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Miller" , Eric Dumazet , Paolo Abeni , linux-kernel@vger.kernel.org (open list) Subject: [PATCH net-next v6 1/3] netlink: Add nla_put_empty_nest helper Date: Mon, 10 Feb 2025 19:38:39 +0000 Message-ID: <20250210193903.16235-2-jdamato@fastly.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250210193903.16235-1-jdamato@fastly.com> References: <20250210193903.16235-1-jdamato@fastly.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org 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 --- v4: - new in v4 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