[RFC 3/4] net/ixgbe: remove use of VLAs

[Konstantin Ananyev <konstantin.v.ananyev@yandex.ru>]

From: Konstantin Ananyev <konstantin.ananyev@huawei.com>

1) ../drivers/net/ixgbe/ixgbe_ethdev.c:3556:46: warning: variable length array used [-Wvla]
2) ../drivers/net/ixgbe/ixgbe_ethdev.c:3739:23: warning: variable length array used [-Wvla]
3) ../drivers/net/ixgbe/ixgbe_rxtx_vec_common.h:17:24: warning: variable length array used [-Wvla]

For first two cases: in fact ixgbe_xstats_calc_num() always returns
constant value, so it should be safe to replace that function invocation
just with a macro that performs same calculations.
For case #3: reassemble_packets() is invoked only by
ixgbe_recv_scattered_burst_vec().
And in turn, ixgbe_recv_scattered_burst_vec() operates only on fixed
max amount of packets per call: RTE_IXGBE_MAX_RX_BURST.
So, it should be safe to replace VLA with fixed size array.

Signed-off-by: Konstantin Ananyev <konstantin.ananyev@huawei.com>
---
 drivers/net/ixgbe/ixgbe_ethdev.c          | 21 +++++++++++++--------
 drivers/net/ixgbe/ixgbe_rxtx_vec_common.h |  4 +++-
 2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ixgbe/ixgbe_ethdev.c b/drivers/net/ixgbe/ixgbe_ethdev.c
index bbdc996f31..7843cd41d3 100644
--- a/drivers/net/ixgbe/ixgbe_ethdev.c
+++ b/drivers/net/ixgbe/ixgbe_ethdev.c
@@ -3432,11 +3432,16 @@ ixgbe_dev_stats_reset(struct rte_eth_dev *dev)
 }
 
 /* This function calculates the number of xstats based on the current config */
+
+#define IXGBE_XSTATS_CALC_NUM	\
+	(IXGBE_NB_HW_STATS + IXGBE_NB_MACSEC_STATS + \
+	(IXGBE_NB_RXQ_PRIO_STATS * IXGBE_NB_RXQ_PRIO_VALUES) + \
+	(IXGBE_NB_TXQ_PRIO_STATS * IXGBE_NB_TXQ_PRIO_VALUES))
+
 static unsigned
-ixgbe_xstats_calc_num(void) {
-	return IXGBE_NB_HW_STATS + IXGBE_NB_MACSEC_STATS +
-		(IXGBE_NB_RXQ_PRIO_STATS * IXGBE_NB_RXQ_PRIO_VALUES) +
-		(IXGBE_NB_TXQ_PRIO_STATS * IXGBE_NB_TXQ_PRIO_VALUES);
+ixgbe_xstats_calc_num(void)
+{
+	return IXGBE_XSTATS_CALC_NUM;
 }
 
 static int ixgbe_dev_xstats_get_names(__rte_unused struct rte_eth_dev *dev,
@@ -3552,8 +3557,8 @@ static int ixgbe_dev_xstats_get_names_by_id(
 	}
 
 	uint16_t i;
-	uint16_t size = ixgbe_xstats_calc_num();
-	struct rte_eth_xstat_name xstats_names_copy[size];
+	struct rte_eth_xstat_name xstats_names_copy[IXGBE_XSTATS_CALC_NUM];
+	const uint16_t size = RTE_DIM(xstats_names_copy);
 
 	ixgbe_dev_xstats_get_names_by_id(dev, NULL, xstats_names_copy,
 			size);
@@ -3735,8 +3740,8 @@ ixgbe_dev_xstats_get_by_id(struct rte_eth_dev *dev, const uint64_t *ids,
 	}
 
 	uint16_t i;
-	uint16_t size = ixgbe_xstats_calc_num();
-	uint64_t values_copy[size];
+	uint64_t values_copy[IXGBE_XSTATS_CALC_NUM];
+	const uint16_t size = RTE_DIM(values_copy);
 
 	ixgbe_dev_xstats_get_by_id(dev, NULL, values_copy, size);
 
diff --git a/drivers/net/ixgbe/ixgbe_rxtx_vec_common.h b/drivers/net/ixgbe/ixgbe_rxtx_vec_common.h
index a4d9ec9b08..c1cf0a581a 100644
--- a/drivers/net/ixgbe/ixgbe_rxtx_vec_common.h
+++ b/drivers/net/ixgbe/ixgbe_rxtx_vec_common.h
@@ -14,11 +14,13 @@ static inline uint16_t
 reassemble_packets(struct ixgbe_rx_queue *rxq, struct rte_mbuf **rx_bufs,
 		   uint16_t nb_bufs, uint8_t *split_flags)
 {
-	struct rte_mbuf *pkts[nb_bufs]; /*finished pkts*/
+	struct rte_mbuf *pkts[RTE_IXGBE_MAX_RX_BURST]; /*finished pkts*/
 	struct rte_mbuf *start = rxq->pkt_first_seg;
 	struct rte_mbuf *end =  rxq->pkt_last_seg;
 	unsigned int pkt_idx, buf_idx;
 
+	RTE_ASSERT(nb_bufs <= RTE_DIM(pkts));
+
 	for (buf_idx = 0, pkt_idx = 0; buf_idx < nb_bufs; buf_idx++) {
 		if (end != NULL) {
 			/* processing a split packet */
-- 
2.35.3