+
+ /* Trim skb to allocated size. User is expected to provide buffer as
+ * large as max(min_dump_alloc, 16KiB (mac_recvmsg_len capped at
+ * netlink_recvmsg())). dump will pack as many smaller messages as
+ * could fit within the allocated skb. skb is typically allocated
+ * with larger space than required (could be as much as near 2x the
+ * requested size with align to next power of 2 approach). Allowing
+ * dump to use the excess space makes it difficult for a user to have a
+ * reasonable static buffer based on the expected largest dump of a
+ * single netdev. The outcome is MSG_TRUNC error.
+ */
+ skb_reserve(skb, skb_tailroom(skb) - alloc_size);