From 35c5845957c7982dac1f525ff3412f8acf0a0385 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Tue, 19 Apr 2016 19:49:29 -0400 Subject: net: Add helpers for 64-bit aligning netlink attributes. Suggested-by: Eric Dumazet Suggested-by: Nicolas Dichtel Signed-off-by: David S. Miller --- include/net/netlink.h | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) (limited to 'include/net/netlink.h') diff --git a/include/net/netlink.h b/include/net/netlink.h index 0e3172751755..e644b3489acf 100644 --- a/include/net/netlink.h +++ b/include/net/netlink.h @@ -1230,6 +1230,43 @@ static inline int nla_validate_nested(const struct nlattr *start, int maxtype, return nla_validate(nla_data(start), nla_len(start), maxtype, policy); } +/** + * nla_align_64bit - 64-bit align the nla_data() of next attribute + * @skb: socket buffer the message is stored in + * @padattr: attribute type for the padding + * + * Conditionally emit a padding netlink attribute in order to make + * the next attribute we emit have a 64-bit aligned nla_data() area. + * This will only be done in architectures which do not have + * HAVE_EFFICIENT_UNALIGNED_ACCESS defined. + * + * Returns zero on success or a negative error code. + */ +static inline int nla_align_64bit(struct sk_buff *skb, int padattr) +{ +#ifndef HAVE_EFFICIENT_UNALIGNED_ACCESS + if (IS_ALIGNED((unsigned long)skb->data, 8)) { + struct nlattr *attr = nla_reserve(skb, padattr, 0); + if (!attr) + return -EMSGSIZE; + } +#endif + return 0; +} + +/** + * nla_total_size_64bit - total length of attribute including padding + * @payload: length of payload + */ +static inline int nla_total_size_64bit(int payload) +{ + return NLA_ALIGN(nla_attr_size(payload)) +#ifndef HAVE_EFFICIENT_UNALIGNED_ACCESS + + NLA_ALIGN(nla_attr_size(0)) +#endif + ; +} + /** * nla_for_each_attr - iterate over a stream of attributes * @pos: loop counter, set to current attribute -- cgit v1.2.3-59-g8ed1b