[PATCH v1 3/3] net/cnxk: add debug check for number of Tx descriptors

[Ashwin Sekhar T K <asekhar@marvell.com>]

When SG2 descriptors are used and more than 5 segments
are present, in certain combination of segments the
number of descriptors required will be greater than
16.

In debug builds, add an assert to capture this scenario.

Signed-off-by: Ashwin Sekhar T K <asekhar@marvell.com>
---
 drivers/net/cnxk/cn10k_tx.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/net/cnxk/cn10k_tx.h b/drivers/net/cnxk/cn10k_tx.h
index 3f08a8a473..09c332b2b5 100644
--- a/drivers/net/cnxk/cn10k_tx.h
+++ b/drivers/net/cnxk/cn10k_tx.h
@@ -84,6 +84,22 @@ cn10k_nix_mbuf_sg_dwords(struct rte_mbuf *m)
 	return (segw + 1) / 2;
 }
 
+static __plt_always_inline void
+cn10k_nix_tx_mbuf_validate(struct rte_mbuf *m, const uint32_t flags)
+{
+#ifdef RTE_LIBRTE_MBUF_DEBUG
+	uint16_t segdw;
+
+	segdw = cn10k_nix_mbuf_sg_dwords(m);
+	segdw += 1 + !!(flags & NIX_TX_NEED_EXT_HDR) + !!(flags & NIX_TX_OFFLOAD_TSTAMP_F);
+
+	PLT_ASSERT(segdw <= 8);
+#else
+	RTE_SET_USED(m);
+	RTE_SET_USED(flags);
+#endif
+}
+
 static __plt_always_inline void
 cn10k_nix_vwqe_wait_fc(struct cn10k_eth_txq *txq, int64_t req)
 {
@@ -1307,6 +1323,8 @@ cn10k_nix_xmit_pkts_mseg(void *tx_queue, uint64_t *ws,
 	}
 
 	for (i = 0; i < burst; i++) {
+		cn10k_nix_tx_mbuf_validate(tx_pkts[i], flags);
+
 		/* Perform header writes for TSO, barrier at
 		 * lmt steorl will suffice.
 		 */
@@ -1906,6 +1924,8 @@ cn10k_nix_xmit_pkts_vector(void *tx_queue, uint64_t *ws,
 			for (j = 0; j < NIX_DESCS_PER_LOOP; j++) {
 				struct rte_mbuf *m = tx_pkts[j];
 
+				cn10k_nix_tx_mbuf_validate(m, flags);
+
 				/* Get dwords based on nb_segs. */
 				if (!(flags & NIX_TX_OFFLOAD_MBUF_NOFF_F &&
 				      flags & NIX_TX_MULTI_SEG_F))
-- 
2.25.1