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

[Morten Brørup]

> From: Morten Brørup [mailto:mb at smartsharesystems.com]
> Sent: Tuesday, 5 November 2024 13.28
> 
> > From: Robin Jarry [mailto:rjarry at redhat.com]
> > Sent: Tuesday, 5 November 2024 13.25
> >
> > IPv6 headers are always aligned on a 2-bytes grid. Reflect this in
> the
> > structure definition.
> >
> > Signed-off-by: Robin Jarry <rjarry at redhat.com>
> > ---
> >  lib/net/rte_ip6.h | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > 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
> 
> Reviewed-by: Morten Brørup <mb at smartsharesystems.com>

Too trigger happy, I am.

Please also update the release notes like the IPv4 patch. Suggest:

+++ b/doc/guides/rel_notes/release_24_11.rst
@@ -291,6 +291,8 @@ API Changes
     releases: it handles key=value and only-key cases.
   * Both ``rte_kvargs_process`` and ``rte_kvargs_process_opt`` reject a NULL ``kvlist`` parameter.
 
 * net: The IPv4 header structure ``rte_ipv4_hdr`` has been marked as two bytes aligned.
 
+* net: The IPv6 header and extension structures ``rte_ipv6_hdr``, ``rte_ipv6_routing_ext`` and ``rte_ipv6_fragment_ext`` have been marked as two bytes aligned.
+ 
 * net: The ICMP message types ``RTE_IP_ICMP_ECHO_REPLY`` and ``RTE_IP_ICMP_ECHO_REQUEST``
   are marked as deprecated, and are replaced
   by ``RTE_ICMP_TYPE_ECHO_REPLY`` and ``RTE_ICMP_TYPE_ECHO_REQUEST``.