net: ena: add statistics for missed tx packets

BugLink: http://bugs.launchpad.net/bugs/1792044

Add a new statistic to ethtool stats that show the number of packets
without transmit acknowledgement from ENA device.
Signed-off-by: Netanel Belgazal <netanel@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 11095fdb)
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Acked-by: Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

drivers/net/ethernet/amazon/ena/ena_ethtool.c

@@ -81,6 +81,7 @@ static const struct ena_stats ena_stats_tx_strings[] = {
 	ENA_STAT_TX_ENTRY(doorbells),
 	ENA_STAT_TX_ENTRY(prepare_ctx_err),
 	ENA_STAT_TX_ENTRY(bad_req_id),
+	ENA_STAT_TX_ENTRY(missed_tx),
 };
 
 static const struct ena_stats ena_stats_rx_strings[] = {

drivers/net/ethernet/amazon/ena/ena_netdev.c

@@ -2636,7 +2636,7 @@ static int check_missing_comp_in_queue(struct ena_adapter *adapter,
 	struct ena_tx_buffer *tx_buf;
 	unsigned long last_jiffies;
 	u32 missed_tx = 0;
-	int i;
+	int i, rc = 0;
 
 	for (i = 0; i < tx_ring->ring_size; i++) {
 		tx_buf = &tx_ring->tx_buffer_info[i];
@@ -2650,21 +2650,25 @@ static int check_missing_comp_in_queue(struct ena_adapter *adapter,
 
 			tx_buf->print_once = 1;
 			missed_tx++;
-
-			if (unlikely(missed_tx > adapter->missing_tx_completion_threshold)) {
-				netif_err(adapter, tx_err, adapter->netdev,
-					  "The number of lost tx completions is above the threshold (%d > %d). Reset the device\n",
-					  missed_tx,
-					  adapter->missing_tx_completion_threshold);
-				adapter->reset_reason =
-					ENA_REGS_RESET_MISS_TX_CMPL;
-				set_bit(ENA_FLAG_TRIGGER_RESET, &adapter->flags);
-				return -EIO;
-			}
 		}
 	}
 
-	return 0;
+	if (unlikely(missed_tx > adapter->missing_tx_completion_threshold)) {
+		netif_err(adapter, tx_err, adapter->netdev,
+			  "The number of lost tx completions is above the threshold (%d > %d). Reset the device\n",
+			  missed_tx,
+			  adapter->missing_tx_completion_threshold);
+		adapter->reset_reason =
+			ENA_REGS_RESET_MISS_TX_CMPL;
+		set_bit(ENA_FLAG_TRIGGER_RESET, &adapter->flags);
+		rc = -EIO;
+	}
+
+	u64_stats_update_begin(&tx_ring->syncp);
+	tx_ring->tx_stats.missed_tx = missed_tx;
+	u64_stats_update_end(&tx_ring->syncp);
+
+	return rc;
 }
 
 static void check_for_missing_tx_completions(struct ena_adapter *adapter)

drivers/net/ethernet/amazon/ena/ena_netdev.h

@@ -182,6 +182,7 @@ struct ena_stats_tx {
 	u64 tx_poll;
 	u64 doorbells;
 	u64 bad_req_id;
+	u64 missed_tx;
 };
 
 struct ena_stats_rx {