From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Date: Wed,  9 Mar 2016 21:58:31 -0500

Allow device-specific validation of link layer headers. Existing
checks drop all packets shorter than hard_header_len. For variable
length protocols, such packets can be valid.

patch 1 adds header_ops.validate and dev_validate_header
patch 2 implements the protocol specific callback for AX25
patch 3 replaces ll_header_truncated with dev_validate_header

Series applied and queued up for -stable, thanks!