flow: Rearrange IPv6 addresses to remove potential hole in structure.

On some platforms, the in6_addr structure is made up of 16- or 32-bit
members.  Depending on the members of the "flow" structure, this can
lead to holes in the middle.  Moving the IPv6 addresses to the middle
fixes that on these platforms.

diff --git a/lib/flow.h b/lib/flow.h
index 0abfe5a..ff440a2 100644 (file)
--- a/lib/flow.h
+++ b/lib/flow.h
@@ -54,6 +54,9 @@ BUILD_ASSERT_DECL(FLOW_FRAG_LATER == NX_IP_FRAG_LATER);
 
 struct flow {
     ovs_be64 tun_id;            /* Encapsulating tunnel ID. */
+    struct in6_addr ipv6_src;   /* IPv6 source address. */
+    struct in6_addr ipv6_dst;   /* IPv6 destination address. */
+    struct in6_addr nd_target;  /* IPv6 neighbor discovery (ND) target. */
     uint32_t priority;          /* Packet priority for QoS. */
     uint32_t regs[FLOW_N_REGS]; /* Registers. */
     ovs_be32 nw_src;            /* IPv4 source address. */
@@ -69,9 +72,6 @@ struct flow {
     uint8_t tos_frag;           /* IP ToS in top bits, FLOW_FRAG_* in low. */
     uint8_t arp_sha[6];         /* ARP/ND source hardware address. */
     uint8_t arp_tha[6];         /* ARP/ND target hardware address. */
-    struct in6_addr ipv6_src;   /* IPv6 source address. */
-    struct in6_addr ipv6_dst;   /* IPv6 destination address. */
-    struct in6_addr nd_target;  /* IPv6 neighbor discovery (ND) target. */
     uint32_t reserved;          /* Reserved for 64-bit packing. */
 };
 
@@ -79,8 +79,8 @@ struct flow {
  * flow", followed by FLOW_PAD_SIZE bytes of padding. */
 #define FLOW_SIG_SIZE (104 + FLOW_N_REGS * 4)
 #define FLOW_PAD_SIZE 4
-BUILD_ASSERT_DECL(offsetof(struct flow, nd_target) == FLOW_SIG_SIZE - 16);
-BUILD_ASSERT_DECL(sizeof(((struct flow *)0)->nd_target) == 16);
+BUILD_ASSERT_DECL(offsetof(struct flow, arp_tha) == FLOW_SIG_SIZE - 6);
+BUILD_ASSERT_DECL(sizeof(((struct flow *)0)->arp_tha) == 6);
 BUILD_ASSERT_DECL(sizeof(struct flow) == FLOW_SIG_SIZE + FLOW_PAD_SIZE);
 
 /* Remember to update FLOW_WC_SEQ when changing 'struct flow'. */