net: Add helpers for 64-bit aligning netlink attributes.
Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Suggested-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/netlink.h b/include/net/netlink.h
index 0e31727..e644b34 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -1231,6 +1231,43 @@
}
/**
+ * 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
* @head: head of attribute stream
