[DEVLINK_ATTR_TRAP_POLICER_ID]) {
+		u32 policer_id;
+
+		policer_id = nla_get_u32(attrs[DEVLINK_ATTR_TRAP_POLICER_ID]);
+		policer_item = devlink_trap_policer_item_lookup(devlink,
+								policer_id);
+		if (policer_id && !policer_item) {
+			NL_SET_ERR_MSG_MOD(extack, "Device did not register this trap policer");
+			return -ENOENT;
+		}
+	}
+	policer = policer_item ? policer_item->policer : NULL;
+
+	err = devlink->ops->trap_group_set(devlink, group_item->group, policer);
+	if (err)
+		return err;
+
+	group_item->policer_item = policer_item;
+
 	return 0;
 }
 
@@ -6311,6 +6352,7 @@ static int devlink_nl_cmd_trap_group_set_doit(struct sk_buff *skb,
 	struct netlink_ext_ack *extack = info->extack;
 	struct devlink *devlink = info->user_ptr[0];
 	struct devlink_trap_group_item *group_item;
+	bool modified = false;
 	int err;
 
 	if (list_empty(&devlink->trap_group_list))
@@ -6322,11 +6364,21 @@ static int devlink_nl_cmd_trap_group_set_doit(struct sk_buff *skb,
 		return -ENOENT;
 	}
 
-	err = devlink_trap_group_action_set(devlink, group_item, info);
+	err = devlink_trap_group_action_set(devlink, group_item, info,
+					    &modified);
 	if (err)
 		return err;
 
+	err = devlink_trap_group_set(devlink, group_item, info);
+	if (err)
+		goto err_trap_group_set;
+
 	return 0;
+
+err_trap_group_set:
+	if (modified)
+		NL_SET_ERR_MSG_MOD(extack, "Trap group set failed, but some changes were committed already");
+	return err;
 }
 
 static struct devlink_trap_policer_item *