[PATCH dpdk v2] net: enforce 2-bytes alignment on IPv6 headers

[Robin Jarry <rjarry@redhat.com>]

IPv6 headers are always aligned on a 2-bytes grid. Reflect this in the
structure definition.

Signed-off-by: Robin Jarry <rjarry@redhat.com>
---

Notes:
    v2: added changelog entry

 doc/guides/rel_notes/release_24_11.rst | 6 ++++++
 lib/net/rte_ip6.h                      | 6 +++---
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/doc/guides/rel_notes/release_24_11.rst b/doc/guides/rel_notes/release_24_11.rst
index 53a5ffebe552..e27c6831e0f3 100644
--- a/doc/guides/rel_notes/release_24_11.rst
+++ b/doc/guides/rel_notes/release_24_11.rst
@@ -295,6 +295,12 @@ API Changes
   are marked as deprecated, and are replaced
   by ``RTE_ICMP_TYPE_ECHO_REPLY`` and ``RTE_ICMP_TYPE_ECHO_REQUEST``.
 
+* net: The IPv6 header and extension structures have been marked as two bytes aligned:
+
+  - ``struct rte_ipv6_hdr``
+  - ``struct rte_ipv6_routing_ext``
+  - ``struct rte_ipv6_fragment_ext``
+
 * net: A new IPv6 address structure was introduced to replace ad-hoc ``uint8_t[16]`` arrays.
   The following libraries and symbols were modified:
 
diff --git a/lib/net/rte_ip6.h b/lib/net/rte_ip6.h
index 3ae38811b27c..fea7d7b0cd73 100644
--- a/lib/net/rte_ip6.h
+++ b/lib/net/rte_ip6.h
@@ -460,7 +460,7 @@ rte_ether_mcast_from_ipv6(struct rte_ether_addr *mac, const struct rte_ipv6_addr
 /**
  * IPv6 Header
  */
-struct rte_ipv6_hdr {
+struct __rte_aligned(2) rte_ipv6_hdr {
 	union {
 		rte_be32_t vtc_flow;        /**< IP version, traffic class & flow label. */
 		__extension__
@@ -507,7 +507,7 @@ static inline int rte_ipv6_check_version(const struct rte_ipv6_hdr *ip)
 /**
  * IPv6 Routing Extension Header
  */
-struct rte_ipv6_routing_ext {
+struct __rte_aligned(2) rte_ipv6_routing_ext {
 	uint8_t next_hdr;			/**< Protocol, next header. */
 	uint8_t hdr_len;			/**< Header length. */
 	uint8_t type;				/**< Extension header type. */
@@ -751,7 +751,7 @@ rte_ipv6_udptcp_cksum_mbuf_verify(const struct rte_mbuf *m,
 #define RTE_IPV6_SET_FRAG_DATA(fo, mf)	\
 	(((fo) & RTE_IPV6_EHDR_FO_MASK) | ((mf) & RTE_IPV6_EHDR_MF_MASK))
 
-struct rte_ipv6_fragment_ext {
+struct __rte_aligned(2) rte_ipv6_fragment_ext {
 	uint8_t next_header;	/**< Next header type */
 	uint8_t reserved;	/**< Reserved */
 	rte_be16_t frag_data;	/**< All fragmentation data */
-- 
2.47.0