[dpdk-dev] [PATCH v3 1/1] ip_frag: fix creating ipv6 fragment extension header

[Piotr Azarewicz]

Previous implementation won't work on every environment. The order of
allocation of bit-fields within a unit (high-order to low-order or
low-order to high-order) is implementation-defined.
Solution: used bytes instead of bit fields.

v2 changes:
- remove useless union
- fix process_ipv6 function (due to remove the union above)

v3 changes:
- add macros to read/set fragment_offset and more_flags values

Signed-off-by: Piotr Azarewicz <piotrx.t.azarewicz at intel.com>
---
 lib/librte_ip_frag/rte_ip_frag.h            |   27 ++++++++++++++++-----------
 lib/librte_ip_frag/rte_ipv6_fragmentation.c |   12 ++----------
 lib/librte_port/rte_port_ras.c              |    7 ++++---
 3 files changed, 22 insertions(+), 24 deletions(-)

diff --git a/lib/librte_ip_frag/rte_ip_frag.h b/lib/librte_ip_frag/rte_ip_frag.h
index 52f44c9..92cedf2 100644
--- a/lib/librte_ip_frag/rte_ip_frag.h
+++ b/lib/librte_ip_frag/rte_ip_frag.h
@@ -128,19 +128,24 @@ struct rte_ip_frag_tbl {
 };
 
 /** IPv6 fragment extension header */
+#define	RTE_IPV6_EHDR_MF_SHIFT			0
+#define	RTE_IPV6_EHDR_MF_MASK			1
+#define	RTE_IPV6_EHDR_FO_SHIFT			3
+#define	RTE_IPV6_EHDR_FO_MASK			(~((1 << RTE_IPV6_EHDR_FO_SHIFT) - 1))
+
+#define RTE_IPV6_FRAG_USED_MASK			\
+	(RTE_IPV6_EHDR_MF_MASK | RTE_IPV6_EHDR_FO_MASK)
+
+#define RTE_IPV6_GET_MF(x)				((x) & RTE_IPV6_EHDR_MF_MASK)
+#define RTE_IPV6_GET_FO(x)				((x) >> RTE_IPV6_EHDR_FO_SHIFT)
+
+#define RTE_IPV6_SET_FRAG_DATA(fo, mf)	\
+	(((fo) & RTE_IPV6_EHDR_FO_MASK) | ((mf) & RTE_IPV6_EHDR_MF_MASK))
+
 struct ipv6_extension_fragment {
 	uint8_t next_header;            /**< Next header type */
-	uint8_t reserved1;              /**< Reserved */
-	union {
-		struct {
-			uint16_t frag_offset:13; /**< Offset from the start of the packet */
-			uint16_t reserved2:2; /**< Reserved */
-			uint16_t more_frags:1;
-			/**< 1 if more fragments left, 0 if last fragment */
-		};
-		uint16_t frag_data;
-		/**< union of all fragmentation data */
-	};
+	uint8_t reserved;               /**< Reserved */
+	uint16_t frag_data;             /**< All fragmentation data */
 	uint32_t id;                    /**< Packet ID */
 } __attribute__((__packed__));
 
diff --git a/lib/librte_ip_frag/rte_ipv6_fragmentation.c b/lib/librte_ip_frag/rte_ipv6_fragmentation.c
index 0e32aa8..251a4b8 100644
--- a/lib/librte_ip_frag/rte_ipv6_fragmentation.c
+++ b/lib/librte_ip_frag/rte_ipv6_fragmentation.c
@@ -46,12 +46,6 @@
  *
  */
 
-/* Fragment Extension Header */
-#define	IPV6_HDR_MF_SHIFT			0
-#define	IPV6_HDR_FO_SHIFT			3
-#define	IPV6_HDR_MF_MASK			(1 << IPV6_HDR_MF_SHIFT)
-#define	IPV6_HDR_FO_MASK			((1 << IPV6_HDR_FO_SHIFT) - 1)
-
 static inline void
 __fill_ipv6hdr_frag(struct ipv6_hdr *dst,
 		const struct ipv6_hdr *src, uint16_t len, uint16_t fofs,
@@ -65,10 +59,8 @@ __fill_ipv6hdr_frag(struct ipv6_hdr *dst,
 
 	fh = (struct ipv6_extension_fragment *) ++dst;
 	fh->next_header = src->proto;
-	fh->reserved1   = 0;
-	fh->frag_offset = rte_cpu_to_be_16(fofs);
-	fh->reserved2   = 0;
-	fh->more_frags  = rte_cpu_to_be_16(mf);
+	fh->reserved = 0;
+	fh->frag_data = rte_cpu_to_be_16(RTE_IPV6_SET_FRAG_DATA(fofs, mf));
 	fh->id = 0;
 }
 
diff --git a/lib/librte_port/rte_port_ras.c b/lib/librte_port/rte_port_ras.c
index 6bd0f8c..8a2e554 100644
--- a/lib/librte_port/rte_port_ras.c
+++ b/lib/librte_port/rte_port_ras.c
@@ -212,12 +212,13 @@ process_ipv6(struct rte_port_ring_writer_ras *p, struct rte_mbuf *pkt)
 	struct ipv6_hdr *pkt_hdr = rte_pktmbuf_mtod(pkt, struct ipv6_hdr *);
 
 	struct ipv6_extension_fragment *frag_hdr;
+	uint16_t frag_data = 0;
 	frag_hdr = rte_ipv6_frag_get_ipv6_fragment_header(pkt_hdr);
-	uint16_t frag_offset = frag_hdr->frag_offset;
-	uint16_t frag_flag = frag_hdr->more_frags;
+	if (frag_hdr != NULL)
+		frag_data = rte_be_to_cpu_16(frag_hdr->frag_data);
 
 	/* If it is a fragmented packet, then try to reassemble */
-	if ((frag_flag == 0) && (frag_offset == 0))
+	if ((frag_data & RTE_IPV6_FRAG_USED_MASK) == 0)
 		p->tx_buf[p->tx_buf_count++] = pkt;
 	else {
 		struct rte_mbuf *mo;
-- 
1.7.9.5