[PATCH] net/ark: fix index arithmetic optimization bug

[Ed Czeck <ed.czeck@atomicrules.com>]

fix for compiler optimizer error using int32_t.
(a - b) > 0 can behave differently under optimization
at values near max and min bounds.
This patch replaces int32_t with uint32_t except for
necessary casts.

Fixes: 9ee9e0d3b85e ("net/ark: update to reflect FPGA updates")
Cc: stable@dpdk.org

Signed-off-by: Ed Czeck <ed.czeck@atomicrules.com>
---
 drivers/net/ark/ark_ethdev_tx.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ark/ark_ethdev_tx.c b/drivers/net/ark/ark_ethdev_tx.c
index d02a786ee0..b387dadf80 100644
--- a/drivers/net/ark/ark_ethdev_tx.c
+++ b/drivers/net/ark/ark_ethdev_tx.c
@@ -39,8 +39,8 @@ struct ark_tx_queue {
 	uint32_t queue_mask;
 
 	/* 3 indexes to the paired data rings. */
-	int32_t prod_index;		/* where to put the next one */
-	int32_t free_index;		/* mbuf has been freed */
+	uint32_t prod_index;		/* where to put the next one */
+	uint32_t free_index;		/* mbuf has been freed */
 
 	/* The queue Id is used to identify the HW Q */
 	uint16_t phys_qid;
@@ -49,7 +49,7 @@ struct ark_tx_queue {
 
 	/* next cache line - fields written by device */
 	RTE_MARKER cacheline1 __rte_cache_min_aligned;
-	volatile int32_t cons_index;		/* hw is done, can be freed */
+	volatile uint32_t cons_index;		/* hw is done, can be freed */
 } __rte_cache_aligned;
 
 /* Forward declarations */
@@ -108,7 +108,7 @@ eth_ark_xmit_pkts(void *vtxq, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
 	uint32_t user_meta[5];
 
 	int stat;
-	int32_t prod_index_limit;
+	uint32_t prod_index_limit;
 	uint16_t nb;
 	uint8_t user_len = 0;
 	const uint32_t min_pkt_len = ARK_MIN_TX_PKTLEN;
@@ -124,7 +124,7 @@ eth_ark_xmit_pkts(void *vtxq, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
 	prod_index_limit = queue->queue_size + queue->free_index - 4;
 
 	for (nb = 0;
-	     (nb < nb_pkts) && (prod_index_limit - queue->prod_index) > 0;
+	     (nb < nb_pkts) && (int32_t)(prod_index_limit - queue->prod_index) > 0;
 	     ++nb) {
 		mbuf = tx_pkts[nb];
 
@@ -194,13 +194,13 @@ eth_ark_tx_jumbo(struct ark_tx_queue *queue, struct rte_mbuf *mbuf,
 		 uint32_t *user_meta, uint8_t meta_cnt)
 {
 	struct rte_mbuf *next;
-	int32_t free_queue_space;
+	uint32_t free_queue_space;
 	uint8_t flags = ARK_DDM_SOP;
 
 	free_queue_space = queue->queue_mask -
 		(queue->prod_index - queue->free_index);
 	/* We need up to 4 mbufs for first header and 2 for subsequent ones */
-	if (unlikely(free_queue_space < (2 + (2 * mbuf->nb_segs))))
+	if (unlikely(free_queue_space < (2U + (2U * mbuf->nb_segs))))
 		return -1;
 
 	while (mbuf != NULL) {
@@ -392,10 +392,11 @@ free_completed_tx(struct ark_tx_queue *queue)
 {
 	struct rte_mbuf *mbuf;
 	union ark_tx_meta *meta;
-	int32_t top_index;
+	uint32_t top_index;
 
 	top_index = queue->cons_index;	/* read once */
-	while ((top_index - queue->free_index) > 0) {
+
+	while ((int32_t)(top_index - queue->free_index) > 0) {
 		meta = &queue->meta_q[queue->free_index & queue->queue_mask];
 		if (likely((meta->flags & ARK_DDM_SOP) != 0)) {
 			mbuf = queue->bufs[queue->free_index &
-- 
2.34.1