Commit a127c184 authored by Joe Damato's avatar Joe Damato Committed by Jakub Kicinski
Browse files

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: default avatarJoe Damato <jdamato@fastly.com>
Suggested-by: default avatarJakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20250214211255.14194-2-jdamato@fastly.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent c935af42

include/net/netlink.h

+15 −0
Original line number Diff line number Diff line
@@ -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