net/mlx4: fix buffer leakage on device close

[ upstream commit b014c6b ]

The mlx4 PMD tracks the buffers (mbufs) for the packets being
transmitted in the dedicated array named as "elts". The tx_burst
routine frees the mbufs from this array once it needs to rearm
the hardware descriptor and store the new mbuf, so it looks
like as replacement mbuf pointer in the elts array.

On the device stop mlx4 PMD freed only the part of elts according
tail and head pointers, leaking the rest of buffers, remained in
the elts array.

Fixes: a2ce212 ("net/mlx4: separate Tx configuration functions")

Signed-off-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>

drivers/net/mlx4/mlx4_rxtx.c

@@ -921,10 +921,6 @@ mlx4_tx_burst(void *dpdk_txq, struct rte_mbuf **pkts, uint16_t pkts_n)
 		if (likely(elt->buf != NULL)) {
 			struct rte_mbuf *tmp = elt->buf;
 
-#ifdef RTE_LIBRTE_MLX4_DEBUG
-			/* Poisoning. */
-			memset(&elt->buf, 0x66, sizeof(struct rte_mbuf *));
-#endif
 			/* Faster than rte_pktmbuf_free(). */
 			do {
 				struct rte_mbuf *next = tmp->next;

drivers/net/mlx4/mlx4_txq.c

@@ -206,19 +206,18 @@ mlx4_tx_uar_uninit_secondary(struct rte_eth_dev *dev __rte_unused)
 static void
 mlx4_txq_free_elts(struct txq *txq)
 {
-	unsigned int elts_head = txq->elts_head;
-	unsigned int elts_tail = txq->elts_tail;
 	struct txq_elt (*elts)[txq->elts_n] = txq->elts;
-	unsigned int elts_m = txq->elts_n - 1;
+	unsigned int n = txq->elts_n;
 
-	DEBUG("%p: freeing WRs", (void *)txq);
-	while (elts_tail != elts_head) {
-		struct txq_elt *elt = &(*elts)[elts_tail++ & elts_m];
+	DEBUG("%p: freeing WRs, %u", (void *)txq, n);
+	while (n--) {
+		struct txq_elt *elt = &(*elts)[n];
 
-		MLX4_ASSERT(elt->buf != NULL);
-		rte_pktmbuf_free(elt->buf);
-		elt->buf = NULL;
-		elt->wqe = NULL;
+		if (elt->buf) {
+			rte_pktmbuf_free(elt->buf);
+			elt->buf = NULL;
+			elt->wqe = NULL;
+		}
 	}
 	txq->elts_tail = txq->elts_head;
 }