From a127c18462ea619a1ace1f00540807e009dbf225 Mon Sep 17 00:00:00 2001 From: Joe Damato Date: Fri, 14 Feb 2025 21:12:29 +0000 Subject: [PATCH] netlink: Add nla_put_empty_nest helper Creating empty nests is helpful when the exact attributes to be exposed in the future are not known. Encapsulate the logic in a helper. Signed-off-by: Joe Damato Suggested-by: Jakub Kicinski Link: https://patch.msgid.link/20250214211255.14194-2-jdamato@fastly.com Signed-off-by: Jakub Kicinski --- include/net/netlink.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/include/net/netlink.h b/include/net/netlink.h index e015ffbed819..29e0db940382 100644 --- a/include/net/netlink.h +++ b/include/net/netlink.h @@ -118,6 +118,7 @@ * nla_nest_start(skb, type) start a nested attribute * nla_nest_end(skb, nla) finalize a nested attribute * nla_nest_cancel(skb, nla) cancel nested attribute construction + * nla_put_empty_nest(skb, type) create an empty nest * * Attribute Length Calculations: * nla_attr_size(payload) length of attribute w/o padding @@ -2240,6 +2241,20 @@ static inline void nla_nest_cancel(struct sk_buff *skb, struct nlattr *start) nlmsg_trim(skb, start); } +/** + * nla_put_empty_nest - Create an empty nest + * @skb: socket buffer the message is stored in + * @attrtype: attribute type of the container + * + * This function is a helper for creating empty nests. + * + * Returns: 0 when successful or -EMSGSIZE on failure. + */ +static inline int nla_put_empty_nest(struct sk_buff *skb, int attrtype) +{ + return nla_nest_start(skb, attrtype) ? 0 : -EMSGSIZE; +} + /** * __nla_validate_nested - Validate a stream of nested attributes * @start: container attribute -- 2.50.1