net/mlx5e: Add ethtool counter for RX buffer allocation failures

Counts the number of RX buffer allocation failures and shows it
in ethtool statistics.
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx5/core/en.h

@@ -189,6 +189,7 @@ static const char vport_strings[][ETH_GSTRING_LEN] = {
 	"rx_wqe_err",
 	"rx_mpwqe_filler",
 	"rx_mpwqe_frag",
+	"rx_buff_alloc_err",
 };
 
 struct mlx5e_vport_stats {
@@ -232,8 +233,9 @@ struct mlx5e_vport_stats {
 	u64 rx_wqe_err;
 	u64 rx_mpwqe_filler;
 	u64 rx_mpwqe_frag;
+	u64 rx_buff_alloc_err;
 
-#define NUM_VPORT_COUNTERS     37
+#define NUM_VPORT_COUNTERS     38
 };
 
 static const char pport_strings[][ETH_GSTRING_LEN] = {
@@ -329,6 +331,7 @@ static const char rq_stats_strings[][ETH_GSTRING_LEN] = {
 	"wqe_err",
 	"mpwqe_filler",
 	"mpwqe_frag",
+	"buff_alloc_err",
 };
 
 struct mlx5e_rq_stats {
@@ -341,7 +344,8 @@ struct mlx5e_rq_stats {
 	u64 wqe_err;
 	u64 mpwqe_filler;
 	u64 mpwqe_frag;
-#define NUM_RQ_STATS 9
+	u64 buff_alloc_err;
+#define NUM_RQ_STATS 10
 };
 
 static const char sq_stats_strings[][ETH_GSTRING_LEN] = {

drivers/net/ethernet/mellanox/mlx5/core/en_main.c

@@ -180,6 +180,7 @@ void mlx5e_update_stats(struct mlx5e_priv *priv)
 	s->rx_wqe_err		= 0;
 	s->rx_mpwqe_filler	= 0;
 	s->rx_mpwqe_frag	= 0;
+	s->rx_buff_alloc_err	= 0;
 	for (i = 0; i < priv->params.num_channels; i++) {
 		rq_stats = &priv->channel[i]->rq.stats;
 
@@ -192,6 +193,7 @@ void mlx5e_update_stats(struct mlx5e_priv *priv)
 		s->rx_wqe_err   += rq_stats->wqe_err;
 		s->rx_mpwqe_filler += rq_stats->mpwqe_filler;
 		s->rx_mpwqe_frag   += rq_stats->mpwqe_frag;
+		s->rx_buff_alloc_err += rq_stats->buff_alloc_err;
 
 		for (j = 0; j < priv->params.num_tc; j++) {
 			sq_stats = &priv->channel[i]->sq[j].stats;

drivers/net/ethernet/mellanox/mlx5/core/en_rx.c

@@ -447,9 +447,14 @@ bool mlx5e_post_rx_wqes(struct mlx5e_rq *rq)
 
 	while (!mlx5_wq_ll_is_full(wq)) {
 		struct mlx5e_rx_wqe *wqe = mlx5_wq_ll_get_wqe(wq, wq->head);
+		int err;
 
-		if (unlikely(rq->alloc_wqe(rq, wqe, wq->head)))
+		err = rq->alloc_wqe(rq, wqe, wq->head);
+		if (unlikely(err)) {
+			if (err != -EBUSY)
+				rq->stats.buff_alloc_err++;
 			break;
+		}
 
 		mlx5_wq_ll_push(wq, be16_to_cpu(wqe->next.next_wqe_index));
 	}
@@ -701,8 +706,10 @@ void mlx5e_handle_rx_cqe_mpwrq(struct mlx5e_rq *rq, struct mlx5_cqe64 *cqe)
 	skb = napi_alloc_skb(rq->cq.napi,
 			     ALIGN(MLX5_MPWRQ_SMALL_PACKET_THRESHOLD,
 				   sizeof(long)));
-	if (unlikely(!skb))
+	if (unlikely(!skb)) {
+		rq->stats.buff_alloc_err++;
 		goto mpwrq_cqe_out;
+	}
 
 	prefetch(skb->data);
 	cqe_bcnt = mpwrq_get_cqe_byte_cnt(cqe);