[dpdk-dev] [PATCH 4/4] net/fm10k: add compile-time checks to vector driver

[Bruce Richardson <bruce.richardson@intel.com>]

The vector PMD is very sensitive to the layout of the mbuf, especially on
the RX path. Add in some compile-time checks to make sure the mbuf layout
assumptions are valid, and to provide hints to anyone changing the mbuf
where things may need to be updated.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 drivers/net/fm10k/fm10k_rxtx_vec.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/net/fm10k/fm10k_rxtx_vec.c b/drivers/net/fm10k/fm10k_rxtx_vec.c
index 89cd958..c0a8e34 100644
--- a/drivers/net/fm10k/fm10k_rxtx_vec.c
+++ b/drivers/net/fm10k/fm10k_rxtx_vec.c
@@ -331,6 +331,8 @@ fm10k_rxq_rearm(struct fm10k_rx_queue *rxq)
 		*(uint64_t *)p1 = rxq->mbuf_initializer;
 
 		/* load buf_addr(lo 64bit) and buf_physaddr(hi 64bit) */
+		RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, buf_physaddr) !=
+				offsetof(struct rte_mbuf, buf_addr) + 8);
 		vaddr0 = _mm_loadu_si128((__m128i *)&mb0->buf_addr);
 		vaddr1 = _mm_loadu_si128((__m128i *)&mb1->buf_addr);
 
@@ -448,6 +450,19 @@ fm10k_recv_raw_pkts_vec(void *rx_queue, struct rte_mbuf **rx_pkts,
 		0xFF, 0xFF,  /* skip high 16 bits pkt_type */
 		0xFF, 0xFF   /* Skip pkt_type field in shuffle operation */
 		);
+	/*
+	 * Compile-time verify the shuffle mask
+	 * NOTE: some field positions already verified above, but duplicated
+	 * here for completeness in case of future modifications.
+	 */
+	RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, pkt_len) !=
+			offsetof(struct rte_mbuf, rx_descriptor_fields1) + 4);
+	RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, data_len) !=
+			offsetof(struct rte_mbuf, rx_descriptor_fields1) + 8);
+	RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, vlan_tci) !=
+			offsetof(struct rte_mbuf, rx_descriptor_fields1) + 10);
+	RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, hash) !=
+			offsetof(struct rte_mbuf, rx_descriptor_fields1) + 12);
 
 	/* Cache is empty -> need to scan the buffer rings, but first move
 	 * the next 'n' mbufs into the cache
-- 
2.9.3