[PATCH net-next 1/3] net/mlx4: Track RX allocation failures in a stat

[Joe Damato]

mlx4_en_alloc_frags currently returns -ENOMEM when mlx4_alloc_page
fails but does not increment a stat field when this occurs.

struct mlx4_en_rx_ring has a dropped field which is tabulated in
mlx4_en_DUMP_ETH_STATS, but never incremented by the driver.

This change modifies mlx4_en_alloc_frags to increment mlx4_en_rx_ring's
dropped field for the -ENOMEM case.

Signed-off-by: Joe Damato <jdamato@xxxxxxxxxx>
Tested-by: Martin Karsten <mkarsten@xxxxxxxxxxxx>
---
 drivers/net/ethernet/mellanox/mlx4/en_port.c | 4 +++-
 drivers/net/ethernet/mellanox/mlx4/en_rx.c   | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_port.c b/drivers/net/ethernet/mellanox/mlx4/en_port.c
index 532997eba698..c4b1062158e1 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_port.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_port.c
@@ -151,7 +151,7 @@ void mlx4_en_fold_software_stats(struct net_device *dev)
 {
 	struct mlx4_en_priv *priv = netdev_priv(dev);
 	struct mlx4_en_dev *mdev = priv->mdev;
-	unsigned long packets, bytes;
+	unsigned long packets, bytes, dropped;
 	int i;
 
 	if (!priv->port_up || mlx4_is_master(mdev->dev))
@@ -164,9 +164,11 @@ void mlx4_en_fold_software_stats(struct net_device *dev)
 
 		packets += READ_ONCE(ring->packets);
 		bytes   += READ_ONCE(ring->bytes);
+		dropped += READ_ONCE(ring->dropped);
 	}
 	dev->stats.rx_packets = packets;
 	dev->stats.rx_bytes = bytes;
+	dev->stats.rx_missed_errors = dropped;
 
 	packets = 0;
 	bytes = 0;
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
index 8328df8645d5..573ae10300c7 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -82,8 +82,10 @@ static int mlx4_en_alloc_frags(struct mlx4_en_priv *priv,
 
 	for (i = 0; i < priv->num_frags; i++, frags++) {
 		if (!frags->page) {
-			if (mlx4_alloc_page(priv, frags, gfp))
+			if (mlx4_alloc_page(priv, frags, gfp)) {
+				ring->dropped++;
 				return -ENOMEM;
+			}
 			ring->rx_alloc_pages++;
 		}
 		rx_desc->data[i].addr = cpu_to_be64(frags->dma +
-- 
2.25.1